Java WeakHashMap values()用法及代码示例

Java中HashMap类的java.util.WeakHashMap.values()方法用于从Map值中创建一个集合。它本质上返回Map中值的Collection视图。

用法:

Weak_Hash_Map.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。

以下程序用于说明java.util.WeakHashMap.values()方法的用法：
示例1:

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

输出：

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

示例2:

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

输出：

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

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。

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