string remove duplicate method in java

1public static void main(String[] args) {
2
3        String result = removeDup("AAABBBCCC");
4        System.out.println(result); // ABC
5
6public static  String  removeDup( String  str) {
7        String result = "";
8        for (int i = 0; i < str.length(); i++)
9            if (!result.contains("" + str.charAt(i)))
10                result += "" + str.charAt(i);
11        return result;
12    }
13}

1import java.util.*;
2
3public class RemoveDuplicatesFromArrayList {
4
5    public static void main(String[] args) {
6        List<Integer> numbers = Arrays.asList(1,2,2,2,3,5);
7
8        System.out.println(numbers);
9
10        Set<Integer> hashSet = new LinkedHashSet(numbers);
11        ArrayList<Integer> removedDuplicates = new ArrayList(hashSet);
12
13        System.out.println(removedDuplicates);
14    }
15}
16

1String fullString = "lol lol";
2String[] words = fullString.split("\\W+");
3StringBuilder stringBuilder = new StringBuilder();
4Set<String> wordsHashSet = new HashSet<>();
5
6for (String word : words) {
7    if (wordsHashSet.contains(word.toLowerCase())) continue;
8    wordsHashSet.add(word.toLowerCase());
9    stringBuilder.append(word).append(" ");
10}
11String nonDuplicateString = stringBuilder.toString().trim();

1public static <T> ArrayList<T> removeDuplicates(ArrayList<T> list){
2  Set<T> set = new LinkedHashSet<>(list);
3  return new ArrayList<T>(set);
4}

1List<Integer>numbers = Arrays.asList(1,2,2,2,3,5); // [1, 2, 3, 5]
2System.out.println(numbers);
3
4Set<Integer> hashSet = new LinkedHashSet(numbers);
5ArrayList<Integer> removedDuplicates = new ArrayList(hashSet);
6System.out.println(removedDuplicates); // [1, 2, 3, 5]