The java.util.WeakHashMap.isEmpty() method of HashMap class is used to check for the emptiness of the map. The method returns True if no key-value pair or mapping is present in the map else False.
Syntax:
Weak_Hash_Map.isEmpty()
Parameters: The method does not take any parameters.
Return Value: The method returns boolean true if the map is empty or does not contain any mapping pairs else boolean false.
Below programs illustrates the working of java.util.WeakHashMap.isEmpty() method:
Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the isEmpty() 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( "The Mappings are: " +
weak_hash);
// Checking for the emptiness of Map
System.out.println( "Is the map empty? " +
weak_hash.isEmpty());
}
} |
The Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20} Is the map empty? false
Program 2: For an empty WeakHashMap
// Java code to illustrate the isEmpty() 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>();
// Displaying the WeakHashMap
System.out.println( "The Mappings are: " +
weak_hash);
// Checking for the emptiness of Map
System.out.println( "Is the map empty? " +
weak_hash.isEmpty());
}
} |
The Mappings are: {} Is the map empty? true
Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.
All methods of Java.util.WeakHashmap Class