監聽Android程序前後臺切換

本Application在Api 14(Android 4.0)以上實現監聽程序在前臺運行還是在後臺運行. import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.app.Application; import android.os.Bundle; import android.widget.Toast; public class App extends Application { List<activity> list = new ArrayList<activity>(); @Override public void onCreate() { super.onCreate(); initListener(); } private void initListener() { ActivityLifecycleCallbacks callbacks = new ActivityLifecycleCallbacks() { @Override public void onActivityStopped(Activity activity) { list.remove(activity); if (list.size() == 0) { Toast.makeText(App.this, "進入後臺", Toast.LENGTH_SHORT).show(); } } @Override public void onActivityStarted(Activity activity) { list.add(activity); } @Override public void onActivitySaveInstanceState(Activity activity, Bundle outState) { } @Override public void onActivityResumed(Activity activity) { } @Override public void onActivityPaused(Activity activity) { } @Override public void onActivityDestroyed(Activity activity) { } @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { if (list.size() == 0) { Toast.makeText(App.this, "進入前臺", Toast.LENGTH_SHORT).show(); } } }; this.registerActivityLifecycleCallbacks(callbacks); } } </activity></activity>