Exception in Thread AWT Event Queue 0 Java.lang.nullpointerexception

异常：Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: com.wsb.pub ...

用netbeans 6.5时，遇到一个问题，没有解决。 Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: com.wsb.pub.Item cannot be cast to java ...

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