[Repast-interest] problem with running predator prey model in repast

[vishal a. <vis...@gm...>]

hii all.


i am a newbie for repast smphony.
 i have been trying to run the predator prey model using java code from the
GETTING STARTED tutorial pdf...but while running the project i am getting
the java.lang.nullpointerException. i am using *Eclipse SDKe  Version: 3.4.1
*
**
the actual error shown in the error log of runtime window is as follows:



2009/12/07 16:28:50,620: Error while initializing simulation
java.lang.NullPointerException
 at predatorprey.Grass.<init>(Grass.java:39)
 at predatorprey.PPContextCreator.build(PPContextCreator.java:80)
 at
repast.simphony.dataLoader.engine.ClassNameContextBuilder.build(ClassNameContextBuilder.java:39)
 at
repast.simphony.dataLoader.engine.DataLoaderControllerAction.runInitialize(DataLoaderControllerAction.java:51)
 at
repast.simphony.engine.controller.DefaultController$2.visit(DefaultController.java:171)
 at
repast.simphony.engine.controller.DefaultController$2.visit(DefaultController.java:1)
 at
repast.simphony.util.collections.NaryTree.preOrderTraverals(NaryTree.java:287)
 at
repast.simphony.util.collections.NaryTree.preOrderTraverals(NaryTree.java:290)
 at
repast.simphony.util.collections.NaryTree.preOrderTraverals(NaryTree.java:290)
 at
repast.simphony.util.collections.NaryTree.preOrderTraversal(NaryTree.java:283)
 at
repast.simphony.engine.controller.DefaultController.runInitialize(DefaultController.java:169)
 at
repast.simphony.engine.controller.DefaultController.runInitialize(DefaultController.java:324)
 at repast.simphony.ui.RSApplication.initSim(RSApplication.java:134)
 at repast.simphony.ui.RSApplication.start(RSApplication.java:158)
 at repast.simphony.ui.action.StartRun.actionPerformed(StartRun.java:17)
 at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
 at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
 at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
 at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
 at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
 at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
 at java.awt.Component.processMouseEvent(Unknown Source)
 at javax.swing.JComponent.processMouseEvent(Unknown Source)
 at java.awt.Component.processEvent(Unknown Source)
 at java.awt.Container.processEvent(Unknown Source)
 at java.awt.Component.dispatchEventImpl(Unknown Source)
 at java.awt.Container.dispatchEventImpl(Unknown Source)
 at java.awt.Component.dispatchEvent(Unknown Source)
 at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
 at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
 at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
 at java.awt.Container.dispatchEventImpl(Unknown Source)
 at java.awt.Window.dispatchEventImpl(Unknown Source)
 at java.awt.Component.dispatchEvent(Unknown Source)
 at java.awt.EventQueue.dispatchEvent(Unknown Source)
 at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
 at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
 at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
 at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
 at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
 at java.awt.EventDispatchThread.run(Unknown Source)


i am aware that it is not a new problem but still i was not able to get any
solution from the net...please help me out on this.

thanks.

warm regards
vishal.