title: StringTokenizer with .txt file when no value in the line
body: <p>I have a programming homework to do and our teacher wants us to use the <code>StringTokenizer</code>.
  We have a txt file with the <code>matricule \t name \t first name \t Grade1 \t Grade2 \t Grade3 \t Grade 4</code> on one line. I want my code to return "0" when the StringTokenizer hit a token with nothing. I am not allowed to use the split function. </p>
  
  <p>here is an example of date : </p>
  
  <pre><code>00000005    manque tp1  donne 90        40  100 100
  </code></pre>
  
  <p>Program</p>
  
  <pre><code>String line;
          while ((ligne = reader.readLine()) != null) {
              StringTokenizer var = new StringTokenizer(ligne, "\t");
              String matricule = var.nextToken();
              String nom = var.nextToken();
              String prenom = var.nextToken();
              double noteTP1 = Double.parseDouble(var.nextToken());
              double noteTP2 = Double.parseDouble(var.nextToken());
              double noteIntra = Double.parseDouble(var.nextToken());
              double noteFinal = Double.parseDouble(var.nextToken());
  </code></pre>