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Thread: int cannot be dereferenced

  1. #1
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    Default int cannot be dereferenced

    hello,

    why do i get the error/message "int cannot be dereferenced" in bluej?

    import java.util.Random;
     
    public class KassaSimulator
    {
            private int nKlanten,  vKlanten,  tSteps,  klantnummer;
            private Queue[] kassas;
            private Random rng;
     
            public KassaSimulator(int kassas, int aantalKlanten, int verwerkKlanten, int tijdstappen)
            {
                this.kassas = new Queue[kassas];
     
     
     
                for (int i = 0; i < kassas.length; i++)
                {
                    kassas[i] = new Queue(aantalKlanten * 2); 
                }

    i get the error within the first for loop

    for (int i = 0; i < kassas.length; i++)
                {
                    kassas[i] = new Queue(aantalKlanten * 2); 
                }
    it is highlighting the kassas.length
    System.out.println(" dream in code ");


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    Default Re: int cannot be dereferenced

    it is referring to the integer being passed into the method, If you want to refer to the queue then you need to add the keyword "this"

    for (int i = 0; i < this.kassas.length; i++)
                {
                    kassas[i] = new Queue(aantalKlanten * 2); 
                }

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    Default Re: int cannot be dereferenced

    The int variable kassas is a parameter of the method KassaSimulator() here:
    public KassaSimulator(int kassas, int aantalKlanten, int verwerkKlanten, int tijdstappen)
    //                               ^
    //                                | here kassas is a local int variable to the method
    and then kassas is used as an array of (? what) in the for loop:
    for (int i = 0; i < kassas.length; i++)
    //                               ^
    //                                | here kassas is being treated as an array with attribute 'length'
                {
                    kassas[i] = new Queue(aantalKlanten * 2); 
                }
    Since ints have no attributes and cannot have methods called on them like objects, then you're getting the error.

    Bottom line is, you can't do that with an 'int', and you shouldn't be trying to.

    Edit: Another good example of why keeping variable/method names meaningful and unique reduces confusion and errors.

  4. #4
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    Default Re: int cannot be dereferenced

    This is a scope issue. You have your queue named: "kassas", but you also have a variable in the parameters of your constructor named: "kassas", which is an int. When you don't use a qualifying keyword (such as this.), java will look for the variable with the closes scope. In this case, it is attempting to call the .length method on your kassas int parameter, not your kassas queue.
    One solution is to use this.kassas.length (like you do when you construct the queue a few lines before), but a potentially "better" solution would be to rename the int kassas parameter to something which makes more sense (perhaps kassasLength).
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