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PONull pointer exception error that I am having trouble figuring out?
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2011-11-03T20:46:33.900
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2011-11-05T11:36:36.140
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2011-11-05T11:36:36.140
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I can't figure out how to fix my null pointer. My holder (Holder Pattern class) is undefined - I'm not sure how to fix it. I am still pretty new to programming. Thanks for any ideas on how to go about fixing this! <pre><code>public Goose (JPanel container, GooseBehavior behavior, BehaviorHolder holder) { super(container); _holder = holder; double rnd = Math.random(); //local variable to create random angle //System.out.println(rnd); this.setRotation(rnd);//sets the rotation angle to a random angle this.setSize(25, 20); //sets size this.setFillColor(java.awt.Color.RED); //sets color this.setWrapping(true); //sets wrapping to true _gooseBehavior = behavior; //stores _gooseehavior _gooseBehavior = _holder.getBehavior(); } public void react() { _gooseBehavior.stop(); //tells the current _gooseBehavior to stop _holder.getBehavior(); //gets the stored behavior from the holder _gooseBehavior = _holder.getBehavior(); //sets the new value to one stored in holder _gooseBehavior.setTarget(this); //sets the target on goose _gooseBehavior.start(); //starts the behavior } </code></pre> Stacktrace: <pre><code>Exception in thread "main" java.lang.NullPointerException at Animal.Goose.<init>(Bee.java:26) at Animal.DrawingPanel.<init>(DrawingPanel.java:30) at Animal.ControlPanel.<init>(ControlPanel.java:27) at Animal.App.<init>(App.java:28) at Animal.App.main(App.java:39) </code></pre> Here's the code where I instantiate BehaviorHolder in my Control Panel (top level object), and then I just have it stored in my drawingPanel, Goose class, and BehaviorButtons so that its associated with the three. <pre><code>public ControlPanel() { super(); this.setLayout(new BorderLayout());//sets a new BorderLayout _drawingPanel = new DrawingPanel(_holder); _moveRandomly = new MoveBehavior(); _doNothing = new StopBehavior(); _kingGoose = new FollowBehavior(_kingGoose); _holder = new BehaviorHolder(_moveBehavior); </code></pre>
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<java><swing>
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Null pointer exception error that I am having trouble figuring out?
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