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() methodimport 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() methodimport 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.
