DateTimePicker Dialog

date_time_picker.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:padding="8dp"
    android:layout_height="match_parent">

    <DatePicker
        android:id="@+id/date_picker"
        android:layout_width="match_parent"
        android:calendarViewShown="true"
        android:spinnersShown="false"
        
        <!-- These will show spinners instead of calendar
        android:calendarViewShown="false"
        android:datePickerMode="spinner" 
        -->
        
        android:layout_weight="4"
        android:layout_height="0dp" />

    <TimePicker
        android:id="@+id/time_picker"
        android:layout_weight="4"
        android:layout_width="match_parent"
        <!-- This will show a spinner
        android:timePickerMode="spinner"
        -->
        android:layout_height="0dp" />

    <Button
        android:id="@+id/date_time_set"
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:text="Set"
        android:layout_height="0dp" />

</LinearLayout>

ShowDate.java

    private void shodDateDialog() {
        final View dialogView = View.inflate(this, R.layout.date_time_picker, null);
        final AlertDialog alertDialog = new AlertDialog.Builder(this).create();

        /* This will set up the default values */
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(mDate);

        DatePicker datePicker = (DatePicker) dialogView.findViewById(R.id.date_picker);
        TimePicker timePicker = (TimePicker) dialogView.findViewById(R.id.time_picker);

        datePicker.updateDate(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
        timePicker.setCurrentHour(calendar.get(Calendar.HOUR_OF_DAY));
        timePicker.setCurrentMinute(calendar.get(Calendar.MINUTE));
        
        /* This will correctly choose the format coherent with the locale - AM/PM or 24Hrs */
        timePicker.setIs24HourView(android.text.format.DateFormat.is24HourFormat(this));
        

        dialogView.findViewById(R.id.date_time_set).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                DatePicker datePicker = (DatePicker) dialogView.findViewById(R.id.date_picker);
                TimePicker timePicker = (TimePicker) dialogView.findViewById(R.id.time_picker);

                Calendar calendar = Calendar.getInstance();
                calendar.set(datePicker.getYear(),
                        datePicker.getMonth(),
                        datePicker.getDayOfMonth(),
                        timePicker.getCurrentHour(),
                        timePicker.getCurrentMinute());

                mDate.setTime(calendar.getTimeInMillis());
                alertDialog.dismiss();
                dateChanged();
            }});
        alertDialog.setView(dialogView);
        alertDialog.show();
    }