Increment an integer variable?

Question

I am having a problem incrementing my integer variable after a certain condition is met in Android Programming. Why is it not incrementing?

The code below are implemented on an ImageButton which lies a class (Activity) called Product.

int count = 1;

List<Item> prod = ShoppingCart.getInstance().getProducts();

// if arraylist is null --> add a product
if(prod != null && prod.isEmpty()){
    ShoppingCart.getInstance().addItem(new Item(
            namePureString,
            manufacturePureString,
            pricePureString,
            "",
            count
    ));
    Toast.makeText(getApplicationContext(), namePureString + " Added To Cart", Toast.LENGTH_SHORT).show();

}else {

    for (Item products : ShoppingCart.getInstance().myProducts) {

        // here i am checking if the product exists, if it does --> count has to increment
        if (products.getManufacture().equals(manufacturePureString)) {

            count += count;
            Toast.makeText(getApplicationContext(), "You Added This Product\nQuantity Will Increase",
                    Toast.LENGTH_SHORT).show();

            ShoppingCart.getInstance().setItemExists(new Item(
                    namePureString,
                    manufacturePureString,
                    pricePureString,
                    "",
                    count
            ));

            } else {
            ShoppingCart.getInstance().addItem(new Item(
                    namePureString,
                    manufacturePureString,
                    pricePureString,
                    "",
                    count
            ));
        }
}

This is my Singleton class, in which I call its methods:

public class ShoppingCart {

    private static final String TAG = "Products: ";
    private static ShoppingCart ourInstance = null;

    public ArrayList<Item> myProducts = new ArrayList<>();

    private ShoppingCart() {
    }

    public static ShoppingCart getInstance() {
        // if object instance does not exist create a new one and use that one only
        if ( ourInstance == null){
            ourInstance = new ShoppingCart();
        }
        return ourInstance;
    }

    public void addItem(Item item){
            ourInstance.myProducts.add(item);
    }

    public void setItemExists(Item item) {
        int itemIndex = ourInstance.myProducts.indexOf(item);
        if (itemIndex != -1) {
            ourInstance.myProducts.set(itemIndex, item);
        }
    }

    public List<Item> getProducts(){
        return this.myProducts;
    }
}

Answer 1

count++ is the same as count = count + 1 and not count += count in your Code. Count += count adds the amount of count on top of the value of count.

So to increment add this:

count = count + 1; //or count++;