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In this quick tutorial, I show you how to find duplicates in List in Java. We will see first using plain Java and then Java 8 Lambda-based solution.
Remove Duplicates from a List Using Plain Java
Removing the duplicate elements from a List with the standard Java Collections Framework is done easily through a Set:
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
/**
* Remove Duplicates from a List Using Java
* @author Ramesh Fadatare
*
*/
public class FindDuplicatesInList {
public static void main(String[] args) {
List <Integer> listWithDuplicates = Arrays.asList(0, 1, 2, 3, 0, 0);
List <Integer> listWithoutDuplicates = new ArrayList <> (
new HashSet <> (listWithDuplicates));
listWithoutDuplicates.forEach(element -> System.out.println(element));
}
}
Output:
0
1
2
3Remove Duplicates from a List Using Java 8 Lambdas
Let's look at a new solution, using Lambdas in Java 8; we're going to use the distinct() method from the Stream API which returns a stream consisting of distinct elements based on the result returned by equals() method:
package net.javaguides.jackson;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
/**
* Remove Duplicates from a List Using Java
* @author Ramesh Fadatare
*
*/
public class FindDuplicatesInList {
public static void main(String[] args) {
List <Integer> listWithDuplicates = Arrays.asList(0, 1, 2, 3, 0, 0);
List <Integer> listWithoutDuplicates = listWithDuplicates.stream()
.distinct()
.collect(Collectors.toList());
listWithoutDuplicates.forEach(element -> System.out.println(element));
}
}
Output:
0
1
2
3
Title misleading - does not actually find the duplicates
ReplyDeleteI don't see any issues. Can you provide more details to identify the issue?
Delete