The java.util.WeakHashMap.entrySet() method in Java is used to create a set out of the same elements contained in the map. It basically returns a set view of the weak hash map or we can create a new set and store the map elements into them.
Syntax:
weak_hash_map.entrySet()
Parameters: The method does not take any parameter.
Return Value: The method returns a set having same elements as the map.
Below programs illustrate the java.util.WeakHashMap.entrySet() Method:
Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the entrySet() 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);
// Using entrySet() to get the set view
System.out.println( "The set is: " + weak_hash.entrySet());
}
} |
Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks} The set is: [30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks]
Program 2: Mapping Integer Values to String Keys.
// Java code to illustrate the entrySet() 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);
// Using entrySet() to get the set view
System.out.println( "The set is: " + weak_hash.entrySet());
}
} |
Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20} The set is: [Welcomes=25, 4=15, You=30, Geeks=20]
Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.