Android安全退出應用程序

既然上面介紹的三種方法都沒有效果，那麼怎麼才能退出應用程序呢？
就是自定義一個Application,在該Application中去定義一個List的集合來記錄中每一個開啟的Activity，在退出的時候去遍歷這個List集合，然後挨個的進行mActivity.finish()方法，這要求在每開啟一個Activity的時候都加入到List集合中，並且在Activity退出的時候從List集合中將其移除。
```java public class Activity01 extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    MyApp myApp = (MyApp) getApplication();
    myApp.activies.add(this);
}

@Override
protected void onDestroy() {
    super.onDestroy();
    MyApp myApp = (MyApp) getApplication();
    myApp.activies.remove(this);
}

public void click1(View view){
    Intent intent = new Intent(this,Activity01.class);
    startActivity(intent);
}
public void click2(View view){
    Intent intent = new Intent(this,Activity02.class);
    startActivity(intent);
}

public void exit(View view){
    MyApp myApp = (MyApp) getApplication();
     for(Activity ac : myApp.activies){
         ac.finish();
     }
}

}

public class Activity02 extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main2);
    MyApp myApp = (MyApp) getApplication();
    myApp.activies.add(this);
}

public void click1(View view) {
    Intent intent = new Intent(this, Activity01.class);
    startActivity(intent);
}

public void click2(View view) {
    Intent intent = new Intent(this, Activity02.class);
    startActivity(intent);
}

public void exit(View view) {
    MyApp myApp = (MyApp) getApplication();
    for (Activity ac : myApp.activies) {
        ac.finish();
    }
}

@Override
protected void onDestroy() {
    super.onDestroy();
    MyApp myApp = (MyApp) getApplication();
    myApp.activies.remove(this);
}

}

public class MyApp extends Application { //存放當前應用程序裡面打開的所有的activity public List activies; @Override public void onCreate() { activies = new ArrayList(); super.onCreate(); } }