Android Material Design Popup Menu

main_activity.java

@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();
        if (id == R.id.item1_id) {
            Toast.makeText(getApplicationContext(), "Item 1 is selected", Toast.LENGTH_SHORT).show();
        } else if (id == R.id.item2_id) {
            Toast.makeText(getApplicationContext(), "Item 2 is selected", Toast.LENGTH_SHORT).show();
        } else if (id == R.id.item3_id) {
            Toast.makeText(getApplicationContext(), "Item 3 is selected", Toast.LENGTH_SHORT).show();
        }
        return super.onOptionsItemSelected(item);
    }