Java EnumMap putAll(map)用法及代码示例

Java中的Java.util.EnumMap.putAll(map)方法用于将所有映射从一个映射复制到一个新的映射。较旧的映射将替换为较新的映射。

用法:

void putAll(map)

参数：该方法采用一个参数Map。它是要复制到较新的Map。

返回值该方法不返回任何值。

以下示例程序旨在说明putAll()方法：

示例1:

// Java program to demonstrate keySet() 
import java.util.*; 
  
// An enum of geeksforgeeks 
public enum gfg { 
    Global_today, 
    India_today, 
    China_today 
}; 
  
class Enum_demo { 
    public static void main(String[] args) 
    { 
  
        EnumMap<gfg, Integer> mp1 =  
                     new EnumMap<gfg, Integer>(gfg.class); 
  
        EnumMap<gfg, Integer> mp2 =  
                     new EnumMap<gfg, Integer>(gfg.class); 
  
        // Values are associated 
        mp1.put(gfg.Global_today, 799); 
        mp1.put(gfg.India_today, 69); 
  
        // Copies all the mappings of mp1 to mp2 
        mp2.putAll(mp1); 
  
        // Prints the first map 
        System.out.println("Mappings in Map1: " + mp1); 
  
        // Prints the second map 
        System.out.println("Mappings in Map2: " + mp2); 
    } 
}

输出：

Mappings in Map1: {Global_today=799, India_today=69}
Mappings in Map2: {Global_today=799, India_today=69}

示例2:

// Java program to demonstrate the working of keySet() 
import java.util.*; 
  
// an enum of geeksforgeeks 
// visitors in India and United States 
public enum gfg { 
  
    India_today, 
    United_States_today 
} 
; 
  
class Enum_demo { 
    public static void main(String[] args) 
    { 
  
        EnumMap<gfg, String> mp1 =  
                     new EnumMap<gfg, String>(gfg.class); 
  
        EnumMap<gfg, String> mp2 =  
                     new EnumMap<gfg, String>(gfg.class); 
  
        // Values are associated 
        mp1.put(gfg.India_today, "61.8%"); 
        mp1.put(gfg.United_States_today, "18.2%"); 
  
        // Copies all the mappings of mp1 to mp2 
        mp2.putAll(mp1); 
  
        // Prints the first map 
        System.out.println("Mappings in Map1: " + mp1); 
  
        // Prints the second map 
        System.out.println("Mappings in Map2: " + mp2); 
    } 
}

输出：

Mappings in Map1: {India_today=61.8%, United_States_today=18.2%}
Mappings in Map2: {India_today=61.8%, United_States_today=18.2%}

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注：本文由纯净天空筛选整理自akash1295大神的英文原创作品 EnumMap putAll(map) Method in Java。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。