Сортировка объектов по времени

import android.support.annotation.NonNull;
 
import java.util.ArrayList;
import java.util.List;
 
public class ProgramItem implements Comparable<ProgramItem> {
    public final int hours;
    public final int minutes;
 
    public ProgramItem(@NonNull String time) {
        String[] times = time.split(":");
        this.hours = Integer.parseInt(times[0]);
        this.minutes = Integer.parseInt(times[1]);
    }
 
    @NonNull
    public static List<ProgramItem> parseCollection(@NonNull String[] stringTimes) {
        List<ProgramItem> items = new ArrayList<>();
        for (String timeItem : stringTimes) {
            items.add(new ProgramItem(timeItem));
        }
        return items;
    }
 
    @Override
    public String toString() {
        String hourStr = hours < 10 ? "0" + hours : String.valueOf(hours);
        String minStr = minutes < 10 ? "0" + minutes : String.valueOf(minutes);
        return hourStr + ":" + minStr;
    }
 
    @Override
    public int compareTo(@NonNull ProgramItem o) {
        int t1 = hours * 60 + minutes;
        int t2 = o.hours * 60 + o.minutes;
        return t1 == t2 ? 0 : t1 > t2 ? 1 : -1;
    }
}

import org.junit.Test;
 
import java.util.Collections;
import java.util.List;
 
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;
 
public class ProgramItemTest {
 
    @Test
    public void test_constructor() throws Exception {
        ProgramItem first = new ProgramItem("00:00");
        assertThat(first.hours, is(0));
        assertThat(first.minutes, is(0));
 
        ProgramItem second = new ProgramItem("09:01");
        assertThat(second.hours, is(9));
        assertThat(second.minutes, is(1));
 
        ProgramItem third = new ProgramItem("23:59");
        assertThat(third.hours, is(23));
        assertThat(third.minutes, is(59));
    }
 
    @Test
    public void compareTo_oneMinuteTop() throws Exception {
        ProgramItem first = new ProgramItem("00:00");
        ProgramItem second = new ProgramItem("00:01");
        int compare = first.compareTo(second);
        assertThat(compare, is(-1));
    }
 
    @Test
    public void compareTo_oneDayTop() throws Exception {
        ProgramItem first = new ProgramItem("00:00");
        ProgramItem second = new ProgramItem("23:59");
        int compare = first.compareTo(second);
        assertThat(compare, is(-1));
    }
 
    @Test
    public void test_collection_sort() throws Exception {
        String[] input = new String[]{"02:00", "09:00", "01:00", "15:00", "21:00", "00:00", "23:00"};
        String[] expected = new String[]{"00:00", "01:00", "02:00", "09:00", "15:00", "21:00", "23:00"};
 
        List<ProgramItem> times = ProgramItem.parseCollection(input);
        Collections.sort(times);
        String[] actual = new String[times.size()];
        for (int i = 0; i < times.size(); i++) {
            actual[i] = times.get(i).toString();
        }
        assertThat(actual, is(expected));
 
    }
}