# Dictionary Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary:[Ctors](https://developer.android.com/reference/java/util/Dictionary#pubctors)\|[Methods](https://developer.android.com/reference/java/util/Dictionary#pubmethods)\|[Inherited Methods](https://developer.android.com/reference/java/util/Dictionary#inhmethods) # Dictionary ` public abstract class Dictionary ` ` extends `[Object](https://developer.android.com/reference/java/lang/Object)` `` ` |---|------------------------------| | [java.lang.Object](https://developer.android.com/reference/java/lang/Object) || | ↳ | java.util.Dictionary\ | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | Known direct subclasses [Hashtable](https://developer.android.com/reference/java/util/Hashtable)\ |----------------------------------------------------------------------------------|----------------------------------------------------------------| | [Hashtable](https://developer.android.com/reference/java/util/Hashtable)\ | This class implements a hash table, which maps keys to values. | | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | Known indirect subclasses [AuthProvider](https://developer.android.com/reference/java/security/AuthProvider),[Properties](https://developer.android.com/reference/java/util/Properties),[Provider](https://developer.android.com/reference/java/security/Provider) |------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------| | [AuthProvider](https://developer.android.com/reference/java/security/AuthProvider) | Legacy security code; do not use. | | [Properties](https://developer.android.com/reference/java/util/Properties) | The`Properties`class represents a persistent set of properties. | | [Provider](https://developer.android.com/reference/java/security/Provider) | This class represents a "provider" for the Java Security API, where a provider implements some or all parts of Java Security. | |
*** ** * ** *** The`Dictionary`class is the abstract parent of any class, such as`Hashtable`, which maps keys to values. Every key and every value is an object. In any one`Dictionary`object, every key is associated with at most one value. Given a`Dictionary`and a key, the associated element can be looked up. Any non-`null`object can be used as a key and as a value. As a rule, the`equals`method should be used by implementations of this class to decide if two keys are the same. **NOTE: This class is obsolete. New implementations should implement the Map interface, rather than extending this class.** **See also:** - [Map](https://developer.android.com/reference/java/util/Map) - [Object.equals(java.lang.Object)](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)) - [Object.hashCode()](https://developer.android.com/reference/java/lang/Object#hashCode()) - [Hashtable](https://developer.android.com/reference/java/util/Hashtable) ## Summary | ### Public constructors || |-------------------------------------------------------------------------------------------------------------------|---| | ` `[Dictionary](https://developer.android.com/reference/java/util/Dictionary#Dictionary())`() ` Sole constructor. | | ### Public methods || |-----------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` abstract `[Enumeration](https://developer.android.com/reference/java/util/Enumeration)`` | ` `[elements](https://developer.android.com/reference/java/util/Dictionary#elements())`() ` Returns an enumeration of the values in this dictionary. | | ` abstract V` | ` `[get](https://developer.android.com/reference/java/util/Dictionary#get(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` key) ` Returns the value to which the key is mapped in this dictionary. | | ` abstract boolean` | ` `[isEmpty](https://developer.android.com/reference/java/util/Dictionary#isEmpty())`() ` Tests if this dictionary maps no keys to value. | | ` abstract `[Enumeration](https://developer.android.com/reference/java/util/Enumeration)`` | ` `[keys](https://developer.android.com/reference/java/util/Dictionary#keys())`() ` Returns an enumeration of the keys in this dictionary. | | ` abstract V` | ` `[put](https://developer.android.com/reference/java/util/Dictionary#put(K,%20V))`(K key, V value) ` Maps the specified`key`to the specified`value`in this dictionary. | | ` abstract V` | ` `[remove](https://developer.android.com/reference/java/util/Dictionary#remove(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` key) ` Removes the`key`(and its corresponding`value`) from this dictionary. | | ` abstract int` | ` `[size](https://developer.android.com/reference/java/util/Dictionary#size())`() ` Returns the number of entries (distinct keys) in this dictionary. | | ### Inherited methods | |-----------------------|---| | From class` `[java.lang.Object](https://developer.android.com/reference/java/lang/Object)` ` |--------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` `[Object](https://developer.android.com/reference/java/lang/Object) | ` `[clone](https://developer.android.com/reference/java/lang/Object#clone())`() ` Creates and returns a copy of this object. | | ` boolean` | ` `[equals](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` obj) ` Indicates whether some other object is "equal to" this one. | | ` void` | ` `[finalize](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 `[Class](https://developer.android.com/reference/java/lang/Class)`` | ` `[getClass](https://developer.android.com/reference/java/lang/Object#getClass())`() ` Returns the runtime class of this`Object`. | | ` int` | ` `[hashCode](https://developer.android.com/reference/java/lang/Object#hashCode())`() ` Returns a hash code value for the object. | | ` final void` | ` `[notify](https://developer.android.com/reference/java/lang/Object#notify())`() ` Wakes up a single thread that is waiting on this object's monitor. | | ` final void` | ` `[notifyAll](https://developer.android.com/reference/java/lang/Object#notifyAll())`() ` Wakes up all threads that are waiting on this object's monitor. | | ` `[String](https://developer.android.com/reference/java/lang/String) | ` `[toString](https://developer.android.com/reference/java/lang/Object#toString())`() ` Returns a string representation of the object. | | ` final void` | ` `[wait](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` | ` `[wait](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` | ` `[wait](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*. | || ## Public constructors ### Dictionary Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public Dictionary () ``` Sole constructor. (For invocation by subclass constructors, typically implicit.)
## Public methods ### elements Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract Enumeration elements () ``` Returns an enumeration of the values in this dictionary. The general contract for the`elements`method is that an`Enumeration`is returned that will generate all the elements contained in entries in this dictionary.
| Returns || |-----------------------------------------------------------------------------------|---------------------------------------------------------| | [Enumeration](https://developer.android.com/reference/java/util/Enumeration)`` | an enumeration of the values in this dictionary.
| **See also:** - [keys()](https://developer.android.com/reference/java/util/Dictionary#keys()) - [Enumeration](https://developer.android.com/reference/java/util/Enumeration) ### get Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract V get (Object key) ``` Returns the value to which the key is mapped in this dictionary. The general contract for the`isEmpty`method is that if this dictionary contains an entry for the specified key, the associated value is returned; otherwise,`null`is returned.
| Parameters || |-------|-----------------------------------------------------------------------------------------------------------| | `key` | `Object`: a key in this dictionary.`null`if the key is not mapped to any value in this dictionary.
| | Returns || |-----|-----------------------------------------------------------------| | `V` | the value to which the key is mapped in this dictionary;
| | Throws || |------------------------------------------------------------------------------------------------|----------------------| | [NullPointerException](https://developer.android.com/reference/java/lang/NullPointerException) | if the`key`is`null`. | **See also:** - [put(java.lang.Object, java.lang.Object)](https://developer.android.com/reference/java/util/Dictionary#put(K,%20V)) ### isEmpty Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract boolean isEmpty () ``` Tests if this dictionary maps no keys to value. The general contract for the`isEmpty`method is that the result is true if and only if this dictionary contains no entries.
| Returns || |-----------|--------------------------------------------------------------------------| | `boolean` | `true`if this dictionary maps no keys to values;`false`otherwise.
| ### keys Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract Enumeration keys () ``` Returns an enumeration of the keys in this dictionary. The general contract for the keys method is that an`Enumeration`object is returned that will generate all the keys for which this dictionary contains entries.
| Returns || |-----------------------------------------------------------------------------------|-------------------------------------------------------| | [Enumeration](https://developer.android.com/reference/java/util/Enumeration)`` | an enumeration of the keys in this dictionary.
| **See also:** - [elements()](https://developer.android.com/reference/java/util/Dictionary#elements()) - [Enumeration](https://developer.android.com/reference/java/util/Enumeration) ### put Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract V put (K key, V value) ``` Maps the specified`key`to the specified`value`in this dictionary. Neither the key nor the value can be`null`. If this dictionary already contains an entry for the specified`key`, the value already in this dictionary for that`key`is returned, after modifying the entry to contain the new element. If this dictionary does not already have an entry for the specified`key`, an entry is created for the specified`key`and`value`, and`null`is returned. The`value`can be retrieved by calling the`get`method with a`key`that is equal to the original`key`.
| Parameters || |---------|--------------------------------| | `key` | `K`: the hashtable key.
| | `value` | `V`: the value.
| | Returns || |-----|-------------------------------------------------------------------------------------------------------------------------------| | `V` | the previous value to which the`key`was mapped in this dictionary, or`null`if the key did not have a previous mapping.
| | Throws || |------------------------------------------------------------------------------------------------|-------------------------------| | [NullPointerException](https://developer.android.com/reference/java/lang/NullPointerException) | if the`key`or`value`is`null`. | **See also:** - [Object.equals(java.lang.Object)](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)) - [get(java.lang.Object)](https://developer.android.com/reference/java/util/Dictionary#get(java.lang.Object)) ### remove Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract V remove (Object key) ``` Removes the`key`(and its corresponding`value`) from this dictionary. This method does nothing if the`key`is not in this dictionary.
| Parameters || |-------|----------------------------------------------------| | `key` | `Object`: the key that needs to be removed.
| | Returns || |-----|------------------------------------------------------------------------------------------------------------------| | `V` | the value to which the`key`had been mapped in this dictionary, or`null`if the key did not have a mapping.
| | Throws || |------------------------------------------------------------------------------------------------|------------------| | [NullPointerException](https://developer.android.com/reference/java/lang/NullPointerException) | if`key`is`null`. | ### size Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) ``` public abstract int size () ``` Returns the number of entries (distinct keys) in this dictionary.
| Returns || |-------|-----------------------------------------------| | `int` | the number of keys in this dictionary.
|