Java Hashmap computeIfAbsent() Method

hashmap computeIfAbsent method

Java Classes

Java is a Object-Oriented programming language. In java everything is based on classes and objects. Basically a class is collection of objects having same properties. Different classes are present in different packages. Hashmap class is a part of java.util package. In hashmap key/value pairs can be stored , but no duplicate key is allowed. Many built-in methods are there in hashmap class. One of those methods is Java Hashmap computeIfAbsent() Method. 

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

Java Hashmap computeIfAbsent() Method

The hashmap computeIfAbsent() method is used to assign a new value to the specified key if the key is not present in the hashmap. Below in this page you can find it’s syntax, return values, parameters with detailed examples.

Syntax :

hashmap.computeIfAbsent(Key , Function);

Return Values :

Value :- value which is associated with the key.

Hashmap forEach() Method Example

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 ("Java", 10);
    hash_map_1.put ("Hashmap", 20);
    hash_map_1.put ("computeIfAbsent", 30);
    hash_map_1.put ("Method", 40);

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

    int value = hash_map_1.computeIfAbsent ("PrepInsta", k->5 * 10);
      System.out.println ("Value mapped to key PrepInsta : " + value);

    //Printing updated hashmap
      System.out.println ("Updated hashamap : " + hash_map_1);

Output :

Original hashmap : {Java=10, Hashmap=20, computeIfAbsent=30, Method=40}
Value mapped to key PrepInsta : 50
Updated hashamap : {Java=10, Hashmap=20, computeIfAbsent=30, PrepInsta=50, Method=40}

Prime Course Trailer

Related Banners

Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription

Get over 200+ course One Subscription

Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others

Checkout list of all the video courses in PrepInsta Prime Subscription

Checkout list of all the video courses in PrepInsta Prime Subscription