Java HashSet remove() 方法

remove() 是Java HashSet类的方法，用于HashSet中删除指定的元素。

1 语法

public boolean remove(Object o)  

2 参数

需要删除的对象。

3 返回值

删除的对象存在返回true，否则返回false。

4 HashSet remove()示例1

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java HashSet.remove()方法的例子
 */
import java.util.*;

public class Demo {

    public static void main(String[] args) {
        HashSet<String> set=new HashSet<String>();
        set.add("Eric");
        set.add("Jack");
        set.add("Mark");
        set.add("Lucy");
        //打印HashSet
        System.out.println("HashSet: " + set);
        //删除元素
        set.remove("Jack");
        //删除元素后的HashSet
        System.out.println("HashSet after removing elements: " + set);
    }
}

输出结果为：

HashSet: [Eric, Mark, Lucy, Jack]
HashSet after removing elements: [Eric, Mark, Lucy]

5 HashSet remove()示例2

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java HashSet.remove()方法的例子
 */
import java.util.*;

public class Demo {

    public static void main(String[] args) {
        HashSet<Integer> hashSetObject = new HashSet <>();
        hashSetObject.add(45);
        hashSetObject.add(67);
        hashSetObject.add(98);
        hashSetObject.add(24);
        //打印HashSet
        System.out.println("HashSet: " + hashSetObject);
        //删除元素
        hashSetObject.remove(98);
        hashSetObject.remove(24);
        //打印HashSet
        System.out.println("HashSet after removing elements: " + hashSetObject);
    }
}

输出结果为：

HashSet: [98, 67, 24, 45]
HashSet after removing elements: [67, 45]

6 HashSet remove()示例3

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java HashSet.remove()方法的例子
 */
import java.util.*;
class Book {
    int id;
    String name,author,publisher;
    int quantity;
    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }
}

public class Demo {

    public static void main(String[] args) {
        HashSet<Book> set=new HashSet<Book>();
        //创建Book
        Book b1=new Book(101,"Thinking in Java","张三","出版社1",8);
        Book b2=new Book(102,"深入理解Java虚拟机","李四","出版社2",4);
        Book b3=new Book(103,"Head First 设计模式","王五","出版社3",6);
        //添加Book
        set.add(b1);
        set.add(b2);
        set.add(b3);
        //遍历HashSet
        for(Book b:set){
            System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);
        }
        //删除元素
        set.remove(b2);
        System.out.println("Books after remove method:");
        for(Book b:set){
            System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);
        }
    }
}

输出结果为：

102 深入理解Java虚拟机 李四 出版社2 4
101 Thinking in Java 张三 出版社1 8
103 Head First 设计模式 王五 出版社3 6
Books after remove method:
101 Thinking in Java 张三 出版社1 8
103 Head First 设计模式 王五 出版社3 6