Java / List and its implementations
Java collections: How do I identify duplicate elements in a List?
Using HashSet implementation which doesn't allow duplicates can be used to identify the elements that are duplicate at the List. Set has a method add() that return boolean value true if the element already exists else returns false which can be used as a tracker to find the duplicate elements as shown below.
import java.util.Arrays; import java.util.HashSet; import java.util.List; import java.util.Set; public class DuplicateElements { public static void main(String[] args) { String[] stringList = { "Javapedia.net", "Javapedia.net", "minim.tk", "weatherman.com" }; List<String> listwithDuplicates = Arrays.asList(stringList); final Set<String> tempSet = new HashSet<>(); final Set<String> duplicateElements = new HashSet<>(); for (String element : listwithDuplicates) { if (!tempSet.add(element)) { duplicateElements.add(element); } } System.out.println(duplicateElements); } }
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