java arraylist to string

ArrayList<String> al = new ArrayList<String>();
      al.add("Hello");
      al.add("Wor");
      al.add("ld");
      StringBuffer sb = new StringBuffer();
      
      for (String s : al) {
         sb.append(s);
         sb.append(" ");
      }
      String str = sb.toString();
      System.out.println(str);//"Hello wor ld"