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.
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Application.ActivityLifecycleCallbacks | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Application.OnProvideAssistDataListener |
Callback interface for use with
registerOnProvideAssistDataListener(Application.OnProvideAssistDataListener)
and
unregisterOnProvideAssistDataListener(Application.OnProvideAssistDataListener)
.
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[Expand]
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 activity, service,
or receiver objects (excluding content providers) have been created.
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This is called when the overall system is running low on memory, and
actively running processes should trim their memory usage.
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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.
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Remove a
ComponentCallbacks
object that was previously registered
with
registerComponentCallbacks(ComponentCallbacks)
.
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[Expand]
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.
For more information, read Handling Runtime Changes .
newConfig | The new device configuration. |
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Called when the application is starting, before any activity, service, or receiver objects (excluding content providers) 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 actively running processes should trim their memory usage. While the exact point at which this will be called is not defined, generally it will happen when 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.
You should implement this method to release any caches or other unnecessary resources you may be holding on to. The system will perform a garbage collection for you after returning from this method.
Preferably, you should implement
onTrimMemory(int)
from
ComponentCallbacks2
to incrementally unload your resources based on various
levels of memory demands. That API is available for API level 14 and higher, so you should
only use this
onLowMemory()
method as a fallback for older versions, which can be
treated the same as
onTrimMemory(int)
with the
TRIM_MEMORY_COMPLETE
level.
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
object that was previously registered
with
registerComponentCallbacks(ComponentCallbacks)
.