java如何对ArrayList中对象按照该对象某属性排序

有几个方法可以实现：让
Student 实现Comparable接口，或是实例化一个比较器，现在用 Comparator 比较器实例来做一个：ComparableTest.java

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

public class ComparableTest {

public static void main(String[] args) {

Comparator<Student> comparator = new Comparator<Student>(){

public int compare(Student s1, Student s2) {

//先排年龄

if(s1.age!=s2.age){

return s2.age-s1.age;

}

else{

//年龄相同则按姓名排序

if(!s1.name.equals(s2.name)){

return s2.name.compareTo(s1.name);

}

else{

//姓名也相同则按学号排序

return s2.id-s1.id;

}

}

}

};

Student stu1 = new Student (1,"zhangsan","male",28,"cs");

Student stu2 = new Student (2,"lisi","female",19,"cs");

Student stu3 = new Student (3,"wangwu","male",22,"cs");

Student stu4 = new Student (4,"zhaoliu","female",17,"cs");

Student stu5 = new Student (5,"jiaoming","male",22,"cs");

ArrayList<Student> List = new ArrayList<Student>();

List.add(stu1);

List.add(stu2);

List.add(stu3);

List.add(stu4);

List.add(stu5);

//这里就会自动根据规则进行排序

Collections.sort(List,comparator);

display(List);

}

static void display(ArrayList<Student> lst){

for(Student s:lst)

System.out.println(s);

}

}

class Student{

int age;

int id;

String gender;

String name;

String cs;

Student(int id,String name,String gender,int age,String cs){

this.age=age;

this.name=name;

this.gender=gender;

this.id=id;

this.cs=cs;

}

public String toString(){

return id+" "+name+" "+gender+" "+age+" "+cs;

}

}

2.添加 Comparable 接口，重写 compareTo 方法。然后你可以用 TreeSet 结构进行排序。它会自动排序。

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