java中set集合如何去除重复元素

set集合是能够重复的元素集合;
用set集合添加一个学生对象元素时:java

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

public class People {
    String name;
    int ages;

    public People(String name, int ages) {
        this.name = name;
        this.ages = ages;
    }

    public static void main(String[] args) {
        //建立集合对象
        Set study = new HashSet();
        //List study=new ArrayList();
        study.add(new People("张三", 45));
        study.add(new People("李四", 37));
        study.add(new People("王五", 54));
        study.add(new People("张三", 45));
        study.add(new People("张三", 25));
        //建立迭代器对象
        Iterator it = study.iterator();
        while (it.hasNext()) {
            People str = (People) it.next();
            System.out.println(str.toSring());
        }
    }
    //重写头String方法,使输出的样式按照本身所定义的格式输出
    public String toSring() {
        return name + " " + ages;
    }
}

此时的运行结果:

如何除去重复的元素信息呢?
须要重写equals()和hashCode()方法;
代码以下web

public class People {
    String name;
    int ages;
    public People(String name, int ages) {
        this.name = name;
        this.ages = ages;
    }
    public static void main(String[] args) {
        //建立集合对象
        Set study = new HashSet();
        //List study=new ArrayList();
        study.add(new People("张三", 45));
        study.add(new People("李四", 37));
        study.add(new People("王五", 54));
        study.add(new People("张三", 45));
        study.add(new People("张三", 25));
        //建立迭代器对象
        Iterator it = study.iterator();
        while (it.hasNext()) {
            People str = (People) it.next();
            System.out.println(str.toSring());
        }
    }
    public String toSring() {
        return name + " " + ages;
    }
    //重写equals()方法:判断姓名和年龄二者是否都相同;
    @Override
    public boolean equals(Object obj) {
        People p = (People) obj;
        return p.name == this.name && p.ages == this.ages;
    }
    //重写hashcode()方法:
    @Override
    public int hashCode() {
        return name.hashCode();
    }
}

运行结果:

经过以上代码,就能够出去set集合中的重复元素!ide

但愿对你们有所帮助!svg