Android: how to quit an activity without closing it when click on back button?

Question

I have a subActivity that can be open from my mainActivity.

For some reasons, when the user clicks on the back button go back to my mainActivity, I want my subActivity to remain open in background in order to be able to come back for later.

Questions:

• how to avoid to close the subActivity when the user clicks back ?
• how to come back to the mainActivity without restarting it ?
• how to come back later to my opened activity without re-creating it completely ? (just want to bring it to front)

Thanks !

Answer 1

On you subActivity onBackPressed() add this

@Override
public void onBackPressed() {
     Intent i = new Intent(SubActivity.this, MainActivity.class);
    i.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);

    startActivity(i);
}

on mainActivity :

  private void openSubActivity() {        

        Intent intent = new Intent(MainActivity.this,SubActivity.class);
       intent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
        startActivity(intent);

    }