Mark sends us a very simple Java function which has the job of parsing an integer from a string. Now, you might say, "But Java has a built in for that, Integer.parseInt," and have I got good news for you: they actually used it. It's just everything else they did wrong.

private int makeInteger(String s)
{
  int i=0;
  try
  {
    Integer.parseInt(s);
  }
  catch (NumberFormatException e)
  {
    i=0;
    return i;
  }
  i=Integer.parseInt(s);
  return i;
}

Frank inherited some code that reads URLs from a file, and puts them into a collection. This is a delightfully simple task. What could go wrong?

static String[]  readFile(String filename) {
    String record = null;
    Vector vURLs = new Vector();
    int recCnt = 0;

    try {
        FileReader fr = new FileReader(filename);
        BufferedReader br = new BufferedReader(fr);

        record = new String();

        while ((record = br.readLine()) != null) {
            vURLs.add(new String(record));
            //System.out.println(recCnt + ": " + vURLs.get(recCnt));
            recCnt++;
        }
    } catch (IOException e) {
        // catch possible io errors from readLine()
        System.out.println("IOException error reading " + filename + " in readURLs()!\n");
        e.printStackTrace();
    }

    System.out.println("Reading URLs ...\n");

    int arrCnt = 0;
    String[] sURLs = new String[vURLs.size()];
    Enumeration eURLs = vURLs.elements();

    for (Enumeration e = vURLs.elements() ; e.hasMoreElements() ;) {
        sURLs[arrCnt] = (String)e.nextElement();
        System.out.println(arrCnt + ": " + sURLs[arrCnt]);
        arrCnt++;
    }

    if (recCnt != arrCnt++) {
        System.out.println("WARNING: The number of URLs in the input file does not match the number of URLs in the array!\n\n");
    }

    return sURLs;
} // end of readFile()

Andre has inherited a rather antique ASP .Net WebForms application. It's a large one, with many pages in it, but they all follow a certain pattern. Let's see if you can spot it.

protected void btnSearch_Click(object sender, EventArgs e)
{
    ArrayList paramsRel = new ArrayList();
    paramsRel["Name"] = txtNome.Text;
    paramsRel["Date"] = txtDate.Text;
    Session["paramsRel"] = paramsRel;
   
    List<Client> clients = Controller.FindClients();
    //Some other code
}

Frequently in programming, we can make a tradeoff: use less (or more) CPU in exchange for using more (or less) memory. Lookup tables are a great example: use a big pile of memory to turn complicated calculations into O(1) operations.

So, for example, implementing itoa, the C library function for turning an integer into a character array (aka, a string), you could maybe make it more efficient using a lookup table.