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WeakHashMap size() method in Java

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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, "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);
  
        // 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=Geeks, 25=Welcomes, 20=Geeks}
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("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);
  
        // 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, Geeks=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.

Last Updated : 20 Jul, 2018
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