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Thread: I have a NullPointerException error that I dont understand

  1. #1
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    Default I have a NullPointerException error that I dont understand

    I get an error that I cant seem to fix . I have a lot of code, so ask me for each individual class.

    Error:

    Exception in thread "Thread-3" java.lang.NullPointerException
    	at com.riddlekeys.src.gfx.SpriteSheet.crop3(SpriteSheet.java:29)
    	at com.riddlekeys.src.gfx.ImageManager.<init>(ImageManager.java:177)
    	at com.riddlekeys.src.Game.init(Game.java:173)
    	at com.riddlekeys.src.Game.run(Game.java:235)
    	at java.lang.Thread.run(Unknown Source)

    Thanks!

    Luke
    Last edited by LukeR; December 26th, 2013 at 05:10 PM. Reason: I failed xD


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: I have a NullPointerException error that I dont understand

    Exception in thread "Thread-3" java.lang.NullPointerException
    at com.riddlekeys.src.gfx.SpriteSheet.crop3(SpriteShe et.java:29)
    There is a variable with a null value on line 29. Look at line 29 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 29 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.

  3. The Following User Says Thank You to Norm For This Useful Post:

    LukeR (December 14th, 2013)

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    Default Re: I have a NullPointerException error that I dont understand

    Exception in thread "Thread-3" java.lang.NullPointerException
    at com.riddlekeys.src.gfx.SpriteSheet.crop3(SpriteSheet.java:29)
    There is a variable with a null value on line 29. Look at line 29 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 29 and print out the values of all the variables on that line.
    Ok thanks, will try that. If it doesnt work I will get back to you.

    -Luke

    --- Update ---

    I tried it, but I cant seem to find what is causing it. Could I send you source some how?

    -Luke

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    Super Moderator Norm's Avatar
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    Default Re: I have a NullPointerException error that I dont understand

    Post the code you added with the println() and the line with the error. Also post what the println() printed out.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: I have a NullPointerException error that I dont understand

    Quote Originally Posted by Norm View Post
    Post the code you added with the println() and the line with the error. Also post what the println() printed out.
    I cant, because it is a class that only runs methods, and the variables are type BufferedImage.

    (What I mean by that is that it is the type: int, boolean ect. IE:
    public static BufferedImage exampleVariable;

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    Super Moderator Norm's Avatar
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    Default Re: I have a NullPointerException error that I dont understand

    What do you expect anyone can do with that?
    What code is on line 29?
    What was printed out by the println you added?
    If you don't understand my answer, don't ignore it, ask a question.

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