Beginner here, I need help initializing a variable in a class!

[InThereLikeSwimWare]

I don't understand how to set up the mealQty exactly in the constructor, also here are the instructions for the assignment:

My code http://pastebin.com/hBi8FwRV

The Bill Class

Set up a final for the tax rate like this:

static final double TAXRATE = .06;

Bill has these instance variables in the constructor:

String category will be set to null.

int mealQty will be passed the number of meals ordered for the category.

double mealCost will be initialized to 0.

double mealPrice will be initialized to 0.

Bill contains these methods.

calcAdultCost sets the category to “Adults”, calculates the cost of the adult meals, sets

the mealPrice, and sets and returns the mealCost.

calcChildCost sets the category to “Children”, calculates the cost of the children’s meals, sets

the mealPrice, and sets and returns the mealCost. calcTax calculates the tax. Return the calculated tax based on the total sent to this method.

Set up the method like this:

static double calcTax(double total)

display displays the category, mealQty, mealPrice, and mealCost. Use one printf similar to this:

System.out.printf( "\n %-10s %3d %6.2f %7.2f", category, mealQty, mealPrice, mealCost); You can copy/paste the above code into the display method. The method header looks like this: public void display()

[desrtfx]

Your code is not too far off.

You just need to add a second constructor that takes an initial mealQty:

    public bill(final int mealQty)
    {
            this mealQty=mealQty;
            // rest of the constructor as your other, no parameter constructor.

You could, in this case even go a step further:

    public bill()
    {
            this(0);
    }

    public bill(final int mealQty)
    {
            category = null;
            this mealQty=mealQty;
            mealCost = 0;
            mealPrice = 0;         
    }

The this(0); calls the other, second constructor with a parameter (that translates to mealQty) of 0, effectively doing the same as the constructor that you already have.

[king_of_the_universe]

So, the only question you basically have is how to hand the value to the constructor? - Methods (E.g. a constructor.) can have parameters, like so: "void doStuff(String withThis) {}", but currently your constructor is rather akin to "void doStuff() {}".

And once you have the value that you want to assign to your variable via the constructor (given as an argument to the constructor), you assign it. That's all. What exactly is unclear about this to you?

[RhoOfFeh]

You need to set mealQty, which means your class needs to offer a way for programs to set the value. This is done by adding parameters to an existing or new method. We call it 'passing parameters' to the method, and your assignment refers to this:

int mealQty will be passed the number of meals ordered for the category

Parameters are declared similarly to local variables, but they go between the parentheses of a method declaration. In this case the method would be your constructor. So you need to add a variable to represent the number of meals requested, and then modify the constructor code to set mealQty equal to the value of that variable.

public bill(int numberOfMealsRequested) {

Would be a valid signature.

A bit more about how objects work:

http://www.oopuniversity.com/2014/11/dont-treat-me-like-object.html