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How To Remove Duplicate Values From List Using Java Stream API?

Introduction

Stream API feature was introduced in Java 8 but it is still confusing for many and also many have not even used it a single time. I will try to explain Java Stream concepts with simple examples in Learn Stream API in Java with Examples series.

In this post, we will learn to remove duplicates from a Java List using Stream APIs i.e. distinct() method.

YouTube Tutorials

If you want to learn from a video tutorial then please refer to the below video –

Remove Duplicate Values From List Without Stream API

There are multiple logics to remove duplicates from a List in Java. We will implement a simple logic here. Suppose we have a List of integer or string values.

  1. Create an empty list.
  2. Iterate the original list and add its element to the new list if the element is not present in the new list.

Java Program

Output

Remove Duplicate Values From List With Stream API

There is nothing wrong with the above logic but Java stream APIs can help to eliminate all these headaches. It is always good to use predefined methods rather than writing your own logic until you are preparing for interviews. Let’s rewrite the program with the help of Stream APIs.

  1. Get a sequential stream of List using stream() method.
  2. Call distinct() method to remove all duplicates from the list.
  3. Collect results into a List.

Java Program

Output

GitHub Repo Link

https://github.com/amod-mahajan/MSE_LearnJavaStreamsWithExamples.git

If you have any doubt, feel free to comment below.
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Author: Amod Mahajan

A software Tester who is paid to judge products developed by others. Currently getting paid in American Dollars. Writing technical posts and creating YouTube videos are my hobbies.

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