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Thread: method not working outside of class

  1. #1
    Member Scotty's Avatar
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    Default method not working outside of class

    I have a 2D-array in a class, and methods that affect the array.

    From another class I can call a method to add to the array which works fine.

    My method to get a value from an array is:

     
    public int getValue(int col, int row){
     
    		return myArray[col][row];
    	}

    I can call it in that class and it works fine (returns correct int), but from another class I always get a null pointer exception. All other methods work from another class (ie to set a value in the array). Why cant I return the value?

    int Number = class.getValue(); -- null pointer.


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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: method not working outside of class

    Sounds like your reference to "class" is null. Are you sure you're initializing it?

    That's just a guess though. If you want more help, you'll have to provide an SSCCE that demonstrates the problem. That doesn't mean you should post your whole program- just the bare essentials.
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  3. #3
    Member Scotty's Avatar
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    Default Re: method not working outside of class

    I can use other methods, for example

    state.setArray(2);

    Which puts a value in row 2 and then prints the array. These work fine.
    It is definitely initialised. I cannot post code.

    I have tried

    public int getValue(int col, int row) {
    int Number = myArray[col][row];
    return Number;
    }
    state state;
    state.getValue(1,2);
     
    also
     
    state teststate = new state();
    teststate.getvaule(1,2);
     
    for a copy of state

    But I get the same error. I dont see why that would work if the other one didnt.
    Last edited by Scotty; April 22nd, 2011 at 02:57 PM.

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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: method not working outside of class

    If you can't post an SSCCE, then we can't really help you. Are you sure the array is initialized?
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