Java List集合排序实现方法解析

public class User implements Comparable<User>{ 
   
  private int score; 
   
  private int age; 
   
  public User(int score, int age){ 
    super(); 
    this.score = score; 
    this.age = age; 
  } 
 
  public int getScore() { 
    return score; 
  } 
 
  public void setScore(int score) { 
    this.score = score; 
  } 
 
  public int getAge() { 
    return age; 
  } 
 
  public void setAge(int age) { 
    this.age = age; 
  } 
 
  @Override 
  public int compareTo(User o) { 
    int i = this.getAge() - o.getAge();//先按照年龄排序 
    if(i == 0){ 
      return this.score - o.getScore();//如果年龄相等了再用分数进行排序 
    } 
    return i; 
  } 
   
} 
 
public static void main(String[] args) { 
    List<User> users = new ArrayList<User>(); 
    users.add(new User(78, 26)); 
    users.add(new User(67, 23)); 
    users.add(new User(34, 56)); 
    users.add(new User(55, 23)); 
    Collections.sort(users); 
    for(User user : users){ 
      System.out.println(user.getScore() + "," + user.getAge()); 
    } 
}

public class Students { 
   
  private int age; 
  private int score; 
   
  public Students(int age, int score){ 
    super(); 
    this.age = age; 
    this.score = score; 
  } 
   
  public int getAge() { 
    return age; 
  } 
  public void setAge(int age) { 
    this.age = age; 
  } 
  public int getScore() { 
    return score; 
  } 
  public void setScore(int score) { 
    this.score = score; 
  } 
} 
public static void main(String[] args) { 
    List<Students> students = new ArrayList<Students>(); 
    students.add(new Students(23, 100)); 
    students.add(new Students(27, 98)); 
    students.add(new Students(29, 99)); 
    students.add(new Students(29, 98)); 
    students.add(new Students(22, 89)); 
    Collections.sort(students, new Comparator<Students>() { 
 
      @Override 
      public int compare(Students o1, Students o2) { 
        int i = o1.getScore() - o2.getScore(); 
        if(i == 0){ 
          return o1.getAge() - o2.getAge(); 
        } 
        return i; 
      } 
    }); 
    for(Students stu : students){ 
      System.out.println("score:" + stu.getScore() + ":age" + stu.getAge()); 
    } 
}

public class Students {

  private int age;
  private int score;

  public Students(int age, int score){
    this.age = age;
    this.score = score;
  }

  public int getAge() {
    return age;
  }
  public void setAge(int age) {
    this.age = age;
  }
  public int getScore() {
    return score;
  }
  public void setScore(int score) {
    this.score = score;
  }
}
public static void main(String[] args) {
　　List<Students> students = new ArrayList<Students>();
　　students.add(new Students(23, 100));
　　students.add(new Students(27, 98));
　　students.add(new Students(29, 99));
　　students.add(new Students(29, 98));
　　students.add(new Students(22, 89));

　　students.sort(new Comparator<Students>() {
　　　　@Override
　　　　public int compare(Students o1, Students o2) {
　　　　　　int i = o1.getScore() - o2.getScore();
　　　　　　if (i == 0) {
　　　　　　　　return o1.getAge() - o2.getAge();
　　　　　　}
　　　　　　return i;
　　　　}
　　});

　　for (Students stu : students) {
　　　　System.out.println("score:" + stu.getScore() + ":age" + stu.getAge());
　　}
}