应用程序返回按两次退出-不能正常工作

Question

I have a bit of a weird one that I can't quite figure out.

When I log out of my app via the navigation menu, it takes me back to the login screen. I have then set it up so that when the user presses the back button twice, it should close the app completely. I have got the toast to appear after one press to say the user needs to press twice but here's my issue.

When I press back twice, the screen clears but the login screen pops back up again. With my last login details in the boxes. Then if I press back twice again, it closes the app completely. I need to try and figure out why it won't close the app on the first two presses of the back button.

Below is the code I am using:

public void onBackPressed() {
    //moveTaskToBack(true);
    if (!isUserClickedBackButton){
        Toast.makeText(this, "Press back again to exit", Toast.LENGTH_SHORT).show();
        isUserClickedBackButton = true;
    } else {
        System.exit(0); // exits right out of app
        super.onBackPressed();

    }
}

I have tried not using 'super.onBackPressed', I've tried using it on its own. I've tried adding 'finish()' or just using that on its own. I'm at a loss. Has anyone got any ideas?

I'm using Firebase for authentication if that makes any difference.

Thanks in advance.

Answer 1

You can use:

super.onBackPressed();

And add in the AndroidManifest.xml to the login activity tag:

android:noHistory="true"

Answer 2

You Can do it without using no History in android manifest if you want...

//Use this as class variable..
boolean doublePressedBackExit = false;   


@Override
public void onBackPressed() {
    if (doublePressedBackExit) {
        Intent intent = new Intent(Intent.ACTION_MAIN);
        intent.addCategory(Intent.CATEGORY_HOME);
        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent);
        finish();
        System.exit(0);
        return;
    }
    this.doublePressedBackExit = true;
    Toast.makeText(getApplicationContext(), "Press again to exit..", Toast.LENGTH_SHORT).show();
    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {
            doublePressedBackExit = false;
        }
    }, 2000);
}