删除活动堆栈

Question

I have 3 activities: A->B->C

The user starts from activity A. When going to B he can press back and return to A. But... When user goes to C from B. I wish that A and B will be removed and user will exit the app when clicking back.

I tried:

Intent intent = new Intent(B.this, C.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);

but on back it still goes to B. If doing so:

Intent intent = new Intent(VerifyPhoneActivity.this, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
finish();

The user goes back to A, so.. It is not what I need.

Answer 1

Override onBackPressed() in Activity C

@Override
public void onBackPressed() {
    finishAffinity();
}

This will cause all Activity s running in the same task to finish. If the user starts the app again by tapping on it in the recent tasks window, Activity A will be shown.

Answer 2

Start B activity with startActivityForResult() :

Intent intent = new Intent(A.this, B.class);
startActivityForResult(intent, 100);

and override in class A startActivityForResult() :

@Override 
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    if (requestCode == 100) {
        if (resultCode == 1) {
            finish();
        }
    }
}

Now in B class set the result to be sent back to activity A :

Intent intent = new Intent(VerifyPhoneActivity.this, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
setResult(1);
finish();

Answer 3

100% working. try to start Activity C like this. Intent intent = new Intent(this,ActivityC.class); intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); startActivity();

Answer 4

If I understood you right, You could achieve this is using SharedPreferences:

In Your Activity A add this:

public class ActivityA extends AppCompatActivity {

SharedPreferences prefs;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);

    if (savedInstanceState == null){
        SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
        editor.putBoolean("CloseApp", false);
        editor.commit();
    }

}

@Override
protected void onResume() {
    super.onResume();
    boolean finish = prefs.getBoolean("CloseApp", false);
    if (finish){
        this.finish();
    }
}

In Activity B:

public class ActivityB extends AppCompatActivity {

SharedPreferences prefs;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);

    prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);

}

@Override
protected void onResume() {
    super.onResume();

    boolean finish = prefs.getBoolean("CloseApp", false);
    if (finish){
        this.finish();
    }
}

And Activity C:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_third);

    SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
    editor.putBoolean("CloseApp", true);
    editor.commit();
}

@Override
public void onBackPressed() {
    super.onBackPressed();
    this.finish();
}

That should work.

Answer 5

you can just write this in Activity C if your application work from JELLY_BEAN to up .

  @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    @Override
    public void onBackPressed() {
        super.onBackPressed();
        finishAffinity();
    }

if your app work under JELLY_BEAN you can use this solution :

Activity C :

   @Override
    public void onBackPressed() {
        Intent i = new Intent(C.this,A.class);
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        i.putExtra("BackFromC",true);
        startActivity(i);
        super.onBackPressed();
    }

Activity A in onCreate :

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_a);

        if(getIntent() != null){
            if(getIntent().getBooleanExtra("BackFromC",false)){
                finish();
            }
        }

        ... your Code 
    }