TreeSet课后习题

TreeSet课后习题

package com.atguigu.exer1;

import org.junit.Test;

import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;

/**
 * 创建该类的5个对象，并把这些对象放入TreeSet集合中，分别按一下两种方式对集合中的元素进行排序。并遍历输出
 * <p>
 * 1.使Employee实现Comparable接口，并按name排序
 * 2.创建TreeSet时传入Comparator对象，按生日日期的先后排序
 *
 * @author liangqichen
 * @create 2021-09-28 21:27
 */
public class EmployeeTest {

    // 问题2 按生日日期的先后顺序
    @Test
    public void test2() {

        TreeSet set = new TreeSet(new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                if(o1 instanceof Employee && o2 instanceof Employee) {
                    Employee e1 = (Employee) o1;
                    Employee e2 = (Employee) o2;
                    MyDate b1 = e1.getBirthday();
                    MyDate b2 = e2.getBirthday();

                    // 方式 一
//                    // 比较年
//                    int minusYear = b1.getYear() - b2.getYear();
//                    if(minusYear != 0){
//                        return minusYear;
//                    }
//
//                    // 比较月
//                    int minMonth = b1.getMonth() - b2.getMonth();
//                    if(minMonth != 0){
//                        return minMonth;
//                    }
//
//                    // 比较日
//                    return b1.getDay() - b2.getDay();
//                }
                    // 方式 二 ：
                    return b1.compareTo(b2);
                }
                return 0;
            }
        });
        Employee e1 = new Employee("liudehua", 55, new MyDate(1965, 5, 4));
        Employee e2 = new Employee("zhangxueyou", 43, new MyDate(1987, 5, 4));
        Employee e3 = new Employee("guofucheng", 44, new MyDate(1987, 5, 9));
        Employee e4 = new Employee("liming", 51, new MyDate(1954, 8, 12));
        Employee e5 = new Employee("liangchaowei", 21, new MyDate(1958, 12, 4));

        set.add(e1);
        set.add(e2);
        set.add(e3);
        set.add(e4);
        set.add(e5);

        Iterator iterator = set.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }


    // 问题1 使用自然排序
    @Test
    public void test1() {
        TreeSet set = new TreeSet();
        Employee e1 = new Employee("liudehua", 55, new MyDate(1965, 5, 4));
        Employee e2 = new Employee("zhangxueyou", 43, new MyDate(1987, 5, 4));
        Employee e3 = new Employee("guofucheng", 44, new MyDate(1987, 5, 9));
        Employee e4 = new Employee("liming", 51, new MyDate(1954, 8, 12));
        Employee e5 = new Employee("liangchaowei", 21, new MyDate(1958, 12, 4));

        set.add(e1);
        set.add(e2);
        set.add(e3);
        set.add(e4);
        set.add(e5);

        Iterator iterator = set.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

    }
}

package com.atguigu.exer1;

/**
 * 定义一个Employee类。
 * 该类包含：private成员变量name，age，birthday，其中birthday 为MayDate类的对象：
 * 并为每一个属性定义getter setter方法
 * 并重写toString方法输出name  age  birthday
 *
 * @author liangqichen
 * @create 2021-09-28 21:23
 */
public class Employee  implements Comparable{
    private String name;
    private int age;
    private MyDate birthday;

    public Employee() {
    }

    public Employee(String name, int age, MyDate birthday) {
        this.name = name;
        this.age = age;
        this.birthday = birthday;
    }

    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 MyDate getBirthday() {
        return birthday;
    }

    public void setBirthday(MyDate birthday) {
        this.birthday = birthday;
    }

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

    // 按照 name 的顺序排
    @Override
    public int compareTo(Object o) {
        if(o instanceof Employee){
            Employee e = (Employee) o;
            return this.name.compareTo(e.name);
        }
//        return 0;
        throw new RuntimeException("传入的数据类型不一致！");
    }
}

package com.atguigu.exer1;

/**
 * MyDate类包含：
 * private成员变量year，month，day。并为每一个属性定义getter setter 方法。
 *
 * @author liangqichen
 * @create 2021-09-28 21:20
 */
public class MyDate implements Comparable{
    private int year;
    private int month;
    private int day;

    public MyDate() {
    }

    public MyDate(int year, int month, int day) {
        this.year = year;
        this.month = month;
        this.day = day;
    }

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }

    public int getMonth() {
        return month;
    }

    public void setMonth(int month) {
        this.month = month;
    }

    public int getDay() {
        return day;
    }

    public void setDay(int day) {
        this.day = day;
    }

    @Override
    public String toString() {
        return "MyDate{" +
                "year=" + year +
                ", month=" + month +
                ", day=" + day +
                '}';
    }



    @Override
    public int compareTo(Object o) {
        if (o instanceof MyDate) {
            MyDate m = (MyDate) o;

            // 比较年
            int minusYear = this.getYear() - m.getYear();
            if (minusYear != 0) {
                return minusYear;
            }

            // 比较月
            int minMonth = this.getMonth() - m.getMonth();
            if (minMonth != 0) {
                return minMonth;
            }

            // 比较日
            return this.getDay() - m.getDay();
        }
        throw new RuntimeException("传入的数据类型不一致！！");
    }
}

标签：return,int,MyDate,课后,Employee,new,习题,public,TreeSet
来源： https://blog.csdn.net/weixin_56711112/article/details/120539345