Thread: unsafe operations note??

import java.util.*;
 
public class iterates {
 
    private ArrayList<String> arrayOfString = new ArrayList();
    private String input = "hui hello { q...} qdf qkfh youu";
    private int n = 0;
 
    public static void main(String[] args) {
        iterates h = new iterates();
        h.studyString();
    }
 
    public void studyString() {
        String originalText = "Hello ther{e oops)eee";
        arrayOfString = toArray(originalText);
        Iterator bitch = arrayOfString.iterator();
 
        while (bitch.hasNext()) {
            if (bitch.next().equals('{') || bitch.next().equals('}')) {
                int i = arrayOfString.indexOf(bitch.next());
                arrayOfString.add(i + 1, "<br>");
            }
        }
 
    }
 
    public ArrayList<String> toArray(String input) {
        StringTokenizer pieces = new StringTokenizer(input);
 
 
        while (n <= pieces.countTokens()) {
            arrayOfString.add(n, pieces.nextToken());
        }
        n++;
 
        return arrayOfString;
    }
}

Upon compiling this, I get the note "iterates.java uses unchecked or unsafe operations"; "Recompile with -Xlint: unchecked for details". How can I resolve this?

Note, I am trying to convert a random string (the code here has been slightly adjusted - this is in fact a stub of a class) to an arrayList<String>. If you have a better idea as to how I should do this, please let me know!

Thanks!