Java比较器实现方法项目案例

public class Entity implements Comparable<Entity> {
  @Override
  public int compareTo(Entity o) {
    return 0;
  }
}

public class EntityComparator implements Comparator<Entity> {
  @Override
  public int compare(Entity o1, Entity o2) {
    return 0;
  }
}

public class Record {
  //状态
  private String state;
  //时长
  private String time;
  public Record(String state, String time) {
    this.state = state;
    this.time = time;
  }
  public String getState() {
    return state;
  }
  public String getTime() {
    return time;
  }
  @Override
  public String toString() {
    return "Record{" +
        "state='" + state + '\'' +
        ", time='" + time + '\'' +
        '}';
  }
}

public class RecordComparator implements Comparator<Record> {
  @Override
  public int compare(Record o1, Record o2) {
    final int stateCompare = o1.getState().compareTo(o2.getState());
    if (stateCompare == 0) {
      return o1.getTime().compareTo(o2.getTime());
    }
    return stateCompare;
  }
}

public class RecordTimeDescComparator implements Comparator<Record> {
  @Override
  public int compare(Record o1, Record o2) {
    final int stateCompare = o1.getState().compareTo(o2.getState());
    if (stateCompare == 0) {
      return o2.getTime().compareTo(o1.getTime());
    }
    return stateCompare;
  }
}

Record record1 = new Record("通话中", "00:01:08");
Record record2 = new Record("空闲", "00:18:02");
Record record3 = new Record("通话中", "00:04:04");
Record record4 = new Record("空闲", "00:01:57");
List<Record> recordList = new ArrayList<>();
recordList.add(record1);
recordList.add(record2);
recordList.add(record3);
recordList.add(record4);
System.out.println("排序前：" + recordList);
Collections.sort(recordList, new RecordComparator());
System.out.println("排序后【时间正序】：" + recordList);
recordList = new ArrayList<>();
recordList.add(record1);
recordList.add(record2);
recordList.add(record3);
recordList.add(record4);
System.out.println("排序前：" + recordList);
Collections.sort(recordList, new RecordTimeDescComparator());
System.out.println("排序后【时间倒序】：" + recordList);