经典笔试题：有一个学生集合要求按照学生的身高从低到高排序（根据Collections.sort重载方法来实现）

package com.gaopeng.interview;

public class Student {

    private String name;

    private int age;

    private int height;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", height=" + height +
                '}';
    }
}

package com.gaopeng.interview;

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

public class SortStudentByHeight {

    public static void main(String[] args) {

        Student s1 = new Student();
        s1.setName("张三");
        s1.setAge(18);
        s1.setHeight(185);

        Student s2 = new Student();
        s2.setName("李四");
        s2.setAge(15);
        s2.setHeight(172);

        Student s3 = new Student();
        s3.setName("王五");
        s3.setAge(22);
        s3.setHeight(179);

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

        studentList.add(s1);
        studentList.add(s2);
        studentList.add(s3);

        Collections.sort(studentList, new Comparator<Student>() {


            /**
             *对象比较大小方法，返回负整数、零或正整数(并没有一定要返回-1，0，1)，
             * 根据此对象是小于、等于还是大于指定对象。
             * 返回值的含义如下：
             * 1：对象1大于对象2
             * 0：两个对象相等
             *-1：对象1小于对象2
             */
            @Override
            public int compare(Student s1, Student s2) {

                int h1 = s1.getHeight();
                int h2 = s2.getHeight();

                if (h1 > h2) {
                    return 1;
                } else if (h1 == h2) {
                    return 0;
                } else {
                    return -1;
                }
            }
        });

        System.out.println(studentList);

    }
}

运行结果如下：

[Student{name='李四', age=15, height=172}, Student{name='王五', age=22, height=179}, Student{name='张三', age=18, height=185}]