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NullPointerExcpetion Help

Jack O'Herrer
Greenhorn

Joined: Feb 21, 2008
Posts: 2
Hey Everyone, I'm hoping that one of you can help me with a problem I'm having. The code I'm trying to run is compiling fine, but I'm getting a NullPointerException error when I'm actually trying to run it. What I think is happening is the stack is for some reason being initialized with a null value at the beginning.

Any help would be greatly appreciated. Heres the code


[ February 21, 2008: Message edited by: Jack O'Herrer ]
[ February 21, 2008: Message edited by: Jack O'Herrer ]
Garrett Rowe
Ranch Hand

Joined: Jan 17, 2006
Posts: 1296


I haven't read through all your code, but you do have a problem here. The String you are assigning in your constructor isn't the same as the String you declare as an instance variable. Can you figure out why?


Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them. - Laurence J. Peter
Jack O'Herrer
Greenhorn

Joined: Feb 21, 2008
Posts: 2
Aha! Thanks, I didn't realize that I reinitialized the string variable.

Now that thats fixed, I'm having problems with writing to the output file. Even when I try to hardcode the line

outFile.println("This is a test");

I'm getting nothing in the file P5.txt

Thanks again for the help
Garrett Rowe
Ranch Hand

Joined: Jan 17, 2006
Posts: 1296
Try closing your PrintWriter when you are done writing, aside from that just being a good habit to get into, it also automatically calls the flush() method to ensure all the data in the buffer gets written to the output file.
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 39084
    
  23
Another suggestion: you are not implementing the equals() method correctly; it ought to take Object as a parameter type.
Please do a search for equals(); it is discussed frequently on these boards.
 
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subject: NullPointerExcpetion Help