public class MainActivity extends AppCompatActivity implements TimePickerDialog.OnTimeSetListener {

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

        Button button_start = (Button) findViewById(R.id.start_picker_button);
        button_start.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                DialogFragment timePicker1 = new TimePickerStartFragment();
                timePicker1.show(getSupportFragmentManager(),"time picker start");
            }
        });

        Button button_end = (Button) findViewById(R.id.end_picker_button);
        button_end.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                DialogFragment timePicker2 = new TimePickerEndFragment();
                timePicker2.show(getSupportFragmentManager(),"time picker end");
            }
        });

    }

    @Override
    public void onTimeSet(TimePicker TimePickerStartFragment, int hourOfDay, int minute) {
        TextView textView = (TextView)findViewById(R.id.textView);
        textView.setText("Hour: " + hourOfDay + " " + "Minute: " + minute);