May 23, 2017 · Hash table and linked list implementation of the Map interface, with predictable iteration order. This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries.

Aug 1, 2011 · Use apache commons library class's method org.apache.commons.collections.MapUtils.invertMap(map) and compare the size of actual map and invert map.

Mar 7, 2025 · In this article, we learned about different ways of extracting duplicate elements from a List in Java. We discussed approaches using Set and Map and their corresponding approaches using Stream.

Oct 2, 2018 · You can transfre your list if Map to list of EntrySet. List<Map.Entry<String, String>> entries = fileDataList.stream() .flatMap(e -> e.entrySet().stream()) .collect(toList());

Feb 17, 2023 · In this article, we will discuss how to find and count duplicate values in a Map or HashMap. We will discuss 2 different approaches –. 1. Using Java 8 Stream : System.out.println("1. Original Map Entries :- \n"); System.out.println("\n\n2. Player's percentile & duplicate count :- \n"); System.out.println("\n\n3.

Jul 17, 2017 · Here is different ways to find duplicate objects in list like Find duplicate objects in list using Set ,Find duplicate objects in list using Stream Group by, hash map etc..

Mar 29, 2024 · In this tutorial, we’ll explore different approaches to finding map keys with duplicate values in a Set. In other words, we aim to transform a Map<K, V> to a Map<V, Set<K>>.

Feb 12, 2022 · In this article, we will discuss how to find and count duplicates in a Stream or List in different ways. Let us discuss each one with example and description. 1. Using Stream.distinct () method : System.out.println("1. Original List with duplicates : \n"); System.out.println("\n2. Unique elements : \n"); System.out.println("\n3.

Jan 21, 2019 · In this post, we will learn to find duplicate elements in array in java using Brute Force method, using Sorting method, using HashSet, using HashMap and using Java 8 Streams.

java 8 base solution: List duplicates = list.stream().collect(Collectors.groupingBy(Function.identity())) .entrySet() .stream() .filter(e -> e.getValue().size() > 1) .map(Map.Entry::getKey) .collect(Collectors.toList());