Java中的WeakHashMap get()方法

WeakHashMap 类的Java.util.WeakHashMap.get() 方法用于检索或获取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，它返回 NULL。

句法：

WeakHashMap.get(Object key_element)

参数：该方法接受一个对象类型的参数key_element ，并引用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。

下面的程序说明了Java.util.WeakHashMap.get() 方法的工作：

方案一：

// 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 weak_hash = new WeakHashMap();
  
        // 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

方案二：

// 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 weak_hash = new WeakHashMap();
  
        // 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：可以对任何类型的映射执行相同的操作，这些映射具有不同数据类型的变化和组合。