Do you want to identify duplicates elements from Java List?
The method add of set returns a boolean whether a value already exists (true if it does not exist, false if it already exists, see Set documentation).
So just iterate through all the values.
Java Code:
package com.crunchify.tutorials;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
public class CrunchifyFindDuplicateInList {
/**
* @author Crunchify.com
*/
public static void main(String[] args) {
List<String> list = new LinkedList<String>();
for (int i = 0; i < 10; i++) {
list.add(String.valueOf(i));
}
for (int i = 0; i < 5; i++) {
list.add(String.valueOf(i));
}
System.out.println("My List : " + list);
System.out.println("\nHere are the duplicate elements from list : " + findDuplicates(list));
}
public static Set<String> findDuplicates(List<String> listContainingDuplicates) {
final Set<String> setToReturn = new HashSet<String>();
final Set<String> set1 = new HashSet<String>();
for (String yourInt : listContainingDuplicates) {
if (!set1.add(yourInt)) {
setToReturn.add(yourInt);
}
}
return setToReturn;
}
}
Output:
My List : [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4] Here are the duplicate elements from list : [3, 2, 1, 0, 4]