The java.util.IdentityHashMap.hashCode() method in Java is used to fetch the hash code value of a particular this IdentityHashMap. A map consists of a number of buckets to store the key-value pair. Each bucket has a unique identity and when a key-value pair is inserted into a bucket, the key’s hashcode is matched with the identifier of the bucket, and if its a match the pair is stored successfully. This is how the hash code works.
Syntax:
Identity_HashMap.hashCode()
Parameters: The method does not accept any parameters.
Return Value: The method returns the hashcode value of the map.
Below programs are used to illustrate the working of java.util.IdentityHashMap.hashCode() Method:
Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the hashCode() method import java.util.*;
public class Identity_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty IdentityHashMap
IdentityHashMap<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);
// Getting the hashcode value for the map
System.out.println( "The hashcode value of the map: "
+ identity_hash.hashCode());
}
} |
Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4} The hashcode value of the map: 2043437408
Program 2: Mapping Integer Values to String Keys.
// Java code to illustrate the hashCode() 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);
// Getting the hashcode value for the map
System.out.println( "The hashcode value of the map: "
+ identity_hash.hashCode());
}
} |
Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15} The hashcode value of the map: 751311572
Note: The same operation can be performed with any type of Mapping with variation and combination of different data types.