WeakHashMap keySet() method in Java
The java.util.WeakHashMap.keySet() method in Java is used to create a set out of the key elements contained in the hash map. It basically returns a set view of the keys or we can create a new set and store the key elements in them.
Syntax:
Weak_Hash_Map.keySet()
Parameters: The method does not take any parameter.
Return Value: The method returns a set having the keys of the weak hash map.
Below programs are used to illustrate the working of java.util.WeakHashMap.keySet() Method:
Program 1: Mapping String Values to Integer Keys.
import java.util.*;
public class Weak_Hash_Map_Demo {
public static void main(String[] args)
{
Map<Integer, String> weak_hash =
new WeakHashMap<Integer, String>();
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" );
System.out.println( "Initial Mappings are: " +
weak_hash);
System.out.println( "The set is: " +
weak_hash.keySet());
}
}
|
Output:
Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
The set is: [30, 15, 10, 25, 20]
Program 2: Mapping Integer Values to String Keys.
import java.util.*;
public class Weak_Hash_Map_Demo {
public static void main(String[] args)
{
Map<String, Integer> weak_hash =
new WeakHashMap<String, Integer>();
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 );
System.out.println( "Initial Mappings are: " +
weak_hash);
System.out.println( "The set is: " +
weak_hash.keySet());
}
}
|
Output:
Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
The set is: [Welcomes, 4, You, Geeks]
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
Like Article
Save Article
Share your thoughts in the comments
Please Login to comment...