hi, i need help with a couple of javabats.

1) http://javabat.com/prob?id=String3 .sumNumbers

Code:
public int sumNumbers(String str) {
  
  String retString = "";
  String m = "";
  int temp = 0;
  
  for (int k = 0; k < str.length(); k++)
    {
      char c = str.charAt(k);
      if (Character.isLetterOrDigit(c))
	{
...