Join ArrayList in java. Combines all the elements into a string separated the `delimiter`.

Join ArrayList in java

/**
* Combines all the elements into a string seperated the `delimiter`.
* Same as `Array.prototype.join()` in Javascript.
* @example 
ArrayList<String> x = new ArrayList<String>();
 
x.add("1");
x.add("2");
 
joinArrayListString(x, ",").equals("1,2") == true;
*/
public String joinArrayListString(ArrayList<String> r, String delimiter) {
  if(r == null || r.size() == 0 ){
  	return "";
	}
	StringBuffer sb = new StringBuffer();
	int i, len = r.size() - 1;
	for (i = 0; i < len; i++){
		sb.append(r.get(i) + delimiter);
	}
	return sb.toString() + r.get(i);
}