[Java]遍历字符串.length(), .charAt()

public class CharAt
{
    public static void main(String[] args)
    {
        String ac = "Hello World";
        //for (int i = 0; i < ac.length(); i++)
        int i = 0;
        //while (i < ac.length())
        
        do {
            System.out.println(ac.charAt(i));
            if (ac.charAt(i) == ‘o‘)
                break;
            i++;
        } while (i < ac.length());
    }
}