Java ConcurrentHashMap values()用法及代碼示例

Java中ConcurrentHashMap類的values()方法用於從Map值中創建一個集合。它本質上返回ConcurrentHashMap中的值的Collection視圖。

用法:

ConcurrentHashMap.values()

參數：該方法不接受任何參數。

返回值：該方法用於返回包含Map所有值的集合視圖。

下麵的程序用於說明ConcurrentHashMap.values()方法的用法：

示例1:將字符串值映射到整數鍵。

// 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()); 
    } 
}

輸出：

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

示例2:將整數值映射到字符串鍵。

// 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()); 
    } 
}

輸出：

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

注意：可以對具有不同數據類型的變化和組合的任何類型的映射執行相同的操作。

相關用法

注：本文由純淨天空篩選整理自Chinmoy Lenka大神的英文原創作品 ConcurrentHashMap values() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。