How to show DatePickerDialog on Button click?

I. In your build.gradle add latest appcompat library, at the time 24.2.1

dependencies {  
    compile 'com.android.support:appcompat-v7:X.X.X' 
    // where X.X.X version
}

II. Make your activity extend android.support.v7.app.AppCompatActivity and implement the DatePickerDialog.OnDateSetListener interface.

public class MainActivity extends AppCompatActivity  
    implements DatePickerDialog.OnDateSetListener {

III. Create your DatePickerDialog setting a context, the implementation of the listener and the start year, month and day of the date picker.

DatePickerDialog datePickerDialog = new DatePickerDialog(  
    context, MainActivity.this, startYear, starthMonth, startDay);

IV. Show your dialog on the click event listener of your button

((Button) findViewById(R.id.myButton))
    .setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        datePickerDialog.show();
    }
});

it works for me. if you want to enable future time for choose, you have to delete maximum date. You need to to do like followings.

 btnDate.setOnClickListener(new View.OnClickListener() {
                       @Override
                       public void onClick(View v) {
                              DialogFragment newFragment = new DatePickerFragment();
                                    newFragment.show(getSupportFragmentManager(), "datePicker");
                            }
                        });

            public static class DatePickerFragment extends DialogFragment
                        implements DatePickerDialog.OnDateSetListener {

                    @Override
                    public Dialog onCreateDialog(Bundle savedInstanceState) {
                        final Calendar c = Calendar.getInstance();
                        int year = c.get(Calendar.YEAR);
                        int month = c.get(Calendar.MONTH);
                        int day = c.get(Calendar.DAY_OF_MONTH);
                        DatePickerDialog dialog = new DatePickerDialog(getActivity(), this, year, month, day);
                        dialog.getDatePicker().setMaxDate(c.getTimeInMillis());
                        return  dialog;
                    }

                    public void onDateSet(DatePicker view, int year, int month, int day) {
                       btnDate.setText(ConverterDate.ConvertDate(year, month + 1, day));
                    }
                }

    final Calendar newCalendar = Calendar.getInstance();
    final DatePickerDialog  StartTime = new DatePickerDialog(this, new DatePickerDialog.OnDateSetListener() {
                public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                    Calendar newDate = Calendar.getInstance();
                    newDate.set(year, monthOfYear, dayOfMonth);
                    activitydate.setText(dateFormatter.format(newDate.getTime()));
                }
    
            }, newCalendar.get(Calendar.YEAR), newCalendar.get(Calendar.MONTH), newCalendar.get(Calendar.DAY_OF_MONTH));
    
      btn_checkin.setOnClickListener(new View.OnClickListener() {
@Override   public void onClick(View v) {
         StartTime.show():    
     });