How can I increment a variable on button click?

Question

I'm trying to make a small game like thing for school. It's designed to help you learn your times tables. What I want is for the multiplier of the table to be random each time (5x8 then 5x3 then 5x9 etc).

I've got the generating of the numbers in control with an array as can be seen below

public static Integer[] generateNumbers()
{
    Integer[] arr = new Integer[12];

    for(int j = 0; j < arr.length; j++)
    {
        arr[j] = j+1;
    }
    Collections.shuffle(Arrays.asList(arr));
    System.out.println(Arrays.asList(arr));
    return arr;
}

How can I make it so that every time the user clicks a button, the next number in the array is selected, baring in mind that the button is declared in another class, and the ActionListener is also declared elsewhere?

Oh and the array is available class-wide as the function is declared like this:

public static Integer[] arr = generateNumbers();

@feuerball I didn't put the button declaration in the post. I can if you want.. — Jake Stanger
– Jake Stanger, Commented Apr 1, 2014 at 12:03
You don't need to see it, the action listener will be called when the button is clicked. — MrHaze
– MrHaze, Commented Apr 1, 2014 at 12:04
@feuerball the actionlistener is in another class. The button responds. That's not my problem... — Jake Stanger
– Jake Stanger, Commented Apr 1, 2014 at 12:10

Anthony Accioly · Accepted Answer · 2014-04-01 12:29:17Z

1

Thematic answer

public class UnicornFrame extends JFrame {

     private Integer[] poneyArr = MyClassThatGeneratesNumbers.generateNumbers();
     private int poneyCounter = 0;
     private JButton poneyButton;

     public void poneyInit() {
         System.out.println("Unicorns are poney magical friends!");
         poneyButton = new JButton("OMG! Ponies!");
         // Java 8 Lambdas! Yey!
         poneyButton.addActionListener(e -> { 
             if (poneyCounter >= poneyArr.length) {
                  poneyArray = MyClassThatGeneratesNumbers.generateNumbers();
                  poneyCounter = 0;      
             }         
             Integer selected = poneyArr[poneyCounter++];   
             System.out.println("OMG! I have selected " + selected);
         });

         // other stuff

         add(poneyButton, BorderLayout.CENTER);
     }
}

edited Apr 1, 2014 at 12:29

answered Apr 1, 2014 at 12:13

Anthony Accioly

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Comments

MrHaze · Accepted Answer · 2014-04-01 12:03:12Z

0

The button int he separate class is not needed, the action listener will communicate with your array whenever its clicked, the easiest way I see is to put a public method int the array's class, that takes an index, which then increments the index, and returns the element stored at it.

Have fun coding, but these assignments are meant for you to scratch your head, try writing some code, and let us know if it breaks, rather than asking for general answers.

answered Apr 1, 2014 at 12:03

MrHaze

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5 Comments

Jake Stanger Over a year ago

I'm being stupid here - what do you mean by an index?

MrHaze Over a year ago

No problem, nothing wrong with asking :) index is how you access an element in an array so this 'array[3]' here 3 is the index, and that would return the 4th element in the array because arrays start at index 0.

Jake Stanger Over a year ago

I thought that may have been the case. Thanks.

Jake Stanger Over a year ago

Ok I've been pondering over this for a while now. How do I take the index in the first place?

MrHaze Over a year ago

That depends on how you are implementing things, and when you find out, pass it as a parameter.. or which ever suits best for how you did things.

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