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HashMap isEmpty() Method in Java

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  • Difficulty Level : Basic
  • Last Updated : 26 Nov, 2018

The java.util.HashMap.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:

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.HashMap.isEmpty() method:
Program 1: Mapping String Values to Integer Keys.




// Java code to illustrate the isEmpty() method
import java.util.*;
  
public class Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        HashMap<String, Integer> hash_map = new HashMap<String, Integer>();
  
        // Mapping int values to string keys
        hash_map.put("Geeks", 10);
        hash_map.put("4", 15);
        hash_map.put("Geeks", 20);
        hash_map.put("Welcomes", 25);
        hash_map.put("You", 30);
  
        // Displaying the HashMap
        System.out.println("The Mappings are: " + hash_map);
  
        // Checking for the emptiness of Map
        System.out.println("Is the map empty? " + hash_map.isEmpty());
    }
}

Output:

The Mappings are: {4=15, Geeks=20, You=30, Welcomes=25}
Is the map empty? false

Program 2: For an empty HashMap




// Java code to illustrate the isEmpty() method
import java.util.*;
  
public class Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        HashMap<String, Integer> hash_map = new HashMap<String, Integer>();
  
        // Displaying the HashMap
        System.out.println("The Mappings are: " + hash_map);
  
        // Checking for the emptiness of Map
        System.out.println("Is the map empty? " + hash_map.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.


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