Java HashSet size() Method

Java HashMap size() Method

Last Updated : 20 Jan, 2025

The size() method of the Java HashMap class is used to retrieve the number of key-value pairs currently stored in the HashMap.

Example 1: This example demonstrates the use of the size() method to get the number of elements in the HashMap.

Java

// Java program to demonstrates the working of size()
import java.util.HashMap;

public class Geeks {
    public static void main(String[] args)
    {
        // Creating a HashMap
        HashMap<String, Integer> hm = new HashMap<>();

        // Adding elements to the HashMap
        hm.put("Java", 10);
        hm.put("C++", 20);
        hm.put("python", 30);

        System.out.println("Size of the HashMap: "
                           + hm.size());
    }
}

Output

Size of the HashMap: 3

Syntax of HashMap size() Method

public int size()

Return Type: It returns an int value representing the number of key-value mapping in the HashMap.

Example 2: This example demonstrates the size of the HashMap after removing an element.

Java

// Java program to demomnstrates the use 
// of size() to track the number of entries 
// in the HashMap
import java.util.HashMap;

public class Geeks {
    public static void main(String[] args)
    {
        // Creating a HashMap
        HashMap<String, Integer> hm = new HashMap<>();

        // Adding elements to the HashMap
        hm.put("Java", 10);
        hm.put("C++", 20);
        hm.put("Python", 30);
        hm.put("JavaScript", 40);
      
        System.out.println("Size of the HashMap: "
                           + hm.size());
      
        // Removing an element
        hm.remove("Python");
      
        // Displaying the size of the 
        // HashMap after removal
        System.out.println(
            "Size of the HashMap After removal: "
            + hm.size());
    }
}

Output

Size of the HashMap: 4
Size of the HashMap After removal: 3

Java HashSet size() Method

chinmoy lenka

Improve

Article Tags :

Practice Tags :

Similar Reads

HashMap size() Method in Java

The size() method of the Java HashMap class is used to retrieve the number of key-value pairs currently stored in the HashMap. Example 1: This example demonstrates the use of the size() method to get the number of elements in the HashMap. [GFGTABS] Java // Java program to demonstrates the working of

Java HashSet size() Method

The HashSet size() method in Java is used to get the size of the HashSet or the number of elements present in the HashSet. Syntax of HashSet size() Methodint size() Return Type: This method returns an integer value that represents the number of elements currently stored in the HashSet. Example: This

Java HashMap put() Method

The put() method of the Java HashMap class is used to add or update the key-value pairs in the map. If the key already exists in the map, the previous value associated with the key is replaced by the new value and If the key does not exist, the new key-value pair is added to the map. Syntax of HashM

Hashtable size() Method in Java

The java.util.Hashtable.size() method of Hashtable class is used to get the size of the table which refers to the number of the key-value pair or mappings in the Table. Syntax: Hash_Table.size() Parameters: The method does not take any parameters. Return Value: The method returns the size of the tab

IdentityHashMap size() Method in Java

The java.util.IdentityHashMap.size() method of IdentityHashMap class is used to get the size of the IdentityHashMap which refers to the number of the key-value pair or mappings in the Map. Syntax: Identity_Hash_Map.size() Parameters: The method does not take any parameters. Return Value: The method

Java HashMap putAll() Method

The putAll() method of the Java HashMap class is used to copy all key-value mappings from another map to the existing map. If a key exists in both maps, its value is updated with the value from the source map. Otherwise, new key-value pairs are added. Example 1: This example demonstrates copying all

ConcurrentHashMap size() Method in Java

The size() method in Java's ConcurrentHashMap class is used to retrieve the number of key-value mappings in the map. It has the following signature: int size() The size() method works in a concurrent environment, which means that it can be called from multiple threads without causing any data race o

HashMap values() Method in Java

The java.util.HashMap.values() method of HashMap class in Java is used to create a collection out of the values of the map. It basically returns a Collection view of the values in the HashMap. Syntax: Hash_Map.values() Parameters: The method does not accept any parameters. Return Value: The method i

EnumMap size() Method in Java

The Java.util.EnumMap.size() method in java is used to know the size of the map or the number of elements present in the map. Syntax: Enum_Map.size() Parameters: The method does not take any parameters. Return Value: The method returns the size of the map. Below programs illustrate the working of si

Java HashMap keySet() Method

The keySet() method of the Java HashMap class is used to return a set containing all the keys in the map. This set is backed by the HashMap, so if we make any changes to the HashMap, it will be reflected in the Set as well. Example 1: The below Java program demonstrates creating a HashMap, adding ke

翻译：