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WeakHashMap isEmpty() Method in Java with Examples

  • Difficulty Level : Basic
  • Last Updated : 19 Jul, 2018

The java.util.WeakHashMap.isEmpty() method of HashMap class is used to check for the emptiness of the map. The method returns True if no key-value pair or mapping is present in the map else False.

Syntax:

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Weak_Hash_Map.isEmpty()

Parameters: The method does not take any parameters.

Return Value: The method returns boolean true if the map is empty or does not contain any mapping pairs else boolean false.



Below programs illustrates the working of java.util.WeakHashMap.isEmpty() method:
Program 1: Mapping String Values to Integer Keys.




// Java code to illustrate the isEmpty() 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("The Mappings are: "+
                                      weak_hash);
  
        // Checking for the emptiness of Map
        System.out.println("Is the map empty? "+
                           weak_hash.isEmpty());
    }
}
Output:
The Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
Is the map empty? false

Program 2: For an empty WeakHashMap




// Java code to illustrate the isEmpty() 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>();
  
        // Displaying the WeakHashMap
        System.out.println("The Mappings are: "+
                                      weak_hash);
  
        // Checking for the emptiness of Map
        System.out.println("Is the map empty? "+
                            weak_hash.isEmpty());
    }
}
Output:
The Mappings are: {}
Is the map empty? true

Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.

All methods of Java.util.WeakHashmap Class




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