对象集合，按照指定的字段排序

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class Demo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        List<String> names = Arrays.asList("peter", "anna", "mike", "xenia");        
        Collections.sort(names, new Comparator<String>() {
            @Override
            public int compare(String a, String b) {
                return b.compareTo(a);
            }
        });
        System.out.println(names);
        
        List<Person> listPerson=new ArrayList<>();
        listPerson.add(new Person(1,"Ivan",26));
        listPerson.add(new Person(2,"Tom",24));
        listPerson.add(new Person(3,"Jake",18));
        listPerson.add(new Person(3,"King",28));
        Person.SortByAge(listPerson);
        for(Person p:listPerson){
            System.out.println(p.name+":"+p.age);
        }
    }

}

class Person{
    int id;
     String name;
    int age;
    public Person (int id,String name,int age){
        this.id=id;
        this.name=name;
        this.age=age;
    }
    public static void SortByAge(List<Person> listPerson){
        Collections.sort(listPerson,new Comparator<Person>(){
            @Override
            public int compare(Person o1, Person o2) {
                int age1=o1.age;
                int age2=o2.age;
                if(age1>age2)
                    return 0;
                else if(age1<age2)
                    return -1;
                else 
                    return 0;    
                 
            }
            
        });
        
    }
    
}