remove duplicate string collection 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 str1 = "ABCDABCD";
2String result1 = "";
3
4for (int a = 0; a <= str1.length()-1; a++) {
5if (result1.contains("" + str1.charAt(a))) { 
6// charAt methodda you provide index number ve sana character olarak donuyor,
7// If the string result does not contains str.CharAt(i), 
8// then we concate it to the result. if it does we will not
9   continue;
10}
11result1 += str1.charAt(a);
12}
13System.out.println(result1);

1String str2 = "ABABABCDEF";// ABCDEF
2        String[] arr2 = str2.split("");
3str2 = new LinkedHashSet<>(Arrays.asList(arr2)).toString().replace(", ", "");
4        System.out.println(str2); // ABCDEF