title: Birt Global Integer
body: <p>I have a Birt Report which read some stuff from a database.
  After that i want to increment a global Integer for every Detailrow that is loaded.
  So far i have initialized a global Integer with the following lines:</p>
  
  <pre><code>importPackage(Packages.java.lang);
  reportContext.setPersistentGlobalVariable("minTotalPlus", new Integer(0));
  </code></pre>
  
  <p>After that i added the following line into a field in my detail row:</p>
  
  <pre><code>reportContext.setGlobalVariable("minTotalPlus",  new Integer reportContext.getGlobalVariable("minTotalPlus")) + 1);
  </code></pre>
  
  <p>When i preview the report i get an "java.lang.NumberFormatException: null" which means that the global variable is null. Why is that so? How could I fix that?</p>