lost values

[emosms]

Hi,
I am trying to resize an aray having the following method:

    private void resize(int size) { // resizing the array
        Item[] temp = (Item[]) new Object[size];
        for (int i = 0; i < N; i++) {
            temp[i] = a[i]; // move the content to the new array
            System.out.println("1. Old array value: " + a[i] + "; @ index: " + i);
            System.out.println("2. Temp array value: " + temp[i] + "; @ index: " + i);
            a = temp;
        }
    }

But it seems that values ar lost when copying, I have the following output:

Enqueued Item: 2; @ array index: 1; Array length: 2
1. Old array value: 1; @ index: 0
2. Temp array value: 1; @ index: 0
1. Old array value: null; @ index: 1
2. Temp array value: null; @ index: 1

a is a generic array declared as:

public Item[] a; // queue items

and initiated in the constructor:

a = (Item[]) new Object[1];

The client populates the array, but each time it goes to resizing (enlarging) the old values are just NULL.

Here is the method that adds items (called enqueue, but in fact is just pushing ellements into the array for now):

    public void enqueue(Item item) { // add an item
        if (N == a.length) {
            resize(2 * a.length); // double the array
            a[N] = item;
     }
     a[N++= item;
}

Dont know why when I call the class variable a[] to copy it, it has NULL values except at index [0]

Best Regards

[Fubarable]

What does this do inside the for loop?

a = temp;

Also, have you looked at System.arraycopy?

[emosms]

what is system arraycopy?
It is schools assignment, we are to implement the resize() method ourselves.

a = temp; - supposed to assign back the whole new array object to the variable a
BTW, the resize() method is as is from our notebook

[Fubarable]

what is system arraycopy?
It is schools assignment, we are to implement the resize() method ourselves.

fair enough.

a = temp; - supposed to assign back the whole new array object to the variable a
BTW, the resize() method is as is from our notebook

But as I mentioned before, look at where you're doing this -- inside the for loop. You need to think logically what this will do to the array that you're trying to convert.

[emosms]

god, i've spent the whole afternoon not seeing it. this is insane.
thx!

[Fubarable]

You're welcome!