title: Stack in Constructor
body: <pre><code>Card karte;
  Stack &lt;Card&gt; kartenstapel;
  
   public Standard52() {
  
       /** this works*/
       this.karte = new Card(Suit.HEARTS,13);                       
  
       /** this throws a 0-pointer exception when I try to initial*/
  
       this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));
       this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));
       this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));
       this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));
   }
  </code></pre>
  
  <p>Why i get a null pointer exception when i try to inital it. 
  Its more theorie then practice but i do not undersstand my failure maybe some of you can explain me where my mistake is.</p>