1.使用 Collections 工具类中的 sort() 方法

参数不同：

void sort(List list) 在自定义类User里面实现Comparable接口，并重写抽象方法compareTo(Student o);

void sort(List list, Comparator c) 第二个参数为了省事，可以直接使用匿名内部类

public class User implements Comparable{      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 users = new ArrayList();     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 = new ArrayList();     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() {        @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());     } }

2.直接使用list.sort()方法，传入实现Comparator接口的实现类的实例，为了省事直接传入匿名内部类

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 = new ArrayList();　　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() {　　　　@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());　　}}