How to create dialog series 1 basic - java 3

MainActivity.java

public class MainActivity extends AppCompatActivity {

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

        findViewById(R.id.btn).setOnClickListener(view -> {
            DialogFragment dialogFragment = new MyDialogFragment();
            dialogFragment.show(getSupportFragmentManager(), "my_dialog");
        });
    }
}