Android app restarts when opened by clicking app icon

问题

Scenario :

I open my app by clicking icon, do something, navigate through activities, pause the app by clicking home button.

Case 1:

If I open my app by clicking icon again, the app restarts from the first activity.

Case 2:

If I open my app from recently open apps (in 4.0 by pressing menu button and selecting my app) it starts from the paused state.

I want the behavior 2 always to occur, don't want my app to restart every time when it is opened by clicking icon.

I have compared my manifest file with other apps and they are similar to mine, but behave differently (i.e like 2nd case which i want).

Edit:

This has been asked here : App completely restarting when launched by icon press in launcher

but no answers :(

回答1:

I found it. I had set a flag android:launchMode="singleTask" in my activity flag. I deleted that code.

I also added onsaveInstance method to all the activities in my code and it's working now!

Thanks :)

回答2:

Add this to your launcher activity:

if (!isTaskRoot()) {
    finish();
    return; 
}
super.onCreate(savedInstanceState);

回答3:

In current activity set some image which needs to be displayed for 2 seconds like below.

ImageView im = new ImageView(this);
im.setImageResource(set your image);
setContentView(im);
intentMainScreen = new Intent(getApplicationContext(), MainScreen.class);
Handler x = new Handler();
x.postDelayed(new splashhandler(), 2000);

Then start your activity in the SplashHandler class (which implements runnable and call start activity in run method).

It will display your Splash screen for 2 seconds and start another activity.

回答4:

Try to replace you splash Activity code with this code..

public class Splash extends Activity {

protected boolean _active = true;
protected int _splashTime = 2000;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.splash);

    Thread splashTread = new Thread() {
        @Override
        public void run() {
            try {
                int waited = 0;
                while (_active && (waited < _splashTime)) {
                    sleep(100);
                    if (_active) {
                        waited += 100;
                    }
                }
            } catch (InterruptedException e) {
                e.toString();
            } finally {
                Intent intent = new Intent(getApplicationContext(),
                        MainActivity.class);
                startActivity(intent);
                finish();
            }
        }
    };

    splashTread.start();
}

@Override
protected void onPause() {
    super.onPause();
}

@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
//      super.onBackPressed();
}
}

来源：https://stackoverflow.com/questions/17545924/android-app-restarts-when-opened-by-clicking-app-icon