Java WeakHashMap get()用法及代码示例

WeakHashMap类的java.util.WeakHashMap.get()方法用于检索或获取由参数中提到的特定键映射的值。当映射不包含键的此类映射时，它将返回NULL。

用法:

WeakHashMap.get(Object key_element)

参数：该方法采用对象类型的一个参数key_element，表示应该获取其关联值的键。

返回值：该方法返回与参数中的key_element关联的值。

以下示例程序旨在说明java.util.WeakHashMap.get()方法的用法：

示例1:

// Java code to illustrate the get() 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); 
  
        // Getting the value of 25 
        System.out.println("The Value is: " + weak_hash.get(25)); 
  
        // Getting the value of 10 
        System.out.println("The Value is: " + weak_hash.get(10)); 
    } 
}

输出：

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

示例2:

// Java code to illustrate the get() 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); 
  
        // Getting the value of "Geeks" 
        System.out.println("The Value is: " + weak_hash.get("Geeks")); 
  
        // Getting the value of "You" 
        System.out.println("The Value is: " + weak_hash.get("You")); 
    } 
}

输出：

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

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 WeakHashMap get() 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。