public class MainActivity extends AppCompatActivity {

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

        final TextView tv = findViewById(R.id.textView);

        findViewById(R.id.btn_who).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                PopupMenu popup = new PopupMenu(MainActivity.this, findViewById(R.id.btn_who));
                popup.getMenuInflater().inflate(R.menu.menu_pop, popup.getMenu());
                popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    @SuppressLint("SetTextI18n")
                    @Override
                    public boolean onMenuItemClick(MenuItem item) {
                        switch (item.getItemId()){
                            case R.id.monika:
                                tv.setText("Sure, just Monika");
                                break;
                            case R.id.sayori:
                            case R.id.natsuki:
                            case R.id.yuri:
                                tv.setText("Oh god, you selected  " + item.getTitle() + " . But you should know\nJUST MONIKA, right?");
                                break;
                            case R.id.delete:
                                tv.setText("Wait...What? You mean you don't need Monika anymore?");
                                break;
                        }
                        return true;
                    }
                });
                popup.show();
            }
        });
    }
}