java.lang.Object | |||
↳ | android.content.Context | ||
↳ | android.content.ContextWrapper | ||
↳ | android.app.Application |
Known Direct Subclasses
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Base class for those who need to maintain global application state. You can provide your own implementation by specifying its name in your AndroidManifest.xml's <application> tag, which will cause that class to be instantiated for you when the process for your application/package is created.
There is normally no need to subclass Application. In
most situation, static singletons can provide the same functionality in a
more modular way. If your singleton needs a global context (for example
to register broadcast receivers), the function to retrieve it can be
given a Context
which internally uses
Context.getApplicationContext()
when first constructing the singleton.
Nested Classes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Application.ActivityLifecycleCallbacks |
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Inherited Constants | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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From class
android.content.Context
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From interface
android.content.ComponentCallbacks2
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Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Called by the system when the device configuration changes while your
component is running.
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Called when the application is starting, before any other application
objects have been created.
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This is called when the overall system is running low on memory, and
would like actively running process to try to tighten their belt.
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This method is for use in emulated process environments.
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Called when the operating system has determined that it is a good
time for a process to trim unneeded memory from its process.
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Add a new
ComponentCallbacks to the base application of the
Context, which will be called at the same times as the ComponentCallbacks
methods of activities and other components are called. | |||||||||||
Remove a
ComponentCallbacks objec that was previously registered
with registerComponentCallbacks(ComponentCallbacks) . |
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Inherited Methods | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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From class
android.content.ContextWrapper
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From class
android.content.Context
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From class
java.lang.Object
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From interface
android.content.ComponentCallbacks
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From interface
android.content.ComponentCallbacks2
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Called by the system when the device configuration changes while your component is running. Note that, unlike activities, other components are never restarted when a configuration changes: they must always deal with the results of the change, such as by re-retrieving resources.
At the time that this function has been called, your Resources object will have been updated to return resource values matching the new configuration.
newConfig | The new device configuration. |
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Called when the application is starting, before any other application objects have been created. Implementations should be as quick as possible (for example using lazy initialization of state) since the time spent in this function directly impacts the performance of starting the first activity, service, or receiver in a process. If you override this method, be sure to call super.onCreate().
This is called when the overall system is running low on memory, and would like actively running process to try to tighten their belt. While the exact point at which this will be called is not defined, generally it will happen around the time all background process have been killed, that is before reaching the point of killing processes hosting service and foreground UI that we would like to avoid killing.
Applications that want to be nice can implement this method to release any caches or other unnecessary resources they may be holding on to. The system will perform a gc for you after returning from this method.
This method is for use in emulated process environments. It will never be called on a production Android device, where processes are removed by simply killing them; no user code (including this callback) is executed when doing so.
Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process. This will happen for example when it goes in the background and there is not enough memory to keep as many background processes running as desired. You should never compare to exact values of the level, since new intermediate values may be added -- you will typically want to compare if the value is greater or equal to a level you are interested in.
To retrieve the processes current trim level at any point, you can
use ActivityManager.getMyMemoryState(RunningAppProcessInfo)
.
level | The context of the trim, giving a hint of the amount of
trimming the application may like to perform. May be
TRIM_MEMORY_COMPLETE , TRIM_MEMORY_MODERATE ,
TRIM_MEMORY_BACKGROUND , TRIM_MEMORY_UI_HIDDEN ,
TRIM_MEMORY_RUNNING_CRITICAL , TRIM_MEMORY_RUNNING_LOW ,
or TRIM_MEMORY_RUNNING_MODERATE .
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Add a new ComponentCallbacks
to the base application of the
Context, which will be called at the same times as the ComponentCallbacks
methods of activities and other components are called. Note that you
must be sure to use unregisterComponentCallbacks(ComponentCallbacks)
when
appropriate in the future; this will not be removed for you.
callback | The interface to call. This can be either a
ComponentCallbacks or ComponentCallbacks2 interface.
|
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Remove a ComponentCallbacks
objec that was previously registered
with registerComponentCallbacks(ComponentCallbacks)
.