The java.util.IdentityHashMap.size() method of IdentityHashMap class is used to get the size of the IdentityHashMap which refers to the number of the key-value pair or mappings in the Map.
Syntax:
Identity_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.IdentityHashMap.size() method:
Program 1:
// Java code to illustrate the size() method import java.util.*;
public class Identity_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty IdentityHashMap
Map<Integer, String> identity_hash = new IdentityHashMap<Integer, String>();
// Mapping string values to int keys
identity_hash.put( 10 , "Geeks" );
identity_hash.put( 15 , "4" );
identity_hash.put( 20 , "Geeks" );
identity_hash.put( 25 , "Welcomes" );
identity_hash.put( 30 , "You" );
// Displaying the IdentityHashMap
System.out.println( "Initial Mappings are: " +
identity_hash);
// Displaying the size of the map
System.out.println( "The size of the map is " +
identity_hash.size());
}
} |
Output:
Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15} The size of the map is 4
Program 2:
// Java code to illustrate the size() method import java.util.*;
public class Identity_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty IdentityHashMap
Map<String, Integer> identity_hash = new IdentityHashMap<String, Integer>();
// Mapping int values to string keys
identity_hash.put( "Geeks" , 10 );
identity_hash.put( "4" , 15 );
identity_hash.put( "Geeks" , 20 );
identity_hash.put( "Welcomes" , 25 );
identity_hash.put( "You" , 30 );
// Displaying the IdentityHashMap
System.out.println( "Initial Mappings are: " +
identity_hash);
// Displaying the size of the map
System.out.println( "The size of the map is " +
identity_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.