Java WeakHashMap get()用法及代碼示例

WeakHashMap類的java.util.WeakHashMap.get()方法用於檢索或獲取由參數中提到的特定鍵映射的值。當映射不包含鍵的此類映射時，它將返回NULL。

用法:

WeakHashMap.get(Object key_element)

參數：該方法采用對象類型的一個參數key_element，表示應該獲取其關聯值的鍵。

返回值：該方法返回與參數中的key_element關聯的值。

以下示例程序旨在說明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)); 
    } 
}

輸出：

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")); 
    } 
}

輸出：

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

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 WeakHashMap get() Method in Java。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。