Java 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所映射的值。如果地图中没有该键的映射，它将返回NULL。

语法

WeakHashMap.get(Object key_element)

参数： 该方法需要一个对象类型的参数key_element，指的是要获取其相关值的键。

返回值： 该方法返回与参数中key_element相关的值。

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

程序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

程序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： 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。