Timepicker with 15 minute intervals

Question

I have a custom dialog with a timepicker and a datepicker. I want to set the timepicker's minute spinner collection to [0, 15, 30, 45] ie 15 min intervals.

Now i see several solutions but none seem to cover the fact that the UI will show the next and previous minutes as -1 and +1 minutes of selected minute eg 29, 30, 31 are shown to user.

Also, im not clear on how i attach my custom timepicker to an activity - do i not need a customerTimePicker xml component to do this?

So in short - do i adjust the native timepicker or need to build a custom xml and class?

What i have at present Layout:

<TimePicker
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/timePicker_fixture"
    android:layout_weight="1" />

Activity

TimePicker timePicker_fixture = (TimePicker) dialog.findViewById(R.id.timePicker_fixture);
timePicker_fixture.setIs24HourView(true);

A suggested custom class (how do i use this - do i need a custom xml component in my layout?)

public class CustomTimePickerDialog extends TimePickerDialog {

    private final static int TIME_PICKER_INTERVAL = 15;
    private TimePicker timePicker;
    private final OnTimeSetListener callback;

    public CustomTimePickerDialog(Context context, OnTimeSetListener callBack,
                                  int hourOfDay, int minute, boolean is24HourView) {
        super(context, TimePickerDialog.THEME_HOLO_LIGHT, callBack, hourOfDay, minute / TIME_PICKER_INTERVAL,
                is24HourView);
        this.callback = callBack;
    }

    @Override
    public void onClick(DialogInterface dialog, int which) {
        if (callback != null && timePicker != null) {
            timePicker.clearFocus();
            callback.onTimeSet(timePicker, timePicker.getCurrentHour(),
                    timePicker.getCurrentMinute() * TIME_PICKER_INTERVAL);
        }
    }

    @Override
    protected void onStop() {
    }

    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        try {
            Class<?> classForid = Class.forName("com.android.internal.R$id");
            Field timePickerField = classForid.getField("timePicker");
            this.timePicker = (TimePicker) findViewById(timePickerField
                    .getInt(null));
            Field field = classForid.getField("minute");

            NumberPicker mMinuteSpinner = (NumberPicker) timePicker
                    .findViewById(field.getInt(null));
            mMinuteSpinner.setMinValue(0);
            mMinuteSpinner.setMaxValue((60 / TIME_PICKER_INTERVAL) - 1);
            List<String> displayedValues = new ArrayList<String>();
            for (int i = 0; i < 60; i += TIME_PICKER_INTERVAL) {
                displayedValues.add(String.format("%02d", i));
            }
            mMinuteSpinner.setDisplayedValues(displayedValues
                    .toArray(new String[0]));
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

Answer 1

Added the following

   @SuppressLint("NewApi")
    private void setTimePickerInterval(TimePicker timePicker) {
        try {
            Class<?> classForid = Class.forName("com.android.internal.R$id");
            // Field timePickerField = classForid.getField("timePicker");

            Field field = classForid.getField("minute");
            minutePicker = (NumberPicker) timePicker
                    .findViewById(field.getInt(null));

            minutePicker.setMinValue(0);
            minutePicker.setMaxValue(7);
            displayedValues = new ArrayList<String>();
            for (int i = 0; i < 60; i += TIME_PICKER_INTERVAL) {
                displayedValues.add(String.format("%02d", i));
            }
            for (int i = 0; i < 60; i += TIME_PICKER_INTERVAL) {
                displayedValues.add(String.format("%02d", i));
            }
            minutePicker.setDisplayedValues(displayedValues
                    .toArray(new String[0]));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

in my activity and then called this method from oncreate(). Of course you can call it from wherever necessary.