The preference showing a dialog with a time picker. Supports disabled state.

TimePreference.java

/**
 * Based on http://stackoverflow.com/a/10608622/2489474
 * <p>Created by Maksim Kovalev on 05.04.2017.
 */
public class TimePreference extends DialogPreference {

    public static final long TIME_NOT_SET = -1;

    private TimePicker picker = null;

    private long time = TIME_NOT_SET;

    public TimePreference(Context context) {
        this(context, null);
    }

    public TimePreference(Context context, AttributeSet attrs) {
        this(context, attrs, android.R.attr.dialogPreferenceStyle);
    }

    public TimePreference(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        setPositiveButtonText(android.R.string.ok);
        setNegativeButtonText(android.R.string.cancel);
    }

    @Override
    protected void onPrepareDialogBuilder(AlertDialog.Builder builder) {
        builder.setNeutralButton(R.string.reset, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                time = TIME_NOT_SET;
                notifyTimeChanged();
            }
        });
    }

    @Override
    protected View onCreateDialogView() {
        Context context = getContext();
        picker = new TimePicker(context);
        picker.setIs24HourView(DateFormat.is24HourFormat(context));
        return picker;
    }

    @Override
    @SuppressWarnings("deprecation")
    protected void onBindDialogView(View v) {
        super.onBindDialogView(v);

        Calendar calendar = Calendar.getInstance();
        if (time != TIME_NOT_SET) {
            calendar.setTimeInMillis(time);
        }

        picker.setCurrentHour(calendar.get(Calendar.HOUR_OF_DAY));
        picker.setCurrentMinute(calendar.get(Calendar.MINUTE));
    }

    @Override
    @SuppressWarnings("deprecation")
    protected void onDialogClosed(boolean positiveResult) {
        if (!positiveResult) {
            return;
        }

        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.HOUR_OF_DAY, picker.getCurrentHour());
        calendar.set(Calendar.MINUTE, picker.getCurrentMinute());
        time = calendar.getTimeInMillis();

        notifyTimeChanged();
    }

    @Override
    protected Object onGetDefaultValue(TypedArray a, int index) {
        return a.getString(index);
    }

    @Override
    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
        if (restoreValue) {
            if (defaultValue == null) {
                time = getPersistedLong(TIME_NOT_SET);
            } else {
                time = Long.parseLong(getPersistedString((String) defaultValue));
            }
        } else {
            if (defaultValue == null) {
                time = TIME_NOT_SET;
            } else {
                time = Long.parseLong((String) defaultValue);
            }
        }

        persistLong(time);
        updateSummary();
    }

    @Override
    public CharSequence getSummary() {
        if (time == TIME_NOT_SET) {
            return getContext().getString(R.string.disabled);
        } else {
            java.text.DateFormat format = DateFormat.getTimeFormat(getContext());
            return format.format(new Date(time));
        }
    }

    private void updateSummary() {
        setSummary(getSummary());
    }

    private void notifyTimeChanged() {
        updateSummary();
        if (callChangeListener(time)) {
            persistLong(time);
            notifyChanged();
        }
    }
}