Java中的LinkedHashSet的equals()方法与示例

java.util.LinkedHashSet 类的 equals() 方法用于将指定的对象与此集合进行比较以判断是否相等。当且仅当指定的对象也是一个集合、两个集合具有相同的大小，并且两个集合中对应的元素对都相等时返回true。换句话说，如果两个集合包含相同的元素，顺序不限，则定义这两个集合相等。 (如果e1=null? e2=null：e1.equals(e2))，则e1和e2是相等的。)

语法:

public boolean equals(Object o)

参数: 此方法将 object o 作为参数，与此集合进行比较以进行相等性检查。

返回值: 如果指定的对象等于此集合，则此方法将返回 true 。下面是举例说明equals()方法的用法。

示例1：

// Java program to demonstrate equals()
// method of LinkedHashSet
 
import java.util.*;
 
public class GFG {
    public static void main(String[] argv)
    {
 
        // Creating object of LinkedHashSet<String>
        LinkedHashSet<String> set1
            = new LinkedHashSet<String>();
 
        // Populating set1
        set1.add("A");
        set1.add("B");
        set1.add("C");
        set1.add("D");
        set1.add("E");
 
        // print set1
        System.out.println("First LinkedHashSet: " + set1);
 
        // Creating another object of LinkedHashSet<String>
        LinkedHashSet<String> set2
            = new LinkedHashSet<String>();
 
        // Populating set2
        set2.add("A");
        set2.add("B");
        set2.add("C");
        set2.add("D");
        set2.add("E");
 
        // print set2
        System.out.println("Second LinkedHashSet: " + set2);
 
        // comparing first LinkedHashSet to another
        // using equals() method
        boolean value = set1.equals(set2);
 
        // print the value
        System.out.println("Are both set equal: " + value);
    }
}

输出：

First LinkedHashSet: [A, B, C, D, E]
Second LinkedHashSet: [A, B, C, D, E]
Are both set equal: true

示例2：

// Java program to demonstrate equals()
// method of LinkedHashSet
 
import java.util.*;
 
public class GFG1 {
    public static void main(String[] argv)
    {
 
        // Creating object of LinkedHashSet
        LinkedHashSet<Integer>
            set1 = new LinkedHashSet<Integer>();
 
        // Populating set1
        set1.add(10);
        set1.add(20);
        set1.add(30);
        set1.add(40);
        set1.add(50);
 
        // print set1
        System.out.println("First LinkedHashSet: "
                           + set1);
 
        // Creating another object of LinkedHashSet
        LinkedHashSet<Integer>
            set2 = new LinkedHashSet<Integer>();
 
        // Populating set2
        set2.add(10);
        set2.add(20);
        set2.add(30);
 
        // print set2
        System.out.println("Second LinkedHashSet: "
                           + set2);
 
        // comparing first LinkedHashSet to another
        // using equals() method
        boolean value = set1.equals(set2);
 
        // print the value
        System.out.println("Are both set equal: "
                           + value);
    }
}

输出：

First LinkedHashSet: [10, 20, 30, 40, 50]
Second LinkedHashSet: [10, 20, 30]
Are both set equal: false