Java Map equals()用法及代码示例

Java中的java.util.Map.equals()方法用于检查两个映射之间的相等性。它验证作为参数传递的一个映射的元素是否等于该映射的元素。

用法:

boolean equals(object obj)

参数：该方法接受此映射类型的一个参数obj，表示要与该映射检查其相等性的映射。

返回值：如果两个对象映射都相等，则该方法返回true，否则返回false。

下面的程序演示了java.util.Map.equals()方法：
示例1:

// Java code to illustrate the equals() method 
import java.util.*; 
  
public class Map_Demo { 
    public static void main(String[] args) 
    { 
        // Creating an empty Map 
        Map<Integer, String> map1 = new HashMap<Integer, String>(); 
        Map<Integer, String> map2 = new HashMap<Integer, String>(); 
  
        // Mapping string values to int keys 
        map1.put(10, "Geeks"); 
        map1.put(15, "4"); 
        map1.put(20, "Geeks"); 
        map1.put(25, "Welcomes"); 
        map1.put(30, "You"); 
  
        // Mapping string values to int keys 
        map2.put(10, "Geeks"); 
        map2.put(15, "4"); 
        map2.put(20, "Geeks"); 
        map2.put(25, "Welcomes"); 
        map2.put(30, "You"); 
  
        // Displaying the Map1 
        System.out.println("First Map: "
                           + map1); 
  
        // Displaying the Map2 
        System.out.println("Second Map: "
                           + map2); 
  
        // Checking the equality 
        System.out.println("Equality: " + map1.equals(map2)); 
    } 
}

输出：

First Map: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Second Map: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Equality: true

示例2:

// Java code to illustrate the equals() method 
import java.util.*; 
  
public class Map_Demo { 
    public static void main(String[] args) 
    { 
        // Creating an empty Map 
        Map<Integer, String> map1 = new HashMap<Integer, String>(); 
        Map<Integer, String> map2 = new HashMap<Integer, String>(); 
  
        // Mapping string values to int keys for map1 
        map1.put(10, "Geeks"); 
        map1.put(15, "4"); 
        map1.put(20, "Geeks"); 
        map1.put(25, "Welcomes"); 
        map1.put(30, "You"); 
  
        // Mapping string values to int keys for map2 
        map2.put(10, "Geeks"); 
        map2.put(15, "4"); 
        map2.put(20, "Geek"); 
        map2.put(25, "Welcomes"); 
        map2.put(30, "You"); 
  
        // Displaying the map 1 
        System.out.println("First Map: " + map1); 
  
        // Displaying the map 2 
        System.out.println("Second Map: " + map2); 
  
        // Displaying the equality 
        System.out.println("Equality: " + map1.equals(map2)); 
    } 
}

输出：

First Map: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Second Map: {20=Geek, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Equality: false

参考： https://docs.oracle.com/javase/7/docs/api/java/util/Map.html#equals(java.lang.Object)

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注：本文由纯净天空筛选整理自gopaldave大神的英文原创作品 Map equals() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。