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Thread: Java Program Help

  1. #1
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    Default Java Program Help

    I am a novice Java coder. And I am having trouble finding the problem when I start up the program and click the "list files" button, and there are more than 37 files or more to load. It crashes and gives me a null pointer exception at line 77 in the Displays class. Any help would be greatly apreciated. I am still in the process of writing it. So any half finished code is supposed to be that way.

    The source code is here:

    https://www.dropbox.com/s/1mkertitu5qbj77/My%20Code.zip


  2. #2
    Senior Member PhHein's Avatar
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    Default Re: Java Program Help

    Hi,

    nobody will bothered to download your sources, or is behind a firewall and cannot access it. Post a SSCCE.

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    Super Moderator Norm's Avatar
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    Default Re: Java Program Help

    gives me a null pointer exception at line 77
    There is a variable with a null value on line 77. Look at line 77 in the your source and see what variable is null. Then backtrack in the code to see why that variable does not have a valid value.
    If you can not tell which variable it is, add a println just before line 77 and print out the values of all the variables on that line.
    If you don't understand my answer, don't ignore it, ask a question.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Java Program Help

    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Java Program Help

    Quote Originally Posted by Norm View Post
    There is a variable with a null value on line 77. Look at line 77 in the your source and see what variable is null. Then backtrack in the code to see why that variable does not have a valid value.
    If you can not tell which variable it is, add a println just before line 77 and print out the values of all the variables on that line.
    I am adding a panel from an array of panels to a frame and says null pointer exception.

    frame.add(panel[0]);

    and at this line it says null pointer exception. I even checked to see if the panel array wasn't initialized correctly. But the length is 2 so I know it was initialized correctly. But it still doesn't work.

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Java Program Help

    What are the values of frame and panel[0]?

    The slots in an array of objects are initially null.
    If you don't understand my answer, don't ignore it, ask a question.

  7. #7
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    Default Re: Java Program Help

    *facepalm* Something as simple as initializing the points in an array stopped me. Thank you.

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