array in GUI

I need to array each drink, so that when value is input, the supply decreases by 1, and it displays back to the supply JTField. Here's my coding but it returns null value instead.

Quote:

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code:
public void actionPerformed(ActionEvent e)
{
double num1 = Double.parseDouble(jtf2.getText().trim());
double result = 0.0;
double change = 0.0;
VendMach v[] = new VendMach[0];
VendMach v1[] = new VendMach[0];

count--;
for(int i = 10; i >= v.length; i--){
if(e.getSource() == jbt1)
{
result = 1.20;
change = num1 - result;
coffee.setDrink("latte");
coffee.setResult(result);
coffee.setAmount(num1);
coffee.setChange(change);
coffee.setSupply(i--);
}
}

count--;
for(int i = 10; i >= v1.length; i--){
if(e.getSource() == jbt2)
{
result = 1.30;
change = num1 - result;
coffee.setDrink("White Coffee");
coffee.setResult(result);
coffee.setAmount(num1);
coffee.setChange(change);
coffee.setSupply(i--);
}
}

jtf1.setText(String.valueOf(result));
jtf3.setText(String.valueOf(change));
jtf4.setText(String.valueOf(supply));

showMessageDialog(null, coffee.toString());

}

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What returns a null value?
Also does it give you any exceptions? If so post the whole stacktrace

i'm trying to decipher your code here:

the i is from the for loop. and you are already decrementing it to begin with. Is that how you intend it?

I'll try to be helpful but i need clarification on what the code itself is doing, thanks.

setText(String s); is a void method, it's not supposed to return anything.
Btw try doing something like jtf4.setText(coffee.getSupply());

Quote:

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Originally Posted by creedkorn

http://s1098.photobucket.com/albums/...t=Untitled.png
Untitled.png picture by creedkorn1 - Photobucket

Here's the program, and the supply shows null value. "i" is supposed to be a variable for 'supply' and, for example, if the latte button is pressed, 'i' decrements, and show's the after result.

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You decrement "i" but I can't see you decrementing the "supply" field

well the value of i is returned to the supply field, i.e 'i' value is supply value. is it possible ?

Quote:

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Originally Posted by creedkorn

well the value of i is returned to the supply field, i.e 'i' value is supply value. is it possible ?

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i is not the supply value, i is i and supply is supply.

What happened when you tried coffee.getSupply()?

Please post the whole class where you put that "actionPerformed()" method, I'm still trying to understand what you are trying to do. (in code tags and not quote tags :p)

Code:

---

VendMach v[] = new VendMach[0];
VendMach v1[] = new VendMach[0];

---

Why are you creating two new arrays with zero size each time that method is run? As far as I can see, all you are using them for is the for-loops (which I have no idea why you are using either).

Quote:

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The coffee.setSupply(i--) sends the decremented i value to the supply text field

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No, that sends the value of i to the coffee object.

I need to for loop each object(i.e latte, white coffe, etc) into an array of size 10. Simply put, there is 10 of each drink in stock. Now, when the user chooses a drink, stock for drink decreases......so i was doing for loops for each objects for.

What's the coding error with passing i value to supply text field ?

I have edited your post #14 above and have changed your [quote] [/quote] tags to [code] [/code] tags so that the code formatting won't be lost.

Thanks, so any idea what the error is in the GUI class, because the output seems to be different from the coding ?