Java: getting the current value of a static variable

Question

I'm trying to create a bunch of objects with unique IDs. My first idea for implementing this was to have a static variable that counted the amount of objects. Each time an object is created, the static variable is increased by one and written down as the ID of the object.

Gleefully, I implemented the code thusly:

    public class Order {
        static int totalOrdersPlaced;
        public int orderID;

        public void Order() {
            totalOrdersPlaced++;
            orderID = totalOrdersPlaced;
        }
    }

...which throws a "cannot make a static reference to the non-static field" error for reasons I roughly understand. But I can't quite figure out how to implement what I want.

tl;dr: How to I make the program get the current value of a static variable and store it?

Matt Ball · Accepted Answer · 2013-02-28 01:36:26Z

3

The code in your question compiles. Does your real code have public static void Order() instead?

Either way, I'm guessing you meant to do this in a constructor, so remove the void:

public class Order {
    private static int totalOrdersPlaced;
    public final int orderID;

    public Order() {
        totalOrdersPlaced++;
        orderID = totalOrdersPlaced;
    }
}

answered Feb 28, 2013 at 1:36

Matt Ball

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1 Comment

Klaabu Over a year ago

Oh. Oh dear. Yes, that was... The void was not supposed to be... I feel a bit dumb now. Thanks for the help. (and no, my real code did not have public static void Order())

Aniket Inge · Accepted Answer · 2013-02-28 01:40:40Z

1

 public class Order {
    static int totalOrdersPlaced;
    public int orderID;

    public void Order() {
        totalOrdersPlaced++;
        orderID = totalOrdersPlaced;
    }
}

will work if you convert Order() method to a constructor.(Remove the void).

Here is a test code:

 public class Order {
    static int totalOrdersPlaced;
    public int orderID;

    public Order() {
        totalOrdersPlaced++;
        orderID = totalOrdersPlaced;
    }
    public static void main(String[] args) {
    Order order = new Order();
    System.out.println(order.totalOrdersPlaced);
    Order order2 = new Order();
    System.out.println(order2.totalOrdersPlaced);
}
}

Proof: http://ideone.com/n06npg

answered Feb 28, 2013 at 1:40

Aniket Inge

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Comments

Pragnani Kinnera · Accepted Answer · 2013-02-28 01:41:43Z

1

Remove void in the

 public void Order() {
            totalOrdersPlaced++;
            orderID = totalOrdersPlaced;
        }

Constructor should not have return type

.. originally identified by MattBall

Generate getters and setters for the required variable and get the value by using getter method.

edited Feb 28, 2013 at 1:41

answered Feb 28, 2013 at 1:35

Pragnani Kinnera

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