Determine backstack fragment empty state in android

Question

My application structure look like:

  SplashActivity -> MainActivity -> (switching between many fragments)

What I expect: finish application from main activity when fragment back stack count is zero. Here is my try:

In SplashAcitivty

  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getIntent().getBooleanExtra("exit", false)) {
        finish();
    }
  }

In MainActivity:

@Override
public void onBackPressed() {
  // I need to implement this method
  if( backstackCount() == 0){
    Intent intent = new Intent(this, SplashActivity.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    intent.putExtra(SplashActivity.EXIT_KEY, true);
    startActivity(intent);
   }else{
    super.onBackPressed();
   }
}

So, please tell me how can I determine the back stack when it 's empty? Because I use SlideMenu library, all of my fragments switch many times, and they are added to back stack when switching. Look like this one:

 getSupportFragmentManager()
    .beginTransaction()
    .replace(R.id.content_frame, fragment)
    .addToBackStack(null)
    .commit();

Answer 1

Here is my code. It works fine for me:

@Override
public void onBackPressed() {

    int backStackEntryCount = getSupportFragmentManager().getBackStackEntryCount();
    if (backStackEntryCount == 0) {
        goBack();   // write your code to switch between fragments.
    } else {
        super.onBackPressed();
    }
}