Java WeakHashMap values()方法

Java中HashMap类的java.util.WeakHashMap.values()方法用于从地图的值中创建一个集合。它基本上返回地图中数值的一个集合视图。

语法

Weak_Hash_Map.values()

参数： 该方法不接受任何参数。

返回值： 该方法用于返回一个包含地图所有值的集合视图。

下面的程序用来说明java.util.WeakHashMap.values()方法的工作：
程序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]

程序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： 同样的操作可以通过不同数据类型的变化和组合对任何类型的Mapping进行操作。