java开发jdk1.7下List集合中按照对象中指定字段排序，List集合中按照map中指定字段排序

目录

jdk1.7List集合中按照对象中指定字段排序

jdk1.7List集合中按照map中指定字段排序

jdk1.7List集合中按照对象中指定字段排序

题目：现在有一个list集合、里面存放着多个Student对象，现要求按照Student的score进行排序

代码演示：

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

public class Student {
    public Student(String name, int score) {
        this.name = name;
        this.score = score;
    }

    private String name;
    private int score;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }
    public static void main(String[] args) {
        Student student = new Student("张三",60);
        Student student2 = new Student("李四",30);
        Student student3 = new Student("王五",80);
        Student student4 = new Student("赵六",90);
        List studentList = new ArrayList<>();
        studentList.add(student);
        studentList.add(student2);
        studentList.add(student3);
        studentList.add(student4);
        System.out.println("排序前");
        for (Student o : studentList) {
            System.out.println(o.getName()+"  "+o.getScore());
        }
        Collections.sort(studentList, new Comparator() {
            @Override
            public int compare(Student o1, Student o2) {
                //排序字段   正序    如果需要倒序则将两个值调换
                return o1.getScore()-o2.getScore();   
            }
        });
          

        System.out.println("排序后");
        for (Student o : studentList) {
            System.out.println(o.getName()+"  "+o.getScore());
        }

    }
}

结果输出：

jdk1.7List集合中按照map中指定字段排序

题目：现在有一个list集合、里面存放着多个Map，Map中用于存储学生的姓名，语文成绩、数学成绩、英语成绩，现在需要按照语文成绩进行排序输出

代码演示：

import java.util.*;

public class Student {
    public static void main(String[] args) {
       List

结果输出：