private TextView mTextMessage;

private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.navigation_home:
                mTextMessage.setText(R.string.title_home);
                Intent i = new Intent(display.this, Addab.class);
                startActivity(i);
                break;

            case R.id.navigation_dashboard:
                mTextMessage.setText(R.string.title_dashboard);
                break;
            case R.id.navigation_notifications:
                mTextMessage.setText(R.string.title_notifications);
                break;
        }

        return false;
    }
};

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display);

    mTextMessage = (TextView) findViewById(R.id.message);
    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

}