HashSet练习

HashSet练习

下图为重写equals方法的位置,alt+insert

package com.example.hspedu;

import java.util.HashSet;
import java.util.Objects;

public class exercise01 {
    public static void main(String[] args) {
        HashSet hashSet = new HashSet();
        hashSet.add(new Employee("tom",12));
        hashSet.add(new Employee("milan",12));
        hashSet.add(new Employee("tom",12));

        System.out.println("hashSet = " + hashSet);

    }


}

class Employee{
    private String name;
    private int age;

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

    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;
    }

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

    //

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Employee employee = (Employee) o;
        return age == employee.age &&
                name.equals(employee.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }
}

最后结果

下面是一道附加题,答案是总计写的,如果大家觉得有不足之处或者其他的思路,欢迎指出

package com.example.hspedu;

import java.util.HashSet;
import java.util.Objects;

public class exercise02 {
    public static void main(String[] args) {
        HashSet hashSet = new HashSet();
        hashSet.add(new Employee2("jack",3000,new MyDate(1999,12,20)));
        hashSet.add(new Employee2("tom",5000,new MyDate(1998,6,20)));
        hashSet.add(new Employee2("jack",3000,new MyDate(1999,12,20)));

        System.out.println("hashSet = " + hashSet);

    }
}

class Employee2{
    private String name;
    private double sal;
    private MyDate birthday;

    public Employee2(String name, double sal, MyDate birthday) {
        this.name = name;
        this.sal = sal;
        this.birthday = birthday;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Employee2 employee2 = (Employee2) o;
        return Objects.equals(name, employee2.name) &&
                Objects.equals(birthday, employee2.birthday);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, birthday);
    }

    @Override
    public String toString() {
        return "Employee2{" +
                "name='" + name + ''' +
                ", sal=" + sal +
                ", birthday=" + birthday +
                '}';
    }

    public String getName() {
        return name;
    }

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

    public double getSal() {
        return sal;
    }

    public void setSal(double sal) {
        this.sal = sal;
    }

    public MyDate getBirthday() {
        return birthday;
    }

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

class MyDate{
    private int year;
    private int month;
    private int day;

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

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

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        MyDate myDate = (MyDate) o;
        return year == myDate.year &&
                month == myDate.month &&
                day == myDate.day;
    }

    @Override
    public int hashCode() {
        return Objects.hash(year, month, 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;
    }
}

最后结果