remove duplicates from string in java

import java.util.*;

public class RemoveDuplicatesFromArrayList {

    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(1,2,2,2,3,5);

        System.out.println(numbers);

        Set<Integer> hashSet = new LinkedHashSet(numbers);
        ArrayList<Integer> removedDuplicates = new ArrayList(hashSet);

        System.out.println(removedDuplicates);
    }
}

String fullString = "lol lol";
String[] words = fullString.split("\\W+");
StringBuilder stringBuilder = new StringBuilder();
Set<String> wordsHashSet = new HashSet<>();

for (String word : words) {
    if (wordsHashSet.contains(word.toLowerCase())) continue;
    wordsHashSet.add(word.toLowerCase());
    stringBuilder.append(word).append(" ");
}
String nonDuplicateString = stringBuilder.toString().trim();

int i,j;
StringBuffer str=new StringBuffer();
Scanner in = new Scanner(System.in);
System.out.print("Enter string: ");
str.append(in.nextLine());

for (i=0;i<str.length()-1;i++){
    for (j=i+1;j<str.length();j++){
        if (str.charAt(i)==str.charAt(j))
            str.deleteCharAt(j);
    }
}
System.out.println("Removed non-unique symbols: " + str);