Added in API level 1

android.os

Provides basic operating system services, message passing, and inter-process communication on the device.

Interfaces

CancellationSignal.OnCancelListener Listens for cancellation. 
FileUtils.ProgressListener Listener that is called periodically as progress is made. 
Handler.Callback Callback interface you can use when instantiating a Handler to avoid having to implement your own subclass of Handler. 
IBinder Base interface for a remotable object, the core part of a lightweight remote procedure call mechanism designed for high performance when performing in-process and cross-process calls. 
IBinder.DeathRecipient Interface for receiving a callback when the process hosting an IBinder has gone away. 
IInterface Base class for Binder interfaces. 
MessageQueue.IdleHandler Callback interface for discovering when a thread is going to block waiting for more messages. 
MessageQueue.OnFileDescriptorEventListener A listener which is invoked when file descriptor related events occur. 
OutcomeReceiver<R, E extends Throwable> Callback interface intended for use when an asynchronous operation may result in a failure. 
Parcelable Interface for classes whose instances can be written to and restored from a Parcel. 
Parcelable.ClassLoaderCreator<T> Specialization of Creator that allows you to receive the ClassLoader the object is being created in. 
Parcelable.Creator<T> Interface that must be implemented and provided as a public CREATOR field that generates instances of your Parcelable class from a Parcel. 
ParcelFileDescriptor.OnCloseListener Callback indicating that a ParcelFileDescriptor has been closed. 
PowerManager.OnThermalStatusChangedListener Listener passed to PowerManager.addThermalStatusListener and PowerManager.removeThermalStatusListener to notify caller of thermal status has changed. 
PowerManager.WakeLockStateListener A listener interface to get notified when the wakelock is enabled/disabled. 
RecoverySystem.ProgressListener Interface definition for a callback to be invoked regularly as verification proceeds. 
StrictMode.OnThreadViolationListener When #StrictMode.ThreadPolicy.Builder.penaltyListener(Executor, OnThreadViolationListener) is enabled, the listener is called on the provided executor when a Thread violation occurs. 
StrictMode.OnVmViolationListener When #StrictMode.VmPolicy.Builder.penaltyListener(Executor, OnVmViolationListener) is enabled, the listener is called on the provided executor when a VM violation occurs. 

Classes

AsyncTask<Params, Progress, Result> This class was deprecated in API level 30. Use the standard java.util.concurrent or Kotlin concurrency utilities instead. 
BaseBundle A mapping from String keys to values of various types. 
BatteryManager The BatteryManager class contains strings and constants used for values in the Intent.ACTION_BATTERY_CHANGED Intent, and provides a method for querying battery and charging properties. 
Binder Base class for a remotable object, the core part of a lightweight remote procedure call mechanism defined by IBinder. 
BugreportManager Class that provides a privileged API to capture and consume bugreports. 
BugreportManager.BugreportCallback An interface describing the callback for bugreport progress and status. 
Build Information about the current build, extracted from system properties. 
Build.Partition Build information for a particular device partition. 
Build.VERSION Various version strings. 
Build.VERSION_CODES Enumeration of the currently known SDK version codes. 
Build.VERSION_CODES_FULL Enumeration of the currently known SDK major and minor version codes. 
Bundle A mapping from String keys to various Parcelable values. 
CancellationSignal Provides the ability to cancel an operation in progress. 
CombinedVibration A CombinedVibration describes a combination of haptic effects to be performed by one or more Vibrators. 
CombinedVibration.ParallelCombination A combination of haptic effects that should be played in multiple vibrators in parallel. 
ConditionVariable Class that implements the condition variable locking paradigm. 
CountDownTimer Schedule a countdown until a time in the future, with regular notifications on intervals along the way. 
CpuUsageInfo CPU usage information per core. 
Debug Provides various debugging methods for Android applications, including tracing and allocation counts. 
Debug.InstructionCount This class was deprecated in API level 23. Instruction counting is no longer supported. 
Debug.MemoryInfo This class is used to retrieved various statistics about the memory mappings for this process. 
DropBoxManager Enqueues chunks of data (from various sources -- application crashes, kernel log records, etc.). 
DropBoxManager.Entry A single entry retrieved from the drop box. 
Environment Provides access to environment variables. 
FileObserver Monitors files (using inotify) to fire an event after files are accessed or changed by any process on the device (including this one). 
FileUtils Utility methods useful for working with files. 
Handler A Handler allows you to send and process Message and Runnable objects associated with a thread's MessageQueue. 
HandlerThread A Thread that has a Looper. 
HardwarePropertiesManager The HardwarePropertiesManager class provides a mechanism of accessing hardware state of a device: CPU, GPU and battery temperatures, CPU usage per core, fan speed, etc. 
LocaleList LocaleList is an immutable list of Locales, typically used to keep an ordered list of user preferences for locales. 
Looper Class used to run a message loop for a thread. 
MemoryFile MemoryFile is a wrapper for SharedMemory which can optionally be set to purgeable. 
Message Defines a message containing a description and arbitrary data object that can be sent to a Handler. 
MessageQueue Low-level class holding the list of messages to be dispatched by a Looper. 
Messenger Reference to a Handler, which others can use to send messages to it. 
Parcel Container for a message (data and object references) that can be sent through an IBinder. 
ParcelFileDescriptor The FileDescriptor returned by Parcel.readFileDescriptor, allowing you to close it when done with it. 
ParcelFileDescriptor.AutoCloseInputStream An InputStream you can create on a ParcelFileDescriptor, which will take care of calling ParcelFileDescriptor.close() for you when the stream is closed. 
ParcelFileDescriptor.AutoCloseOutputStream An OutputStream you can create on a ParcelFileDescriptor, which will take care of calling ParcelFileDescriptor.close() for you when the stream is closed. 
ParcelUuid This class is a Parcelable wrapper around UUID which is an immutable representation of a 128-bit universally unique identifier. 
PatternMatcher A simple pattern matcher, which is safe to use on untrusted data: it does not provide full reg-exp support, only simple globbing that can not be used maliciously. 
PerformanceHintManager The PerformanceHintManager allows apps to send performance hint to system. 
PerformanceHintManager.Session A Session represents a group of threads with an inter-related workload such that hints for their performance should be considered as a unit. 
PersistableBundle A mapping from String keys to values of various types. 
PowerManager This class lets you query and request control of aspects of the device's power state. 
PowerManager.WakeLock A wake lock is a mechanism to indicate that your application needs to have the device stay on. 
PowerMonitor A PowerMonitor represents either an ODPM rail (on-device power rail monitor) or a modeled energy consumer. 
PowerMonitorReadings A collection of energy measurements from Power Monitors. 
Process Tools for managing OS processes. 
ProfilingManager

This class allows the caller to request profiling and listen for results. 

ProfilingResult Encapsulates results of a single profiling request operation. 
ProxyFileDescriptorCallback Callback that handles file system requests from ProxyFileDescriptor. 
RecoverySystem RecoverySystem contains methods for interacting with the Android recovery system (the separate partition that can be used to install system updates, wipe user data, etc.) 
RemoteCallbackList<E extends IInterface> Takes care of the grunt work of maintaining a list of remote interfaces, typically for the use of performing callbacks from a Service to its clients. 
ResultReceiver Generic interface for receiving a callback result from someone. 
SecurityStateManager SecurityStateManager provides the functionality to query the security status of the system and platform components. 
SharedMemory SharedMemory enables the creation, mapping, and protection control over anonymous shared memory. 
StatFs Retrieve overall information about the space on a filesystem. 
StrictMode StrictMode is a developer tool which detects things you might be doing by accident and brings them to your attention so you can fix them. 
StrictMode.ThreadPolicy StrictMode policy applied to a certain thread. 
StrictMode.ThreadPolicy.Builder Creates ThreadPolicy instances. 
StrictMode.VmPolicy StrictMode policy applied to all threads in the virtual machine's process. 
StrictMode.VmPolicy.Builder Creates VmPolicy instances. 
SystemClock Core timekeeping facilities. 
TestLooperManager Blocks a looper from executing any messages, and allows the holder of this object to control when and which messages get executed until it is released. 
TokenWatcher A TokenWatcher watches a collection of IBinders. 
Trace Writes trace events to the system trace buffer. 
UserHandle Representation of a user on the device. 
UserManager Manages users and user details on a multi-user system. 
VibrationAttributes Encapsulates a collection of attributes describing information about a vibration. 
VibrationAttributes.Builder Builder class for VibrationAttributes objects. 
VibrationEffect A VibrationEffect describes a haptic effect to be performed by a Vibrator. 
VibrationEffect.Composition A composition of haptic elements that are combined to be playable as a single VibrationEffect. 
Vibrator Class that operates the vibrator on the device. 
VibratorManager Provides access to all vibrators from the device, as well as the ability to run them in a synchronized fashion. 
WorkDuration WorkDuration contains the measured time in nano seconds of the workload in each component, see PerformanceHintManager.Session#reportActualWorkDuration(WorkDuration). 
WorkSource Describes the source of some work that may be done by someone else. 

Enums

AsyncTask.Status Indicates the current status of the task. 

Exceptions

BadParcelableException Exception thrown when a Parcelable is malformed or otherwise invalid. 
DeadObjectException The object you are calling has died, because its hosting process no longer exists, or there has been a low-level binder error. 
DeadSystemException The core Android system has died and is going through a runtime restart. 
FileUriExposedException The exception that is thrown when an application exposes a file:// Uri to another app. 
LimitExceededException Indicates that the app has exceeded a limit set by the System. 
NetworkOnMainThreadException The exception that is thrown when an application attempts to perform a networking operation on its main thread. 
OperationCanceledException An exception type that is thrown when an operation in progress is canceled. 
ParcelFileDescriptor.FileDescriptorDetachedException Exception that indicates that the file descriptor was detached. 
ParcelFormatException The contents of a Parcel (usually during unmarshalling) does not contain the expected data. 
RemoteException Parent exception for all Binder remote-invocation errors Note: not all exceptions from binder services will be subclasses of this. 
TransactionTooLargeException The Binder transaction failed because it was too large. 
UserManager.UserOperationException Thrown to indicate user operation failed.