JAVA排序

 List<People> list = ...; //import java.util.ArrayList;

import java.util.Collections;
import java.util.List;

class Person implements Comparable{
    private int  age;
    private String name;
    
    public Person() {
        // TODO Auto-generated constructor stub
        age=0;
        name="";
    }
    Person(int age,String name){
        this.age = age;
        this.name =name;
    }
    public String getName() {
        return name;
    }
    public int getAge() {
        return age;
    }
    @Override
    public int compareTo(Object o) {
        // TODO Auto-generated method stub
        Person p = (Person)o;
        if(this.name.compareTo(p.getName())>0){
            return 1;
        }
        else if(this.name.compareTo(p.getName())<0){
            return -1;
        }
        else{
            if(this.age>p.getAge()){
                return 1;
            }
            else if(this.age<p.getAge()){
                return -1;
            }
        }
            
        return 0;
    }
    
    
}

public class TestSort {
    public static void main(String[] args) {
        List<Person> list = new ArrayList<Person>() ;
        list.add(new Person(31,"zhangsan"));
        list.add(new Person(13,"lisi"));
        list.add(new Person(24,"wangwu"));
        list.add(new Person(24,"lisi"));
        
        Collections.sort(list);
        
        for (Object o : list) {
            Person p = (Person)o;
            System.out.println(p.getName()+" "+p.getAge());
        }
    }

}有个保存了People类的List

Collections.sort(list, new Comparator<People>() { //排序
    public int compare(People p1, People p2) {
        if (p1.getName().compareTo(p2.getName()) == 0) { //如果名字相同
            return p2.getAge() - p1.getAge(); //年龄降序
        }
        return p1.getName().compareTo(p2.getName()); //姓名升序
    }
});
//这样list就排序好了，上述假设People类有getName方法获取姓名，getAge方法获取年龄