Java ConcurrentHashMap values()用法及代码示例

Java中ConcurrentHashMap类的values()方法用于从Map值中创建一个集合。它本质上返回ConcurrentHashMap中的值的Collection视图。

用法:

ConcurrentHashMap.values()

参数：该方法不接受任何参数。

返回值：该方法用于返回包含Map所有值的集合视图。

下面的程序用于说明ConcurrentHashMap.values()方法的用法：

示例1:将字符串值映射到整数键。

// Java code to illustrate the values() method 
  
import java.util.*; 
import java.util.concurrent.*; 
  
public class ConcurrentHashMapDemo { 
    public static void main(String[] args) 
    { 
  
        // Creating an empty ConcurrentHashMap 
        ConcurrentHashMap<Integer, String> hash_map 
            = new ConcurrentHashMap<Integer, String>(); 
  
        // Mapping string values to int keys 
        hash_map.put(10, "Geeks"); 
        hash_map.put(15, "4"); 
        hash_map.put(20, "Geeks"); 
        hash_map.put(25, "Welcomes"); 
        hash_map.put(30, "You"); 
  
        // Displaying the HashMap 
        System.out.println("Initial Mappings are: "
                           + hash_map); 
  
        // Using keySet() to get the set view of keys 
        System.out.println("The Collection is: "
                           + hash_map.values()); 
    } 
}

输出：

Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
The Collection is: [Geeks, Welcomes, Geeks, You, 4]

示例2:将整数值映射到字符串键。

// Java code to illustrate the values() method 
  
import java.util.*; 
import java.util.concurrent.*; 
  
public class ConcurrentHashMapDemo { 
    public static void main(String[] args) 
    { 
  
        // Creating an empty ConcurrentHashMap 
        ConcurrentHashMap<String, Integer> 
            hash_map = new ConcurrentHashMap<String, 
                                             Integer>(); 
  
        // Mapping int values to string keys 
        hash_map.put("Geeks", 10); 
        hash_map.put("4", 15); 
        hash_map.put("Geeks", 20); 
        hash_map.put("Welcomes", 25); 
        hash_map.put("You", 30); 
  
        // Displaying the HashMap 
        System.out.println("Initial Mappings are: "
                           + hash_map); 
  
        // Using keySet() to get the set view of keys 
        System.out.println("The Collection is: "
                           + hash_map.values()); 
    } 
}

输出：

Initial Mappings are: {4=15, Geeks=20, You=30, Welcomes=25}
The Collection is: [15, 20, 30, 25]

注意：可以对具有不同数据类型的变化和组合的任何类型的映射执行相同的操作。

相关用法

注：本文由纯净天空筛选整理自Chinmoy Lenka大神的英文原创作品 ConcurrentHashMap values() 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。