Answers for "bottom navigation item switch item android"

android up navigation

@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
  int itemId = item.getItemId();
  if (itemId == android.R.id.home) {
    // force up navigation to have the same behavior as temporal navigation
    onBackPressed();
    return true;
  } else {
    return super.onOptionsItemSelected(item);
  }
}

android bottomnavigationview set current item

BottomNavigationView bottomNavigationView;
bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottomNavigationView);
bottomNavigationView.setOnNavigationItemSelectedListener(myNavigationItemListener);
bottomNavigationView.setSelectedItemId(R.id.my_menu_item_id);