WeakHashMap size() method in Java

The java.util.WeakHashMap.size() method of WeakHashMap class is used to get the size of the map which refers to the number of the key-value pair or mappings in the Map.

Syntax:

WeaK_Hash_Map.size()

Parameters: The method does not take any parameters.

Return Value: The method returns the size of the map which also means the number of key-value pairs present in the map.

Below programs illustrate the java.util.WeakHashMap.size() method:

Program 1:

// Java code to illustrate the size() 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, "Beginner"); 
        weak_hash.put(15, "4"); 
        weak_hash.put(20, "Beginner"); 
        weak_hash.put(25, "Welcomes"); 
        weak_hash.put(30, "You"); 
  
        // Displaying the WeakHashMap 
        System.out.println("Initial Mappings are: " +  
                                           weak_hash); 
  
        // Displaying the size of the map 
        System.out.println("The size of the map is " +  
                                    weak_hash.size()); 
    } 
} 

Output:

Initial Mappings are: {30=You, 15=4, 10=Beginner, 25=Welcomes, 20=Beginner}
The size of the map is 5

Program 2:

// Java code to illustrate the size() 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("Beginner", 10); 
        weak_hash.put("4", 15); 
        weak_hash.put("Beginner", 20); 
        weak_hash.put("Welcomes", 25); 
        weak_hash.put("You", 30); 
  
        // Displaying the WeakHashMap 
        System.out.println("Initial Mappings are: " +  
                                           weak_hash); 
  
        // Displaying the size of the map 
        System.out.println("The size of the map is " +  
                                     weak_hash.size()); 
    } 
} 

Output:

Initial Mappings are: {Welcomes=25, 4=15, You=30, Beginner=20}
The size of the map is 4

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

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