Question

Very simple error I’m sure, just having a mental block for some reason!

I have an object which contains an ArrayList of other objects. When I try to initialise the list in the constructor it does not seem to initialise and I get a nullpointer when I attempt to access the list within the code.

Order class variables:

private int covers;
    private int table;
    private ArrayList<MenuItem> items;

Here is the Order class:

public Order(int covers, int table) {
    super();
    this.covers = covers;
    this.table = table;
    this.items = new ArrayList<MenuItem>();
}

Here is the code within the MainActivity causing me problems:

order = new Order();
    order.setCovers(2);
    order.setTable(1);
    order.addToOrder(new MenuItem("Item 1", 12.99));
    Toast.makeText(getApplicationContext(), "order size: " + order.getItems().size(), Toast.LENGTH_SHORT).show();

I would expect the Toast to display “1”. However when I ran debugger I noticed the order object ArrayList attribute was equal to null.

Any idea why? Thanks in advance!

EDIT: addToOrder method:

public void addToOrder(MenuItem m){
    items.add(m);
}

Answer 1

You have failed to initialize items. Use

vorder = new Order(int1, int2);

instead of

vorder = new Order();

items is initialized inside

public Order(int covers, int table) {

}

not on the default constructor.