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Remove duplicates from list java 8. println("\n2.
Remove duplicates from list java 8. Dec 22, 2022 · Java remove entries from list where certain attributes are duplicated Asked 2 years, 6 months ago Modified 2 years, 6 months ago Viewed 3k times Jul 27, 2018 · How can we remove duplicate elements from a list of String without considering the case for each word, for example consider below code snippet String str = "Kobe Is is The the best player In in Basketball basketball game . How to find duplicates in a Java List The most common approaches to removing duplicates from a List in Java include the May 4, 2021 · In this quick tutorial, I show you how to find duplicates in List in Java. The distinct () operation in Java 8 is mostly related to streams and is employed to remove duplicate elements from the stream. Aug 3, 2022 · Java Stream distinct () method returns a new stream of distinct elements. Feb 1, 2018 · I am trying to remove duplicates from the list of objects based on two properties, this question would be similar to below link but I am trying to find uniqueness based on two properties using java 8 features. newArrayList("Luke","luke");// it's guava's method list. The simplest way to remove duplicates is by converting a list to a set. In the circuit below, assume ideal op-amp, find Vout? Removing duplicate elements from an ArrayList in Java can be achieved through various methods. Approach: Get the ArrayList with repeated elements. After java 8 roll out, it has become simple filtering using functional programming language. Mar 8, 2023 · I have a list from a legacy system. So if we add the elements in a Set, it automatically discards the duplicate elements while addition itself. Learn how to remove duplicate elements from a list in Java with this comprehensive guide. How to remove duplicates from list : Here I am creating a Department class, it holds department details. distinct () method to remove duplicates from a Stream in Java 8 and beyond. Welcome to our comprehensive Java 8 tutorial, where we delve into the powerful In this video of code decode we have covered Java 8 coding Interview Questions and Answers where we have covered Find duplicates from a list using java 8Udem Jul 23, 2013 · Assuming that you use Java 8, it could be done using the Stream API with a Set<String> that will store the existing values: Map<String, String> map = new HashMap<>(); Feb 5, 2017 · Another problem with your logic you were using remove (object) rather than remove (index), which causes the first matching object to be removed. Dec 2, 2017 · In this tutorials, I am going to show you how to remove duplicate elements from the list using Java 8 syntax. Finding duplicates in a Java list? That’s actually a bit more complicated, but finding the dupes in a Lists is by no means an impossible task. The Stream API, which was unveiled in Java 8 to offer a more practical method of interacting with collections, includes this action. clear(); yourList. toCollection () method Let’s discuss each one in detail with example/explanation 1. . Convert the ArrayList to Set. Let's see an example to remove duplicates from ArrayList: May 17, 2010 · return customerId. However, this approach does not preserve the original order. can we do it in a simple way using java 8 List<Employee> employee Can we remove duplicates from it based on id property of employee. Apr 27, 2024 · Remove duplicates from an Array without Using Set To remove duplicate elements from an Array without using a Set in Java, we can follow the below algorithm: Algorithm Sort the input array using the Arrays. So it’s necessary that the stream elements have proper implementation of equals () method. Jun 4, 2025 · Removing duplicates from a List is a common operation in Java programming. Jul 11, 2025 · In this article, we'll learn several ways to remove duplicates from a list in Python. Jan 9, 2024 · It’s easy to remove duplicates from a list in Java. Feb 10, 2017 · I have a situation where I will be receiving 2+ ArrayList<Widget> and I need to be able to merge all the lists and remove any duplicate Widget so that I wind up with only 1 ArrayList<Widget> that contains all Widget s from all the merged lists, but without any duplicates. Alternatively, you can use Java 8 streams to achieve the same result using the distinct () method. Sep 7, 2012 · Just use the normal constructor: ArrayList<T> yourList; HashSet<T> set = new HashSet<T>(yourList); And you'll have a new view of the items, with duplicates removed, but you will lose ordering. out. Sep 1, 2019 · How to remove duplicates from ArrayList using Java 8. Sep 30, 2023 · Removing Duplicates from ArrayList using Java 8 Streams: Suppose you have an ArrayList of strings with duplicates, and you want to create a new ArrayList with distinct values then follow below steps Convert the ArrayList into a stream. import java. I need to remove those duplicates using Java 8 Apr 22, 2022 · 1. In order to remove duplicates from the list, we are going to use 'distinct' method of Stream API In this post, I will show you how to remove duplicate objects from a List using Java’s Comparator interface implementation based on multiple fields in a POJO. However, based on expected output, you want to preserve the order of the first matching objects. Using Stream. The distinct() method provides a clean way to ensure that your list contains only unique elements, making your code more concise and readable. println("\n2. *; Feb 12, 2022 · For finding duplicates, iterate through original List and remove elements by comparing elements in unique list and store into new Set using collect (Collectors. distinct () method Stream. Hello guys, if you wonder how to remove duplicates from Stream in Java, don't worry. Aug 18, 2020 · In this article, you'll explore the different ways to clean up and remove duplicates from the list and ArrayList. queryForList (sb. asList(new Integer[]{1,2,1,3,4,4}); To remove duplicates we can use the distinct() method. By using the distinct() method, you can easily remove duplicates from arrays of integers, strings, or even custom objects. Iterate through the array, starting from the index 1. java ? Feb 3, 2018 · Closed 7 years ago. println("1. “Remove duplicate elements from a list using Java 8 streams” is published by Namdev chavan. Aug 22, 2020 · Java 8 Streams Remove Duplicate Letter Asked 4 years, 10 months ago Modified 1 year, 11 months ago Viewed 11k times Apr 13, 2017 · Ways to remove duplicate elements from Arrays: Using List implemented classes Using Set implemented classes Using combination of both List & Set implemented classes Without using any collection classes Using Java 8 Streams Let’s discuss one-by-one in detail with example/explanation Jan 14, 2022 · This post will discuss how to remove duplicates from a list in Java without destroying the original ordering of the list elements. Is there any other way that can do something like: Jun 12, 2022 · One of the ways to filter out duplicated elements from the source list is by generating an intermediate Map<Integer,Boolean> where the key would be the element itself and the value would denote whether a particular key has duplicates in the source list. We will use a List to provide Stream of items. For custom objects, ensure that the equals() and hashCode() methods are implemented to correctly identify duplicates. Basically just using Dec 6, 2024 · Handling duplicate elements in ArrayLists is a common task, whether for data cleanup, ensuring data integrity, or simply meeting specific application requirements. Hence the solution can be achieved with the help of a Set. New list with unique values" Apr 16, 2015 · Closed 6 years ago. Mar 11, 2018 · Practically I know ways to reduce duplicate trought distinct(), or assign List to Set, but I have a little different issue. Aug 24, 2017 · Here we don't want to change the original list that' why I am making a duplicate here. "; Jul 12, 2025 · There are many methods to find duplicate elements in a Stream: Using Set: Since Set has the property that it cannot contain any duplicate element. I have seen posts removing duplicate strings form arraylist of string. May 2, 2022 · I'm trying to figure out how to write a stream in Java 8 that removes duplicate records based on a property and a condition, for example: +----+------------------+--------------+ Oct 5, 2023 · To remove duplicates from an ArrayList in Java, you can iterate through the list and add elements to a new ArrayList if they haven't been added before. System. Stream distinct () method. (For a list with N customers, you will need to perform N*(N-1)/2 comparisons in the worst case; i. Mar 13, 2010 · You can add the list into a HashSet and then again convert that hashset into list to remove the duplicates. ) For a more efficient solution you could use a HashSet to do the duplicate checking. Approach: Get the stream of elements in which the duplicates are to be found. The easiest way to remove repeated elements is to add the contents to a Set (which will not allow duplicates) and then add the Set back to the ArrayList: Set<String> set = new HashSet<>(yourList); yourList. The HashSet class implements the Set interface, backed by a hash table which is actually a HashMap instance. Its in a List. Oct 15, 2008 · If you don't want duplicates in a Collection, you should consider why you're using a Collection that allows duplicates. The distinct () is also a standard method, which means it will return a new Stream without Sep 24, 2021 · Removing duplicates from LinkedList: Using Java 8 Stream method distinct () Using Set approach Using Java 8 Collectors. This is a common tasks to avoid duplicates in the list. List<Order> orderList = new ArrayList<> (); I need to remove the objects having same id Oct 8, 2024 · Luckily, Java provides a variety of ways to remove duplicates from a list quickly and efficiently. equals(Object) of this stream For ordered streams Elegant ways to remove duplicate elements from a Java list using Core Java, Java 8 Streams, LinkedHashSet, and Google Guava with examples. The distinct () method behaves like the distinct clause of SQL, which eliminates duplicate rows from the result set. Nov 9, 2021 · A quick guide to remove the duplicate characters from the string in java and jdk 8. remove(). The program covers simple lists of integers and strings, as well as lists of custom objects. In Java 8, how can I filter a collection using the Stream API by checking the distinctness of a property of each object? For example, I have a list of Person objects and I want to remove people wit Conclusion In Java 8, removing duplicates from an array is simple and efficient with the Stream API. Apr 13, 2021 · I need to remove duplicate objects from a list based on some properties and have distinct values. Java Stream distinct () Method The elements are compared using the equals () method. Introduction: How to Remove Duplicates from a Collection in Java Managing duplicates in collections is a common problem in Java programming. You can use the Stream. Whether you’re dealing with a list of integers, strings, or custom objects, the Stream API provides a straightforward way to … Java 8 – Remove Duplicates Mar 7, 2025 · Learn different ways of extracting duplicate elements from a List in Java. Java 8 Program: Remove Duplicate Elements from a List using Java 8 StreamsLearn how to remove duplicate elements from a list using Java 8 Streams in this sho May 9, 2025 · Explore how to implement a lambda expression in Java to remove duplicates from a list of integers. It is a List from the object Blog that looks like this: public class Blog { private String title; private String author; private String u Mar 2, 2024 · In Java 8, the distinct() method is used to eliminate duplicate elements from a stream. sort method Initialize a variable j, to keep track of the last index of unique elements. We will see first using plain Java and then Java 8 Lambda-based solution. Dec 6, 2024 · We can remove duplicate element in an array by 2 ways: using temporary array or using separate index. Luckily, Java offers several efficient techniques for eliminating Jul 11, 2025 · Below are the various methods to remove repeated elements an ArrayList in Java: Using a Set: Since Set is a collection which do not includes any duplicate elements. iterator() to iterate the list once, and on each iteration, iterate it again to check if there are duplicates. The class also offers constant Dec 6, 2024 · We can remove duplicate element in an array by 2 ways: using temporary array or using separate index. To keep ordering you should iterate on the existing list and remove an element only if it's a duplicate (which can be done using a set to check if an element Jun 28, 2019 · Remove duplicates from a list of objects based multiple attributes in Java 8 Asked 5 years, 10 months ago Modified 11 months ago Viewed 6k times Nov 16, 2024 · Given an array, the task is to remove the duplicate elements from an array. Sometimes it may have duplicates. For example: // Duplicates are {1, 4} List<Integer> numbers = Arrays. Jul 31, 2017 · The distinct () function can be used to removed duplicates using a natural comparison, for that first override equals () and hashCode () method in Person class. Feb 26, 2021 · In this article, we will discuss how to remove duplicate element/objects from ArrayList along with various examples. Apr 28, 2021 · I am trying to remove duplicates from a list of Student Objects based on multiple properties while preserving the order,As shown below i have list of student objects where we have multiple students Jan 13, 2015 · java string java-8 java-stream edited Dec 30, 2016 at 2:41 dimo414 49k 19 165 269 Nov 21, 2020 · Read more on Java 8 Stream API In other words, how to remove the duplicates from list or collection using java 8 streams. It’s useful in removing duplicate elements from the collection before processing them. Java 8 Stream – distinct () method Stream’s distinct () method returns a stream consisting of the distinct elements according to Object. Apr 21, 2011 · You can use an O (n^2) solution: Use list. Learn to remove duplicate elements from a List in Java using Collection. We know that a set doesn't allow any duplicate elements. Original list with duplicate values :\n"); System. Whether you’re working with a List, Set, or any other collection, removing duplicates is essential for ensuring data integrity, improving performance, and simplifying operations. I need to remove duplicates from an ArrayList of String irrespective of cases. Learn how to efficiently remove duplicates from a Java 8 List of objects using multiple attributes with streams and collectors. Aug 16, 2022 · We can remove duplicates from a List in Java in the following ways: By converting the List into a Set Using Java 8 Streams Remove duplicates from a List in Java by converting the List into a Set A Set is a Collection that cannot contain duplicate elements. public static int removeDuplicates(List<String> duplicateList){ Nov 19, 2024 · Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more. Using set () We can use set () to remove duplicates from the list. removeIf (), HashSet, LinkedHashSet, and Stream APIs. com Dec 11, 2018 · Given an ArrayList with duplicate values, the task is to remove the duplicate values from this ArrayList in Java. Now convert the Set back to ArrayList. In this article, you will learn how to remove duplicate elements from an ArrayList using different methods in Java. This guide will cover several approaches to remove duplicates, explain how they work, and provide examples to demonstrate their functionality. Is there any other way that can do something like: Jan 8, 2024 · Learn a few ways to remove duplicate values from a Java HashMap. It returns a new stream containing distinct elements based on their natural ordering or the result of Nov 6, 2018 · This code removes duplicates from the original list, but I want to extract the duplicates from the original list -> not removing them (this package name is just part of another project): Given: a In this example, we will learn to convert the duplicate element from the ArrayList in Java. Required fields are marked *. May 23, 2019 · Java program to find out unique and duplicates values as separate list from two lists (ArrayList). Create another ArrayList. This table compares the different approaches and their advantages. when there are no duplicates. 1. toSet ()) method which results into duplicate list FindDuplicatesUsingDistinctMethod. How to remove custom objects from ArrayList. Mar 3, 2013 · Im trying to work on an assignment question for my intro java course where we are supposed to remove duplicate items from a list without using sets or the . Dec 28, 2014 · I am trying to list out duplicate elements in an integer list using Streams of JDK 8. toList(). In this blog, we’ll walk through the most effective ways to remove all duplicates from a list in Java. Find the solution and practice exercises to enhance your Java programming skills. Jul 28, 2023 · Removing Duplicates by assigning List to TreeSet : Preparing a list containing duplicate Department objects, and remove those duplicate departments using Java8 stream. When we convert a List into a Set, all duplicates will be removed. for eq: List list = Lists. How to solve smart way below problem in JAVA 8 using stream or may be St Nov 28, 2018 · I have a Java bean, like class EmployeeContract { Long id; Date date; getter/setter } If a have a long list of these, in which we have duplicates by id but with different date, such a I have to remove duplicated objects in a List. The following list describes some of the most commonly used approaches: Aug 28, 2024 · Introduction Java 8 introduced the Stream API, offering a powerful and efficient way to process collections of data in a functional and declarative style. I am trying to remove duplicates from a List of objects based on some property. Feb 12, 2022 · For finding duplicates, iterate through original List and remove elements by comparing elements in unique list and store into new Set using collect (Collectors. This is true in every answer posted so far. Sets only allow unique elements, so by adding the list to a Set, duplicates will automatically be removed. Since Set doesn't contain duplicate elements, it will have only unique elements. Dec 27, 2023 · How to remove duplicates from a List in Java There are several ways to find duplicates in a Java List, array or other collection class. If the stream is ordered, the encounter order is May 14, 2021 · Remove duplicate elements across multiple lists java 8 Asked 4 years ago Modified 4 years ago Viewed 2k times May 27, 2019 · A Quick Guide to how to remove duplicate objects from ArrayList. Mar 31, 2023 · To remove duplicates from a list in Java, you can use a Set data structure. Traverse through the first arraylist and store the first appearance of each element into the second arraylist using contains () method. Java offers several ways to handle this task, each with its own trade-offs regarding readability, performance, and May 7, 2025 · Java Stream: Exercises, Practice, Solution - Learn how to remove duplicate elements from a list using Java streams. Example program are demonstrated with Set, a new List with contains() method and Java 8 Streams. hashCode(); } It is also worth noting that this is not an efficient way to remove duplicates if the list is large. Let’s discuss one-by-one in detail with example/explanation. How do I remove second duplicate (or multiple) while keeping first one? For example, keep 3-furniture and remove List<Map<String, Object>> apptlist = jdbcTemplate. contains() method. stream(). toString ()); Here I got a list. This Java 8 program demonstrates how to remove duplicate elements from a list using streams and the distinct() method. To remove the duplicate element from array, the array must be in sorted order. e. Nov 9, 2024 · Learn quick and easy ways to remove duplicates from lists in Java, including how to remove duplicate objects based on a specific property. But what about finding the duplicated elements? May 7, 2025 · Starting point: public class Employee { private String id; private String name; private String age; } I have a list of Employee: List<Employee> employee; Employee examples from Aug 16, 2024 · java 8. addAll(set); Of course, this destroys the ordering In Java 8, you can leverage the Stream API along with a distinct filter to remove duplicates from a list of objects based on a specified property, such as an ID. Use the distinct() method to remove duplicates. Explore techniques and examples to effectively manage duplicates. See full list on baeldung. Let us see the example programs using plain java and java 8 stream api lambda expressions. The simplest method to remove duplicates from an array is using a Set, which automatically eliminates duplicates. distinct () method eliminates/removes duplicate from Original Arrays and store into new Arrays using toArray (String []::new) method which results into unique elements in an Arrays For finding duplicates, Create a new List using original ArraysIterate through new List and remove elements by comparing elements in unique Arrays Elements remaining in the Feb 17, 2023 · In this article, we will discuss how to find and count duplicate values in a Map or HashMap Find & Count duplicate values in a Read More When not to Use Parallel Stream?Remove Duplicates from a list/array of Numbers. If there are - call iterator. If we can change the original list then simply don't store in duplicate, but remove from original list looping over set. One common task when working with collections is removing duplicate elements. distinct(); distinct() above wont do any help as it works on equals method which will return false. May 7, 2025 · Java Stream: Exercises, Practice, Solution - Learn how to remove duplicate elements from a list using Java streams. Aug 28, 2024 · Removing duplicates from a list in Java 8 is simple and efficient with lambda expressions and the Stream API. Mar 3, 2021 · As we know that the HashSet contains only unique elements, ie no duplicate entries are allowed, and since our aim is to remove the duplicate entries from the collection, so for removing all the duplicate entries from the collection, we will use HashSet. Collect the distinct elements into a new ArrayList using Collectors. Jul 17, 2022 · Java 8 examples to count the duplicates in a stream and remove the duplicates from the stream. How about this one, only for the sorted Array of numbers, to print the Array without duplicates, without using Set or other Collections, just an Array: public static int[] removeDuplicates(int[] array) { Apr 12, 2021 · How to remove duplicate from list of object in java using stream API Asked 4 years, 2 months ago Modified 4 years, 2 months ago Viewed 2k times Sep 5, 2024 · To remove dupliates from ArrayList, we can convert it into Set. Examples: Get the ArrayList with duplicate values. util. In that list duplicate maps are showing. Aug 6, 2020 · Let's see how to remove duplicates from arraylist in java and there are some methods of arraylist remove duplicate from the arraylist. There are a variety of functions in Java that simplify that process. brhkrathzunbxejwypfdscimrtqmrtwcctqoydhytkuomu