Question

Here’s a constructor I have for Electronics that checks if the State input is valid.

public Electronics(String name, double price, int quantity, double weight, boolean frag, String s)
    {
        super("Electronics",name,price,quantity,weight);
        fragile=frag;
        s=s.toUpperCase();
        if(checkState(s)==true)
        {
            state=s;
        }
        else
        {
            out.println("ERROR - not a valid state abbreviation");
        }
    }

However in my main(), I have something like this:

public List<Item> shoppingCart = new ArrayList<Item>();
temp= new Electronics(name,price,quantity,weight, fragile, state);
...
shoppingCart.add(temp);

So even if the state abbreviation is not valid, (it just prints out that state is not valid) but the object is still added to the ArrayList. What can I do to stop the add if the state abbreviation is not correct?

Answer 1

You should throw an Exception and handle it in your main(), IllegakArgumentException is probably the best fit here.

Something like:

    ...
    else
    {
        throw new IllegalArgumentException("...");
    }
    ...

in main:

public List<Item> shoppingCart = new ArrayList<Item>();
try { 
   temp= new Electronics(name,price,quantity,weight, fragile, state);
   ...
   shoppingCart.add(temp);
} catch (IllegalArgumentException e) { 
  //handle exception
}

Note that if the exception will be thrown by the constructor, the program will not reach the insertion of the element to the list.