FAB on click start new activity based on fragment currently shown

Question

I am trying to figure a good way to start an activity from a click on the floating action button. My FAB is located in mainactivity.xml. My MainActivity consists of bottom navigation with fragments. I need to implement a different on click action determined by a fragment that is shown.

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab_add);
fab.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
    fabClicked();
    }
});

fabClicked Method

public void fabClicked() {
    Object id = getSupportFragmentManager().findFragmentById(R.id.container);


    if ((getSupportFragmentManager().findFragmentById(R.id.fragment_1)).equals(id)) {
        Intent intent1 = new Intent(MainActivity.this, Add1.class);
        startActivity(intent1);
    }

    else if ((getSupportFragmentManager().findFragmentById(R.id.fragment_2)).equals(id)) {
        Intent intent2 = new Intent(MainActivity.this, Add2.class);
        startActivity(intent2);
    }

    else if ((getSupportFragmentManager().findFragmentById(R.id.fragment_3)).equals(id)) {
        Intent intent3 = new Intent(MainActivity.this, Add3.class);
        startActivity(intent3);
    }
    else if ((getSupportFragmentManager().findFragmentById(R.id.fragment_home)).equals(id)) {
        //plan to add to code to hide fab on homescreen
    }

}

Answer 1

Your approach is good, but it's doing many unnecessary expensive Fragment lookups.

You can get the navigation id of the current Fragment with:

navController.getCurrentDestination().getId()

You can then use this returned id to do different things in the click listener based on the Fragment, like so:

fun fabClicked() {
    val id = navController.getCurrentDestination().getId()
    val class = when(id) {
        R.id.fragment_1 -> Add1::class
        R.id.fragment_2 -> Add2::class
        // etc
    }
    startActivity(Intent(this, class.javaClass))
}

In this way, you don't need to do Fragment look-ups for each condition, just simply compare ids. You can also extract the shared startActivity logic (as shown here) to make this much more concise.