title: Call "java -jar MyFile.jar" with additional classpath option
body: <p>I created a jar file containing all my compiled stuff. Additionally my ant build script copies the required libs into a subfolder "libs". The structure looks like this:</p>
  
  <pre><code>MyProgram.jar
  libs/
  </code></pre>
  
  <p>So when I try to run my program now I get the following error:</p>
  
  <pre><code>java -cp ".:/home/user/java/MyProgram/jar/libs" -jar MyProgram.jar
  java.lang.ClassNotFoundException: org.postgresql.Driver
      at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
      at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:186)
      at database.PostgresQL.getConnection(PostgresQL.java:38)
      at recommender.dao.Creative2IdxDAO.createCreatives2Idx(Creative2IdxDAO.java:19)
      at main.Main.calculateCorrelationMatrix(Main.java:51)
      at main.Main.main(Main.java:28)
  java.lang.NullPointerException
      at recommender.dao.Creative2IdxDAO.createCreatives2Idx(Creative2IdxDAO.java:25)
      at main.Main.calculateCorrelationMatrix(Main.java:51)
      at main.Main.main(Main.java:28)
  </code></pre>
  
  <p>Why does this happen?</p>