Java Hashmap keySet() Method

hashmap keySet method

What is a Hashmap?

Hashmap class is a part of java.util package. In hashmap key/value pairs can be stored , but no duplicate key is allowed.If a duplicate key is inserted it will replace the present value with the new value. Many built-in methods are there in hashmap class which makes it easy to perform operations on them, like insertion , deletion and many more. One of those methods is Java Hashmap keySet() Method. 

To know more about Hashmap keySet() Method read the complete article.

Java Hashmap keySet() Method

The hashmap keySet() method is used make a set of keys present in the hashmap. This method returns a set of keys. Below in this page you can find it’s syntax, return values, parameters with detailed examples.

Syntax :


Return values :

This methos returns a set of keys present in the hashmap.
Java hashmap keySet method

Hashmap keySet() Method Examples

Example :

import java.util.*;

public class Main
    public static void main (String[]args)

        // Creating an empty HashMap
        HashMap < String, Integer > hash_map_1 =
                new HashMap < String, Integer > ();

        // Mapping string values to int keys in a empty hashmap
        hash_map_1.put ("Maths", 80);
        hash_map_1.put ("English", 75);
        hash_map_1.put ("Hindi", 85);
        hash_map_1.put ("Science", 90);

        System.out.println("Original hashmap : " + hash_map_1);

       //printing the keys present in hte hashmap
        System.out.println("Keys present in the hashmap : "+hash_map_1.keySet());


Output :

Original hashmap : {Maths=80, English=75, Science=90, Hindi=85}
Keys present in the hashmap : [Maths, English, Science, Hindi]

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