Android developers - ActivityLifecycleCallbacks use

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What ActivityLifecycleCallbacks that?

• Application through this interface provides a callback method used to allow developers to Activity lifecycle events for centralized treatment.

Why ActivityLifecycleCallbacks?

• For the past monitoring Activity lifecycle event code, you may do so, rewrite onResume each Acivity of (), and then for statistical processing:
  [java] view plain copy

  1. @Override  
  2. protected void onResume() {  
  3.   super.onResume();  
  4.   // TODO processing and statistical code  
  5.   Log.v(TAG, "onResume");  
  6.   Logger.v(TAG, "onResume");  
  7.   Logging.v(TAG, "onResume");  
  8.   ...  
  9. }  
  
  
• ActivityLifecycleCallbacks callback interface to simplify this tedious process, make a unified process in a class

ActivityLifecycleCallbacks how to use?

• android.app.Application.ActivityLifecycleCallbacks
• Requirements API 14+ (Android 4.0+)
• Inheritance Application
  [java] view plain copy

  1. public class BaseApplication extends Application  

  
  
• Custom Application hired in the AndroidManifest
  [html] view plain copy

  1. <application android:name=".global.BaseApplication"  

  
  

• Application of rewriting onCreate () method, or the non-parametric method of construction of the Application, calls Application.registerActivityLifecycleCallbacks () method, and implement the interface ActivityLifecycleCallbacks

  [java] view plain copy

  1. public void onCreate() {  
  2.   super.onCreate();  
  3.   this.registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {  
  4.    
  5.     @Override  
  6.     public void onActivityStopped(Activity activity) {  
  7.         Logger.v(activity, "onActivityStopped");  
  8.     }  
  9.    
  10.     @Override  
  11.     public void onActivityStarted(Activity activity) {  
  12.         Logger.v(activity, "onActivityStarted");  
  13.     }  
  14.    
  15.     @Override  
  16.     public void onActivitySaveInstanceState(Activity activity, Bundle outState) {  
  17.         Logger.v(activity, "onActivitySaveInstanceState");  
  18.     }  
  19.    
  20.     @Override  
  21.     public void onActivityResumed(Activity activity) {  
  22.         Logger.v(activity, "onActivityResumed");  
  23.     }  
  24.    
  25.     @Override  
  26.     public void onActivityPaused(Activity activity) {  
  27.         Logger.v(activity, "onActivityPaused");  
  28.     }  
  29.    
  30.     @Override  
  31.     public void onActivityDestroyed(Activity activity) {  
  32.         Logger.v(activity, "onActivityDestroyed");  
  33.     }  
  34.    
  35.     @Override  
  36.     public void onActivityCreated(Activity activity, Bundle savedInstanceState) {  
  37.         Logger.v(activity, "onActivityCreated");  
  38.     }  
  39.   });  
  40. };  
  
  

• Operating results (Logcat log)

  [plain] view plain copy

  1. 10-21 14:32:57.722: V/WelcomeActivity(8085): onActivityCreated  
  2. 10-21 14:32:57.762: V/WelcomeActivity(8085): onActivityStarted  
  3. 10-21 14:32:57.762: V/WelcomeActivity(8085): onActivityResumed  
  4. 10-21 14:32:59.164: V/WelcomeActivity(8085): onActivityPaused  
  5. 10-21 14:32:59.194: V/MainActivity(8085): onActivityCreated  
  6. 10-21 14:32:59.224: V/MainActivity(8085): onActivityStarted  
  7. 10-21 14:32:59.224: V/MainActivity(8085): onActivityResumed  
  8. 10-21 14:32:59.735: V/WelcomeActivity(8085): onActivityStopped  
  9. 10-21 14:32:59.735: V/WelcomeActivity(8085): onActivityDestroyed  
  10. 10-21 14:33:06.502: V/MainActivity(8085): onActivityPaused  
  11. 10-21 14:33:06.612: V/MainActivity(8085): onActivityStopped  
  12. 10-21 14:33:06.612: V/MainActivity(8085): onActivityDestroyed  
  
  

ActivityLifecycleCallbacks expand usage

• The only attempt to use the Log On the logging facility for a brief test, when To meet more complex statistical or debugging requirements, this method may significantly reduce the amount of code is inserted, improve efficiency

• API only provides the interface callbacks on the 14+ version, how the system uses Android 4.0?

• API only stay for a few Activity lifecycle events of the above-mentioned callback interfaces, may have been unable to meet the increasing transition to use Fragment of today's needs, how to apply LifecycleCallbacks on a larger scale?