Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Protected Ctors](https://developer.android.com/reference/java/lang/ClassLoader#proctors) \| [Methods](https://developer.android.com/reference/java/lang/ClassLoader#pubmethods) \| [Protected Methods](https://developer.android.com/reference/java/lang/ClassLoader#promethods) \| [Inherited Methods](https://developer.android.com/reference/java/lang/ClassLoader#inhmethods)
# ClassLoader
`
public
abstract
class
ClassLoader
`
`
extends https://developer.android.com/reference/java/lang/Object
`
`
`
|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | java.lang.ClassLoader |
|---|
| Known direct subclasses [BaseDexClassLoader](https://developer.android.com/reference/dalvik/system/BaseDexClassLoader), [SecureClassLoader](https://developer.android.com/reference/java/security/SecureClassLoader) |---|---| | [BaseDexClassLoader](https://developer.android.com/reference/dalvik/system/BaseDexClassLoader) | Base class for common functionality between various dex-based `https://developer.android.com/reference/java/lang/ClassLoader` implementations. | | [SecureClassLoader](https://developer.android.com/reference/java/security/SecureClassLoader) | This class extends ClassLoader with additional support for defining classes with an associated code source and permissions which are retrieved by the system policy by default. | |
|---|
| Known indirect subclasses [DelegateLastClassLoader](https://developer.android.com/reference/dalvik/system/DelegateLastClassLoader), [DexClassLoader](https://developer.android.com/reference/dalvik/system/DexClassLoader), [InMemoryDexClassLoader](https://developer.android.com/reference/dalvik/system/InMemoryDexClassLoader), [PathClassLoader](https://developer.android.com/reference/dalvik/system/PathClassLoader), [URLClassLoader](https://developer.android.com/reference/java/net/URLClassLoader) |---|---| | [DelegateLastClassLoader](https://developer.android.com/reference/dalvik/system/DelegateLastClassLoader) | A `ClassLoader` implementation that implements a **delegate last** lookup policy. | | [DexClassLoader](https://developer.android.com/reference/dalvik/system/DexClassLoader) | A class loader that loads classes from `.jar` and `.apk` files containing a `classes.dex` entry. | | [InMemoryDexClassLoader](https://developer.android.com/reference/dalvik/system/InMemoryDexClassLoader) | A `https://developer.android.com/reference/java/lang/ClassLoader` implementation that loads classes from a buffer containing a DEX file. | | [PathClassLoader](https://developer.android.com/reference/dalvik/system/PathClassLoader) | Provides a simple `https://developer.android.com/reference/java/lang/ClassLoader` implementation that operates on a list of files and directories in the local file system, but does not attempt to load classes from the network. | | [URLClassLoader](https://developer.android.com/reference/java/net/URLClassLoader) | This class loader is used to load classes and resources from a search path of URLs referring to both JAR files and directories. | |
*** ** * ** ***
A class loader is an object that is responsible for loading classes. The
class `ClassLoader` is an abstract class. Given the [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of a class, a class loader should attempt to
locate or generate data that constitutes a definition for the class. A
typical strategy is to transform the name into a file name and then read a
"class file" of that name from a file system.
Every `https://developer.android.com/reference/java/lang/Class` object contains a `https://developer.android.com/reference/java/lang/Class#getClassLoader()` to the `ClassLoader` that defined
it.
`Class` objects for array classes are not created by class
loaders, but are created automatically as required by the Java runtime.
The class loader for an array class, as returned by `https://developer.android.com/reference/java/lang/Class#getClassLoader()` is the same as the class loader for its element
type; if the element type is a primitive type, then the array class has no
class loader.
Applications implement subclasses of `ClassLoader` in order to
extend the manner in which the Java virtual machine dynamically loads
classes.
Class loaders may typically be used by security managers to indicate
security domains.
In addition to loading classes, a class loader is also responsible for
locating resources. A resource is some data (a "`.class`" file,
configuration data, or an image for example) that is identified with an
abstract '/'-separated path name. Resources are typically packaged with an
application or library so that they can be located by code in the
application or library. In some cases, the resources are included so that
they can be located by other libraries.
The `ClassLoader` class uses a delegation model to search for
classes and resources. Each instance of `ClassLoader` has an
associated parent class loader. When requested to find a class or
resource, a `ClassLoader` instance will usually delegate the search
for the class or resource to its parent class loader before attempting to
find the class or resource itself.
Class loaders that support concurrent loading of classes are known as
*`#isRegisteredAsParallelCapable() parallel capable`* class
loaders and are required to register themselves at their class initialization
time by invoking the `#registerAsParallelCapable ClassLoader.registerAsParallelCapable`
method. Note that the `ClassLoader` class is registered as parallel
capable by default. However, its subclasses still need to register themselves
if they are parallel capable.
In environments in which the delegation model is not strictly
hierarchical, class loaders need to be parallel capable, otherwise class
loading can lead to deadlocks because the loader lock is held for the
duration of the class loading process (see `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String)` methods).
## Run-time Built-in Class Loaders
The Java run-time has the following built-in class loaders:
- Bootstrap class loader.
It is the virtual machine's built-in class loader, typically represented
as `null`, and does not have a parent.
- [System class loader](https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()).
It is also known as *application class loader* and is distinct
from the platform class loader.
The system class loader is typically used to define classes on the
application class path, module path, and JDK-specific tools.
The platform class loader is the parent or an ancestor of the system class
loader, so the system class loader can load platform classes by delegating
to its parent.
Normally, the Java virtual machine loads classes from the local file
system in a platform-dependent manner.
However, some classes may not originate from a file; they may originate
from other sources, such as the network, or they could be constructed by an
application. The method `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)` converts an array of bytes into an instance of class
`Class`. Instances of this newly defined class can be created using
`https://developer.android.com/reference/java/lang/Class#newInstance()`.
The methods and constructors of objects created by a class loader may
reference other classes. To determine the class(es) referred to, the Java
virtual machine invokes the `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String)` method of
the class loader that originally created the class.
For example, an application could create a network class loader to
download class files from a server. Sample code might look like:
> ```
> ClassLoader loader = new NetworkClassLoader(host, port);
> Object main = loader.loadClass("Main", true).newInstance();
> . . .
> ```
The network class loader subclass must define the methods `https://developer.android.com/reference/java/lang/ClassLoader#findClass(java.lang.String)` and `loadClassData` to load a class
from the network. Once it has downloaded the bytes that make up the class,
it should use the method `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(byte[],%20int,%20int)` to
create a class instance. A sample implementation is:
> ```
> class NetworkClassLoader extends ClassLoader {
> String host;
> int port;
>
> public Class findClass(String name) {
> byte[] b = loadClassData(name);
> return defineClass(name, b, 0, b.length);
> }
>
> private byte[] loadClassData(String name) {
> // load the class data from the connection
> . . .
> }
> }
> ```
### Binary names
Any class name provided as a `String` parameter to methods in
`ClassLoader` must be a binary name as defined by
The Java Language Specification.
Examples of valid class names include:
>
> ```
> "java.lang.String"
> "javax.swing.JSpinner$DefaultEditor"
> "java.security.KeyStore$Builder$FileBuilder$1"
> "java.net.URLClassLoader$3$1"
> ```
Any package name provided as a `String` parameter to methods in
`ClassLoader` must be either the empty string (denoting an unnamed package)
or a fully qualified name as defined by
The Java Language Specification.
**See also:**
- `https://developer.android.com/reference/java/lang/ClassLoader#resolveClass(java.lang.Class)`
## Summary
| ### Protected constructors ||
|---|---|
| ` https://developer.android.com/reference/java/lang/ClassLoader#ClassLoader()() ` Creates a new class loader using the `ClassLoader` returned by the method `https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()` as the parent class loader. |
| ` https://developer.android.com/reference/java/lang/ClassLoader#ClassLoader(java.lang.ClassLoader)(https://developer.android.com/reference/java/lang/ClassLoader parent) ` Creates a new class loader using the specified parent class loader for delegation. |
| ### Public methods ||
|---|---|
| ` void` | ` https://developer.android.com/reference/java/lang/ClassLoader#clearAssertionStatus()() ` Sets the default assertion status for this class loader to `false` and discards any package defaults or class assertion status settings associated with the class loader. |
| ` final https://developer.android.com/reference/java/lang/ClassLoader` | ` https://developer.android.com/reference/java/lang/ClassLoader#getParent()() ` Returns the parent class loader for delegation. |
| ` https://developer.android.com/reference/java/net/URL` | ` https://developer.android.com/reference/java/lang/ClassLoader#getResource(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Finds the resource with the given name. |
| ` https://developer.android.com/reference/java/io/InputStream` | ` https://developer.android.com/reference/java/lang/ClassLoader#getResourceAsStream(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Returns an input stream for reading the specified resource. |
| ` https://developer.android.com/reference/java/util/Enumeration` | ` https://developer.android.com/reference/java/lang/ClassLoader#getResources(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Finds all the resources with the given name. |
| ` static https://developer.android.com/reference/java/lang/ClassLoader` | ` https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()() ` Returns the system class loader. |
| ` static https://developer.android.com/reference/java/net/URL` | ` https://developer.android.com/reference/java/lang/ClassLoader#getSystemResource(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Find a resource of the specified name from the search path used to load classes. |
| ` static https://developer.android.com/reference/java/io/InputStream` | ` https://developer.android.com/reference/java/lang/ClassLoader#getSystemResourceAsStream(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Open for reading, a resource of the specified name from the search path used to load classes. |
| ` static https://developer.android.com/reference/java/util/Enumeration` | ` https://developer.android.com/reference/java/lang/ClassLoader#getSystemResources(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Finds all resources of the specified name from the search path used to load classes. |
| ` https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Loads the class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). |
| ` void` | ` https://developer.android.com/reference/java/lang/ClassLoader#setClassAssertionStatus(java.lang.String,%20boolean)(https://developer.android.com/reference/java/lang/String className, boolean enabled) ` Sets the desired assertion status for the named top-level class in this class loader and any nested classes contained therein. |
| ` void` | ` https://developer.android.com/reference/java/lang/ClassLoader#setDefaultAssertionStatus(boolean)(boolean enabled) ` Sets the default assertion status for this class loader. |
| ` void` | ` https://developer.android.com/reference/java/lang/ClassLoader#setPackageAssertionStatus(java.lang.String,%20boolean)(https://developer.android.com/reference/java/lang/String packageName, boolean enabled) ` Sets the package default assertion status for the named package. |
| ### Protected methods ||
|---|---|
| ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)(https://developer.android.com/reference/java/lang/String name, byte[] b, int off, int len, https://developer.android.com/reference/java/security/ProtectionDomain protectionDomain) ` Converts an array of bytes into an instance of class `Class`, with a given `ProtectionDomain`. |
| ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20java.nio.ByteBuffer,%20java.security.ProtectionDomain)(https://developer.android.com/reference/java/lang/String name, https://developer.android.com/reference/java/nio/ByteBuffer b, https://developer.android.com/reference/java/security/ProtectionDomain protectionDomain) ` Converts a `https://developer.android.com/reference/java/nio/ByteBuffer` into an instance of class `Class`, with the given `ProtectionDomain`. |
| ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#defineClass(byte[],%20int,%20int)(byte[] b, int off, int len) ` *This method was deprecated in API level 15. Replaced by `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)`* |
| ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)(https://developer.android.com/reference/java/lang/String name, byte[] b, int off, int len) ` Converts an array of bytes into an instance of class `Class`. |
| ` https://developer.android.com/reference/java/lang/Package` | ` https://developer.android.com/reference/java/lang/ClassLoader#definePackage(java.lang.String,%20java.lang.String,%20java.lang.String,%20java.lang.String,%20java.lang.String,%20java.lang.String,%20java.lang.String,%20java.net.URL)(https://developer.android.com/reference/java/lang/String name, https://developer.android.com/reference/java/lang/String specTitle, https://developer.android.com/reference/java/lang/String specVersion, https://developer.android.com/reference/java/lang/String specVendor, https://developer.android.com/reference/java/lang/String implTitle, https://developer.android.com/reference/java/lang/String implVersion, https://developer.android.com/reference/java/lang/String implVendor, https://developer.android.com/reference/java/net/URL sealBase) ` Defines a package by [name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) in this `ClassLoader`. |
| ` https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#findClass(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Finds the class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). |
| ` https://developer.android.com/reference/java/lang/String` | ` https://developer.android.com/reference/java/lang/ClassLoader#findLibrary(java.lang.String)(https://developer.android.com/reference/java/lang/String libname) ` Returns the absolute path name of a native library. |
| ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#findLoadedClass(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Returns the class with the given [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) if this loader has been recorded by the Java virtual machine as an initiating loader of a class with that [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). |
| ` https://developer.android.com/reference/java/net/URL` | ` https://developer.android.com/reference/java/lang/ClassLoader#findResource(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Finds the resource with the given name. |
| ` https://developer.android.com/reference/java/util/Enumeration` | ` https://developer.android.com/reference/java/lang/ClassLoader#findResources(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Returns an enumeration of `https://developer.android.com/reference/java/net/URL` objects representing all the resources with the given name. |
| ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#findSystemClass(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` Finds a class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name), loading it if necessary. |
| ` https://developer.android.com/reference/java/lang/Package` | ` https://developer.android.com/reference/java/lang/ClassLoader#getPackage(java.lang.String)(https://developer.android.com/reference/java/lang/String name) ` *This method was deprecated in API level 35. If multiple class loaders delegate to each other and define classes with the same package name, and one such loader relies on the lookup behavior of `getPackage` to return a `Package` from a parent loader, then the properties exposed by the `Package` may not be as expected in the rest of the program. For example, the `Package` will only expose annotations from the `package-info.class` file defined by the parent loader, even if annotations exist in a `package-info.class` file defined by a child loader.* |
| ` https://developer.android.com/reference/java/lang/Package` | ` https://developer.android.com/reference/java/lang/ClassLoader#getPackages()() ` Returns all of the `Package`s that have been defined by this class loader and its ancestors. |
| ` https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String,%20boolean)(https://developer.android.com/reference/java/lang/String name, boolean resolve) ` Loads the class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). |
| ` static boolean` | ` https://developer.android.com/reference/java/lang/ClassLoader#registerAsParallelCapable()() ` Registers the caller as `#isRegisteredAsParallelCapable() parallel capable`. |
| ` final void` | ` https://developer.android.com/reference/java/lang/ClassLoader#resolveClass(java.lang.Class)(https://developer.android.com/reference/java/lang/Class c) ` Links the specified class. |
| ` final void` | ` https://developer.android.com/reference/java/lang/ClassLoader#setSigners(java.lang.Class,%20java.lang.Object[])(https://developer.android.com/reference/java/lang/Class c, https://developer.android.com/reference/java/lang/Object signers) ` Sets the signers of a class. |
| ### Inherited methods |
|---|---|
| From class ` https://developer.android.com/reference/java/lang/Object ` |---|---| | ` https://developer.android.com/reference/java/lang/Object` | ` https://developer.android.com/reference/java/lang/Object#clone()() ` Creates and returns a copy of this object. | | ` boolean` | ` https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj) ` Indicates whether some other object is "equal to" this one. | | ` void` | ` https://developer.android.com/reference/java/lang/Object#finalize()() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. | | ` final https://developer.android.com/reference/java/lang/Class` | ` https://developer.android.com/reference/java/lang/Object#getClass()() ` Returns the runtime class of this `Object`. | | ` int` | ` https://developer.android.com/reference/java/lang/Object#hashCode()() ` Returns a hash code value for the object. | | ` final void` | ` https://developer.android.com/reference/java/lang/Object#notify()() ` Wakes up a single thread that is waiting on this object's monitor. | | ` final void` | ` https://developer.android.com/reference/java/lang/Object#notifyAll()() ` Wakes up all threads that are waiting on this object's monitor. | | ` https://developer.android.com/reference/java/lang/String` | ` https://developer.android.com/reference/java/lang/Object#toString()() ` Returns a string representation of the object. | | ` final void` | ` https://developer.android.com/reference/java/lang/Object#wait(long,%20int)(long timeoutMillis, int nanos) ` Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` https://developer.android.com/reference/java/lang/Object#wait(long)(long timeoutMillis) ` Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` https://developer.android.com/reference/java/lang/Object#wait()() ` Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*. | ||
## Protected constructors
### ClassLoader
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected ClassLoader ()
```
Creates a new class loader using the `ClassLoader` returned by
the method `https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()` as the parent class loader.
If there is a security manager, its `https://developer.android.com/reference/java/lang/SecurityManager#checkCreateClassLoader()` method is invoked. This may result in
a security exception.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/SecurityException` | If a security manager exists and its `checkCreateClassLoader` method doesn't allow creation of a new class loader. |
### ClassLoader
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected ClassLoader (ClassLoader parent)
```
Creates a new class loader using the specified parent class loader for
delegation.
If there is a security manager, its `https://developer.android.com/reference/java/lang/SecurityManager#checkCreateClassLoader()` method
is invoked. This may result in a security exception.
##### API Note:
- If the parent is specified as `null` (for the bootstrap class loader) then there is no guarantee that all platform classes are visible.
| Parameters ||
|---|---|
| `parent` | `ClassLoader`: The parent class loader
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/SecurityException` | If a security manager exists and its `checkCreateClassLoader` method doesn't allow creation of a new class loader. |
## Public methods
### clearAssertionStatus
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void clearAssertionStatus ()
```
Sets the default assertion status for this class loader to
`false` and discards any package defaults or class assertion
status settings associated with the class loader. This method is
provided so that class loaders can be made to ignore any command line or
persistent assertion status settings and "start with a clean slate."
Android-note: AssertionStatuses are unsupported. This method is a no-op.
### getParent
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final ClassLoader getParent ()
```
Returns the parent class loader for delegation. Some implementations may
use `null` to represent the bootstrap class loader. This method
will return `null` in such implementations if this class loader's
parent is the bootstrap class loader.
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassLoader` | The parent `ClassLoader`
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/SecurityException` | If a security manager is present, and the caller's class loader is not `null` and is not an ancestor of this class loader, and the caller does not have the `https://developer.android.com/reference/java/lang/RuntimePermission``("getClassLoader")` |
### getResource
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public URL getResource (String name)
```
Finds the resource with the given name. A resource is some data
(images, audio, text, etc) that can be accessed by class code in a way
that is independent of the location of the code.
The name of a resource is a '`/`'-separated path name thatf
identifies the resource.
##### API Note:
- Where several modules are defined to the same class loader, and where more than one module contains a resource with the given name, then the ordering that modules are searched is not specified and may be very unpredictable. When overriding this method it is recommended that an implementation ensures that any delegation is consistent with the `https://developer.android.com/reference/java/lang/ClassLoader#getResources(java.lang.String)` method.
##### Implementation Requirements:
- The default implementation will first search the parent class loader for the resource; if the parent is `null` the path of the class loader built into the virtual machine is searched. If not found, this method will invoke `https://developer.android.com/reference/java/lang/ClassLoader#findResource(java.lang.String)` to find the resource.
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/net/URL` | `URL` object for reading the resource; `null` if the resource could not be found, a `URL` could not be constructed to locate the resource, the resource is in a package that is not opened unconditionally, or access to the resource is denied by the security manager.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | If `name` is `null` |
### getResourceAsStream
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public InputStream getResourceAsStream (String name)
```
Returns an input stream for reading the specified resource.
The search order is described in the documentation for `https://developer.android.com/reference/java/lang/ClassLoader#getResource(java.lang.String)`.
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/io/InputStream` | An input stream for reading the resource; `null` if the resource could not be found, the resource is in a package that is not opened unconditionally, or access to the resource is denied by the security manager.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | If `name` is `null` |
### getResources
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Enumeration getResources (String name)
```
Finds all the resources with the given name. A resource is some data
(images, audio, text, etc) that can be accessed by class code in a way
that is independent of the location of the code.
The name of a resource is a `/`-separated path name that
identifies the resource.
##### API Note:
- Where several modules are defined to the same class loader, and where more than one module contains a resource with the given name, then the ordering is not specified and may be very unpredictable. When overriding this method it is recommended that an implementation ensures that any delegation is consistent with the `https://developer.android.com/reference/java/lang/ClassLoader#getResource(java.lang.String)` method. This should ensure that the first element returned by the Enumeration's `nextElement` method is the same resource that the `getResource(String)` method would return.
##### Implementation Requirements:
- The default implementation will first search the parent class loader for the resource; if the parent is `null` the path of the class loader built into the virtual machine is searched. It then invokes `https://developer.android.com/reference/java/lang/ClassLoader#findResources(java.lang.String)` to find the resources with the name in this class loader. It returns an enumeration whose elements are the URLs found by searching the parent class loader followed by the elements found with `findResources`.
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Enumeration` | An enumeration of `https://developer.android.com/reference/java/net/URL` objects for the resource. If no resources could be found, the enumeration will be empty. Resources for which a `URL` cannot be constructed, are in a package that is not opened unconditionally, or access to the resource is denied by the security manager, are not returned in the enumeration.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | If I/O errors occur |
| `https://developer.android.com/reference/java/lang/NullPointerException` | If `name` is `null` |
### getSystemClassLoader
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static ClassLoader getSystemClassLoader ()
```
Returns the system class loader. This is the default
delegation parent for new `ClassLoader` instances, and is
typically the class loader used to start the application.
This method is first invoked early in the runtime's startup
sequence, at which point it creates the system class loader. This
class loader will be the context class loader for the main application
thread (for example, the thread that invokes the `main` method of
the main class).
The default system class loader is an implementation-dependent
instance of this class.
##### Implementation Note:
- The system property to override the system class loader is not examined until the VM is almost fully initialized. Code that executes this method during startup should take care not to cache the return value until the system is fully initialized. The name of the built-in system class loader is `"app"`.
The system property "`java.class.path`" is read during early
initialization of the VM to determine the class path.
An empty value of "`java.class.path`" property is interpreted
differently depending on whether the initial module (the module
containing the main class) is named or unnamed:
If named, the built-in system class loader will have no class path and
will search for classes and resources using the application module path;
otherwise, if unnamed, it will set the class path to the current
working directory.
JAR files on the class path may contain a `Class-Path` manifest
attribute to specify dependent JAR files to be included in the class path.
`Class-Path` entries must meet certain conditions for validity (see
the [JAR File Specification](https://docs.oracle.com/en/java/javase/17/docs/specs/jar/jar.html#class-path-attribute) for details). Invalid `Class-Path`
entries are ignored.
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassLoader` | The system `ClassLoader`
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/Error` | If the system property "`java.system.class.loader`" is defined but the named class could not be loaded, the provider class does not define the required constructor, or an exception is thrown by that constructor when it is invoked. The underlying cause of the error can be retrieved via the `https://developer.android.com/reference/java/lang/Throwable#getCause()` method. |
| `https://developer.android.com/reference/java/lang/IllegalStateException` | If invoked recursively during the construction of the class loader specified by the "`java.system.class.loader`" property. |
| `https://developer.android.com/reference/java/lang/SecurityException` | If a security manager is present, and the caller's class loader is not `null` and is not the same as or an ancestor of the system class loader, and the caller does not have the `https://developer.android.com/reference/java/lang/RuntimePermission``("getClassLoader")` |
### getSystemResource
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static URL getSystemResource (String name)
```
Find a resource of the specified name from the search path used to load
classes. This method locates the resource through the system class
loader (see `https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()`).
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/net/URL` | A `https://developer.android.com/reference/java/net/URL` to the resource; `null` if the resource could not be found, a URL could not be constructed to locate the resource, the resource is in a package that is not opened unconditionally or access to the resource is denied by the security manager.
|
### getSystemResourceAsStream
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static InputStream getSystemResourceAsStream (String name)
```
Open for reading, a resource of the specified name from the search path
used to load classes. This method locates the resource through the
system class loader (see `https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()`).
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/io/InputStream` | An input stream for reading the resource; `null` if the resource could not be found, the resource is in a package that is not opened unconditionally, or access to the resource is denied by the security manager.
|
### getSystemResources
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static Enumeration getSystemResources (String name)
```
Finds all resources of the specified name from the search path used to
load classes. The resources thus found are returned as an
`https://developer.android.com/reference/java/util/Enumeration` of `https://developer.android.com/reference/java/net/URL` objects.
The search order is described in the documentation for `https://developer.android.com/reference/java/lang/ClassLoader#getSystemResource(java.lang.String)`.
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Enumeration` | An enumeration of `https://developer.android.com/reference/java/net/URL` objects for the resource. If no resources could be found, the enumeration will be empty. Resources for which a `URL` cannot be constructed, are in a package that is not opened unconditionally, or access to the resource is denied by the security manager, are not returned in the enumeration.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | If I/O errors occur |
### loadClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Class loadClass (String name)
```
Loads the class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name).
This method searches for classes in the same manner as the `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String,%20boolean)` method. It is invoked by the Java virtual
machine to resolve class references. Invoking this method is equivalent
to invoking `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String,%20boolean)`.
| Parameters ||
|---|---|
| `name` | `String`: The [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The resulting `Class` object
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassNotFoundException` | If the class was not found |
### setClassAssertionStatus
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setClassAssertionStatus (String className,
boolean enabled)
```
Sets the desired assertion status for the named top-level class in this
class loader and any nested classes contained therein. This setting
takes precedence over the class loader's default assertion status, and
over any applicable per-package default. This method has no effect if
the named class has already been initialized. (Once a class is
initialized, its assertion status cannot change.)
If the named class is not a top-level class, this invocation will
have no effect on the actual assertion status of any class.
Android-note: AssertionStatuses are unsupported. This method is a no-op.
| Parameters ||
|---|---|
| `className` | `String`: The fully qualified class name of the top-level class whose assertion status is to be set.
|
| `enabled` | `boolean`: `true` if the named class is to have assertions enabled when (and if) it is initialized, `false` if the class is to have assertions disabled.
|
### setDefaultAssertionStatus
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setDefaultAssertionStatus (boolean enabled)
```
Sets the default assertion status for this class loader. This setting
determines whether classes loaded by this class loader and initialized
in the future will have assertions enabled or disabled by default.
This setting may be overridden on a per-package or per-class basis by
invoking `https://developer.android.com/reference/java/lang/ClassLoader#setPackageAssertionStatus(java.lang.String,%20boolean)` or `https://developer.android.com/reference/java/lang/ClassLoader#setClassAssertionStatus(java.lang.String,%20boolean)`.
Android-note: AssertionStatuses are unsupported. This method is a no-op.
| Parameters ||
|---|---|
| `enabled` | `boolean`: `true` if classes loaded by this class loader will henceforth have assertions enabled by default, `false` if they will have assertions disabled by default.
|
### setPackageAssertionStatus
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setPackageAssertionStatus (String packageName,
boolean enabled)
```
Sets the package default assertion status for the named package. The
package default assertion status determines the assertion status for
classes initialized in the future that belong to the named package or
any of its "subpackages".
A subpackage of a package named p is any package whose name begins
with "`p.`". For example, `javax.swing.text` is a
subpackage of `javax.swing`, and both `java.util` and
`java.lang.reflect` are subpackages of `java`.
In the event that multiple package defaults apply to a given class,
the package default pertaining to the most specific package takes
precedence over the others. For example, if `javax.lang` and
`javax.lang.reflect` both have package defaults associated with
them, the latter package default applies to classes in
`javax.lang.reflect`.
Package defaults take precedence over the class loader's default
assertion status, and may be overridden on a per-class basis by invoking
`https://developer.android.com/reference/java/lang/ClassLoader#setClassAssertionStatus(java.lang.String,%20boolean)`.
Android-note: AssertionStatuses are unsupported. This method is a no-op.
| Parameters ||
|---|---|
| `packageName` | `String`: The name of the package whose package default assertion status is to be set. A `null` value indicates the unnamed package that is "current" (see section {@jls 7.4.2} of The Java Language Specification.)
|
| `enabled` | `boolean`: `true` if classes loaded by this classloader and belonging to the named package or any of its subpackages will have assertions enabled by default, `false` if they will have assertions disabled by default.
|
## Protected methods
### defineClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final Class defineClass (String name,
byte[] b,
int off,
int len,
ProtectionDomain protectionDomain)
```
Converts an array of bytes into an instance of class `Class`,
with a given `ProtectionDomain`.
If the given `ProtectionDomain` is `null`,
then a default protection domain will be assigned to the class as specified
in the documentation for `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)`.
Before the class can be used it must be resolved.
The first class defined in a package determines the exact set of
certificates that all subsequent classes defined in that package must
contain. The set of certificates for a class is obtained from the
`https://developer.android.com/reference/java/security/CodeSource` within the
`ProtectionDomain` of the class. Any classes added to that
package must contain the same set of certificates or a
`SecurityException` will be thrown. Note that if
`name` is `null`, this check is not performed.
You should always pass in the [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the
class you are defining as well as the bytes. This ensures that the
class you are defining is indeed the class you think it is.
This method defines a package in this class loader corresponding to the
package of the `Class` (if such a package has not already been defined
in this class loader). The name of the defined package is derived from
the [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class specified by
the byte array `b`.
Other properties of the defined package are as specified by `https://developer.android.com/reference/java/lang/Package`.
| Parameters ||
|---|---|
| `name` | `String`: The expected [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class, or `null` if not known
|
| `b` | `byte`: The bytes that make up the class data. The bytes in positions `off` through `off+len-1` should have the format of a valid class file as defined by The Java Virtual Machine Specification.
|
| `off` | `int`: The start offset in `b` of the class data
|
| `len` | `int`: The length of the class data
|
| `protectionDomain` | `ProtectionDomain`: The `ProtectionDomain` of the class
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The `Class` object created from the data, and `ProtectionDomain`.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassFormatError` | If the data did not contain a valid class |
| `https://developer.android.com/reference/java/lang/IndexOutOfBoundsException` | If either `off` or `len` is negative, or if `off+len` is greater than `b.length`. |
| `https://developer.android.com/reference/java/lang/NoClassDefFoundError` | If `name` is not `null` and not equal to the [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class specified by `b` |
| `https://developer.android.com/reference/java/lang/SecurityException` | If an attempt is made to add this class to a package that contains classes that were signed by a different set of certificates than this class, or if `name` begins with "`java.`" and this class loader is not the platform class loader or its ancestor. |
### defineClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final Class defineClass (String name,
ByteBuffer b,
ProtectionDomain protectionDomain)
```
Converts a `https://developer.android.com/reference/java/nio/ByteBuffer` into an instance
of class `Class`, with the given `ProtectionDomain`.
If the given `ProtectionDomain` is `null`, then a default
protection domain will be assigned to the class as
specified in the documentation for `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)`. Before the class can be used it must be resolved.
The rules about the first class defined in a package determining the
set of certificates for the package, the restrictions on class names,
and the defined package of the class
are identical to those specified in the documentation for `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)`.
An invocation of this method of the form
*cl*`.defineClass(`*name*`,`
*bBuffer*`,` *pd*`)` yields exactly the same
result as the statements
``
...
byte[] temp = new byte[bBuffer.`https://developer.android.com/reference/java/nio/Buffer#remaining()`()];
bBuffer.`https://developer.android.com/reference/java/nio/ByteBuffer#get(byte[])`(temp);
return `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)`(name, temp, 0,
temp.length, pd);
``
| Parameters ||
|---|---|
| `name` | `String`: The expected [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). of the class, or `null` if not known
|
| `b` | `ByteBuffer`: The bytes that make up the class data. The bytes from positions `b.position()` through `b.position() + b.limit() -1 ` should have the format of a valid class file as defined by The Java Virtual Machine Specification.
|
| `protectionDomain` | `ProtectionDomain`: The `ProtectionDomain` of the class, or `null`.
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The `Class` object created from the data, and `ProtectionDomain`.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassFormatError` | If the data did not contain a valid class. |
| `https://developer.android.com/reference/java/lang/NoClassDefFoundError` | If `name` is not `null` and not equal to the [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class specified by `b` |
| `https://developer.android.com/reference/java/lang/SecurityException` | If an attempt is made to add this class to a package that contains classes that were signed by a different set of certificates than this class, or if `name` begins with "`java.`". |
**See also:**
- `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)`
### defineClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
Deprecated in [API level
15](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final Class defineClass (byte[] b,
int off,
int len)
```
**This method was deprecated
in API level 15.**
Replaced by `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)`
Converts an array of bytes into an instance of class `Class`.
Before the `Class` can be used it must be resolved. This method
is deprecated in favor of the version that takes a [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) as its first argument, and is more secure.
| Parameters ||
|---|---|
| `b` | `byte`: The bytes that make up the class data. The bytes in positions `off` through `off+len-1` should have the format of a valid class file as defined by The Java Virtual Machine Specification.
|
| `off` | `int`: The start offset in `b` of the class data
|
| `len` | `int`: The length of the class data
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The `Class` object that was created from the specified class data
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassFormatError` | If the data did not contain a valid class |
| `https://developer.android.com/reference/java/lang/IndexOutOfBoundsException` | If either `off` or `len` is negative, or if `off+len` is greater than `b.length`. |
| `https://developer.android.com/reference/java/lang/SecurityException` | If an attempt is made to add this class to a package that contains classes that were signed by a different set of certificates than this class, or if an attempt is made to define a class in a package with a fully-qualified name that starts with "`java.`". |
**See also:**
- `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String,%20boolean)`
- `https://developer.android.com/reference/java/lang/ClassLoader#resolveClass(java.lang.Class)`
### defineClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final Class defineClass (String name,
byte[] b,
int off,
int len)
```
Converts an array of bytes into an instance of class `Class`.
Before the `Class` can be used it must be resolved.
This method assigns a default `https://developer.android.com/reference/java/security/ProtectionDomain` to the newly defined class. The
`ProtectionDomain` is effectively granted the same set of
permissions returned when `https://developer.android.com/reference/java/security/Policy#getPermissions(java.security.CodeSource)`
is invoked. The default protection domain is created on the first invocation
of `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)`,
and re-used on subsequent invocations.
To assign a specific `ProtectionDomain` to the class, use
the `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)` method that takes a
`ProtectionDomain` as one of its arguments.
This method defines a package in this class loader corresponding to the
package of the `Class` (if such a package has not already been defined
in this class loader). The name of the defined package is derived from
the [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class specified by
the byte array `b`.
Other properties of the defined package are as specified by `https://developer.android.com/reference/java/lang/Package`.
| Parameters ||
|---|---|
| `name` | `String`: The expected [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class, or `null` if not known
|
| `b` | `byte`: The bytes that make up the class data. The bytes in positions `off` through `off+len-1` should have the format of a valid class file as defined by The Java Virtual Machine Specification.
|
| `off` | `int`: The start offset in `b` of the class data
|
| `len` | `int`: The length of the class data
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The `Class` object that was created from the specified class data.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassFormatError` | If the data did not contain a valid class |
| `https://developer.android.com/reference/java/lang/IndexOutOfBoundsException` | If either `off` or `len` is negative, or if `off+len` is greater than `b.length`. |
| `https://developer.android.com/reference/java/lang/SecurityException` | If an attempt is made to add this class to a package that contains classes that were signed by a different set of certificates than this class (which is unsigned), or if `name` begins with "`java.`". |
**See also:**
- `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String,%20boolean)`
- `https://developer.android.com/reference/java/lang/ClassLoader#resolveClass(java.lang.Class)`
- `https://developer.android.com/reference/java/security/CodeSource`
- `https://developer.android.com/reference/java/security/SecureClassLoader`
### definePackage
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected Package definePackage (String name,
String specTitle,
String specVersion,
String specVendor,
String implTitle,
String implVersion,
String implVendor,
URL sealBase)
```
Defines a package by [name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) in this `ClassLoader`.
[Package names](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) must be unique within a class loader and
cannot be redefined or changed once created.
If a class loader wishes to define a package with specific properties,
such as version information, then the class loader should call this
`definePackage` method before calling `defineClass`.
Otherwise, the
`https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)`
method will define a package in this class loader corresponding to the package
of the newly defined class; the properties of this defined package are
specified by `https://developer.android.com/reference/java/lang/Package`.
##### API Note:
- A class loader that wishes to define a package for classes in a JAR typically uses the specification and implementation titles, versions, and vendors from the JAR's manifest. If the package is specified as [sealed](https://developer.android.com/reference/java/util/jar/Attributes.Name#SEALED) in the JAR's manifest, the `URL` of the JAR file is typically used as the `sealBase`. If classes of package `'p'` defined by this class loader are loaded from multiple JARs, the `Package` object may contain different information depending on the first class of package `'p'` defined and which JAR's manifest is read first to explicitly define package `'p'`.
It is strongly recommended that a class loader does not call this
method to explicitly define packages in *named modules* ; instead,
the package will be automatically defined when a class is [being defined](https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int,%20java.security.ProtectionDomain)).
If it is desirable to define `Package` explicitly, it should ensure
that all packages in a named module are defined with the properties
specified by `https://developer.android.com/reference/java/lang/Package`. Otherwise, some `Package` objects
in a named module may be for example sealed with different seal base.
| Parameters ||
|---|---|
| `name` | `String`: The [package name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name)
|
| `specTitle` | `String`: The specification title
|
| `specVersion` | `String`: The specification version
|
| `specVendor` | `String`: The specification vendor
|
| `implTitle` | `String`: The implementation title
|
| `implVersion` | `String`: The implementation version
|
| `implVendor` | `String`: The implementation vendor
|
| `sealBase` | `URL`: If not `null`, then this package is sealed with respect to the given code source `https://developer.android.com/reference/java/net/URL` object. Otherwise, the package is not sealed.
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Package` | The newly defined `Package` object
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if a package of the given `name` is already defined by this class loader |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if `name` is `null`. |
**See also:**
- [The JAR File Specification: Package Sealing](https://docs.oracle.com/en/java/javase/17/docs/specs/jar/jar.html#package-sealing)
### findClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected Class findClass (String name)
```
Finds the class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name).
This method should be overridden by class loader implementations that
follow the delegation model for loading classes, and will be invoked by
the `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String)` method after checking the
parent class loader for the requested class.
##### Implementation Requirements:
- The default implementation throws `ClassNotFoundException`.
| Parameters ||
|---|---|
| `name` | `String`: The [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The resulting `Class` object
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassNotFoundException` | If the class could not be found |
### findLibrary
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected String findLibrary (String libname)
```
Returns the absolute path name of a native library. The VM invokes this
method to locate the native libraries that belong to classes loaded with
this class loader. If this method returns `null`, the VM
searches the library along the path specified as the
"`java.library.path`" property.
| Parameters ||
|---|---|
| `libname` | `String`: The library name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/String` | The absolute path of the native library
|
**See also:**
- `https://developer.android.com/reference/java/lang/System#loadLibrary(java.lang.String)`
- `https://developer.android.com/reference/java/lang/System#mapLibraryName(java.lang.String)`
### findLoadedClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final Class findLoadedClass (String name)
```
Returns the class with the given [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) if this
loader has been recorded by the Java virtual machine as an initiating
loader of a class with that [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). Otherwise
`null` is returned.
| Parameters ||
|---|---|
| `name` | `String`: The [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The `Class` object, or `null` if the class has not been loaded
|
### findResource
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected URL findResource (String name)
```
Finds the resource with the given name. Class loader implementations
should override this method.
##### Implementation Requirements:
- The default implementation returns `null`.
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/net/URL` | `URL` object for reading the resource; `null` if the resource could not be found, a `URL` could not be constructed to locate the resource, the resource is in a package that is not opened unconditionally, or access to the resource is denied by the security manager.
|
### findResources
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected Enumeration findResources (String name)
```
Returns an enumeration of `https://developer.android.com/reference/java/net/URL` objects
representing all the resources with the given name. Class loader
implementations should override this method.
##### Implementation Requirements:
- The default implementation returns an enumeration that contains no elements.
| Parameters ||
|---|---|
| `name` | `String`: The resource name
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Enumeration` | An enumeration of `https://developer.android.com/reference/java/net/URL` objects for the resource. If no resources could be found, the enumeration will be empty. Resources for which a `URL` cannot be constructed, are in a package that is not opened unconditionally, or access to the resource is denied by the security manager, are not returned in the enumeration.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | If I/O errors occur |
### findSystemClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final Class findSystemClass (String name)
```
Finds a class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name),
loading it if necessary.
This method loads the class through the system class loader (see
`https://developer.android.com/reference/java/lang/ClassLoader#getSystemClassLoader()`). The `Class` object returned
might have more than one `ClassLoader` associated with it.
Subclasses of `ClassLoader` need not usually invoke this method,
because most class loaders need to override just `https://developer.android.com/reference/java/lang/ClassLoader#findClass(java.lang.String)`.
| Parameters ||
|---|---|
| `name` | `String`: The [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The `Class` object for the specified `name`
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassNotFoundException` | If the class could not be found |
**See also:**
- `https://developer.android.com/reference/java/lang/ClassLoader#ClassLoader(java.lang.ClassLoader)`
- `https://developer.android.com/reference/java/lang/ClassLoader#getParent()`
### getPackage
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
Deprecated in [API level
35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected Package getPackage (String name)
```
**This method was deprecated
in API level 35.**
If multiple class loaders delegate to each other and define classes
with the same package name, and one such loader relies on the lookup
behavior of `getPackage` to return a `Package` from
a parent loader, then the properties exposed by the `Package`
may not be as expected in the rest of the program.
For example, the `Package` will only expose annotations from the
`package-info.class` file defined by the parent loader, even if
annotations exist in a `package-info.class` file defined by
a child loader.
Finds a package by [name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) in this class loader and its ancestors.
If this class loader defines a `Package` of the given name,
the `Package` is returned. Otherwise, the ancestors of
this class loader are searched recursively (parent by parent)
for a `Package` of the given name.
| Parameters ||
|---|---|
| `name` | `String`: The [package name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name)
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Package` | The `Package` of the given name that has been defined by this class loader or its ancestors, or `null` if not found.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if `name` is `null`. |
### getPackages
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected Package[] getPackages ()
```
Returns all of the `Package`s that have been defined by
this class loader and its ancestors. The returned array may contain
more than one `Package` object of the same package name, each
defined by a different class loader in the class loader hierarchy.
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Package` | The array of `Package` objects that have been defined by this class loader and its ancestors
|
### loadClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected Class loadClass (String name,
boolean resolve)
```
Loads the class with the specified [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name). The
default implementation of this method searches for classes in the
following order:
1. Invoke `https://developer.android.com/reference/java/lang/ClassLoader#findLoadedClass(java.lang.String)` to check if the class
has already been loaded.
2. Invoke the `https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String)` method
on the parent class loader. If the parent is `null` the class
loader built into the virtual machine is used, instead.
3. Invoke the `https://developer.android.com/reference/java/lang/ClassLoader#findClass(java.lang.String)` method to find the
class.
If the class was found using the above steps, and the
`resolve` flag is true, this method will then invoke the `https://developer.android.com/reference/java/lang/ClassLoader#resolveClass(java.lang.Class)` method on the resulting `Class` object.
Subclasses of `ClassLoader` are encouraged to override `https://developer.android.com/reference/java/lang/ClassLoader#findClass(java.lang.String)`, rather than this method.
| Parameters ||
|---|---|
| `name` | `String`: The [binary name](https://developer.android.com/reference/java/lang/ClassLoader#binary-name) of the class
|
| `resolve` | `boolean`: If `true` then resolve the class
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Class` | The resulting `Class` object
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassNotFoundException` | If the class could not be found |
### registerAsParallelCapable
Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected static boolean registerAsParallelCapable ()
```
Registers the caller as
`#isRegisteredAsParallelCapable() parallel capable`.
The registration succeeds if and only if all of the following
conditions are met:
1. no instance of the caller has been created
2. all of the super classes (except class Object) of the caller are registered as parallel capable
Note that once a class loader is registered as parallel capable, there
is no way to change it back.
| Returns ||
|---|---|
| `boolean` | `true` if the caller is successfully registered as parallel capable and `false` if otherwise.
|
### resolveClass
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final void resolveClass (Class c)
```
Links the specified class. This (misleadingly named) method may be
used by a class loader to link a class. If the class `c` has
already been linked, then this method simply returns. Otherwise, the
class is linked as described in the "Execution" chapter of
The Java Language Specification.
| Parameters ||
|---|---|
| `c` | `Class`: The class to link
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | If `c` is `null`. |
**See also:**
- `https://developer.android.com/reference/java/lang/ClassLoader#defineClass(java.lang.String,%20byte[],%20int,%20int)`
### setSigners
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected final void setSigners (Class c,
Object[] signers)
```
Sets the signers of a class. This should be invoked after defining a
class.
| Parameters ||
|---|---|
| `c` | `Class`: The `Class` object
|
| `signers` | `Object`: The signers for the class
|