traverse strings

public class StringTraversal {
    public static void main(String[] args) {
        String s="Hello world!";
        for(int i=0; i<s.length(); i++){
            String ch=s.substring(i,i+1);
            System.out.print(ch);
        }
        System.out.println("\nDONE!");

        for(int i=s.length()-1; i>=0; i--){
            String ch=s.substring(i,i+1);
            System.out.print(ch);
        }
        System.out.println("\nDONE!");

        for(int i=0; i<s.length(); i++){
            String ch=s.substring(s.length()-1-i,s.length()-i);
            System.out.print(ch);
        }
        System.out.println("\nDONE!");
    }
}