[java] Print the stack trace of an exception

I have created a method that helps with getting the stackTrace:

private static String getStackTrace(Exception ex) {
    StringBuffer sb = new StringBuffer(500);
    StackTraceElement[] st = ex.getStackTrace();
    sb.append(ex.getClass().getName() + ": " + ex.getMessage() + "\n");
    for (int i = 0; i < st.length; i++) {
      sb.append("\t at " + st[i].toString() + "\n");
    }
    return sb.toString();
}