java arraylist to string

1ArrayList<String> al = new ArrayList<String>();
2      al.add("Hello");
3      al.add("Wor");
4      al.add("ld");
5      StringBuffer sb = new StringBuffer();
6      
7      for (String s : al) {
8         sb.append(s);
9         sb.append(" ");
10      }
11      String str = sb.toString();
12      System.out.println(str);//"Hello wor ld" 

1new ArrayList( Arrays.asList( new String[]{"abc", "def"} ) );

1String listString = String.join(", ", list); //Java 8 or later