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Runtime Error in Program for Unknown Reasons

Jacob Steingart
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Joined: Mar 28, 2008
Posts: 63
I typed this up myself from Head First Java. I keep getting a NullPointerException that says the following:

Exception in thread "main" java.lang.NullPointerException
at QuizCardPlayer.go(QuizCardPlayer.java:27)
at QuizCardPlayer.main(QuizCardPlayer.java:19)

I didn't see anything blatently wrong with the code I had written, and the problem appeared to be in my first two methods, but it starts up the same way as some other programs of mine that work fine. Here is the code, cut and pasted fresh from jGrasp.



If someone could scan this over or if they know that I made some stupid mistake (I haven't done GUI in awhile, I'm still getting back into the swing of things, no pun intended) I would be immensley thankful.
[ June 04, 2008: Message edited by: Rob Prime ]

I never know what to put in my signature...
Ernest Friedman-Hill
author and iconoclast
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Joined: Jul 08, 2003
Posts: 24187
    
  34

The top line from the stack trace in the error message

at QuizCardPlayer.go(QuizCardPlayer.java:27)

means that the error happens at line 27 of this file. Use your editor to figure out what line that is. A NullPointerException on a particular line always means that something to the left of a dot ('.') or left-brace ('[') is null. Find out what variable on that line might be null, then try to figure out where its value should have been set, and you'll have solved the problem.


[Jess in Action][AskingGoodQuestions]
Jacob Steingart
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Joined: Mar 28, 2008
Posts: 63
Aha! I was stupid and forgot to declare the JTextArea... now it works!
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Runtime Error in Program for Unknown Reasons