WeakHashMap isEmpty() Method in Java with Examples
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("Beginner", 10); weak_hash.put("4", 15); weak_hash.put("Beginner", 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()); } } |
Output:
The Mappings are: {Welcomes=25, 4=15, You=30, Beginner=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()); } } |
Output:
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
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