HashSet的运用

TestHashSet.java

package com.sxt.set1;
/*
 * Set接口   唯一：元素唯一（不重复）
 *                  无序：不是按照添加的顺序显示数据
 * 采用哈希表的方式存储
 * 根据哈希地址（取模）存储 调用equals()方法 若没有直接存储 若有不存储 保证了唯一性
 * 
 * Integer添加后  会自动排序（由于哈希表的存储方式，整数的哈希码是本身）
 * 自定义的类型 用HashSet方式存储需要重写 HashSet()方法、equals()方法、toString()方法
 */
import java.util.HashSet;
import java.util.Set;

public class TestHashSet {
    public static void main(String[] args) {
        Set<Person> arr = new HashSet<>();
        arr.add(new Person("ccc", "女", 32.2));
        arr.add(new Person("ccc", "女", 32.2));
        System.out.println(arr);
    }
}

Person.java

package com.sxt.set1;

public class Person {
    private String name;
    private String sex;
    private double score;
    
    public Person() {
        super();
    }
    
    public Person(String name, String sex, double score) {
        super();
        this.name = name;
        this.sex = sex;
        this.score = score;
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public double getScore() {
        return score;
    }
    public void setScore(double score) {
        this.score = score;
    }

    @Override
    public String toString() {
        return "Person [name=" + name + ", sex=" + sex + ", score=" + score + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        long temp;
        temp = Double.doubleToLongBits(score);
        result = prime * result + (int) (temp ^ (temp >>> 32));
        result = prime * result + ((sex == null) ? 0 : sex.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Person other = (Person) obj;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        if (Double.doubleToLongBits(score) != Double.doubleToLongBits(other.score))
            return false;
        if (sex == null) {
            if (other.sex != null)
                return false;
        } else if (!sex.equals(other.sex))
            return false;
        return true;
    }
    
}