CODEWITHSUNDEEP
javagenerics
achAmháin
achAmháin

Reputation: 4266

Parameterizing a raw type

I have a Vector like so:

Vector myVector = new Vector();

And an ArrayList of a custom class which contains n amount of Strings.

Basically, I add an empty item into the first position in the Vector (myVector.insertElementAt("", 0);), and then add (usually) the rest of the items from the ArrayList (depending on the needs). This Vector then is used as the the DefaultComboBoxModel for a JComboBox.

Now, I get the usual warning References to the generic type Vector should be parameterized.

The items are of type String, but I can't use Vector<String> because adding the items from the ArrayList (using .add()) won't work as:

The method add(String) in the type Vector(String) is not applicable for the arguments (CustomClass).

I can't use Vector(CustomClass) because then insertElementAt throws a wobbler.

So my question is: Is it safe to just use Vector(Object) or not parameterize the type at all?

I could use T and cast everything but would get a type safety error.

Upvotes: 0

Views: 65

Answers (1)

Andy Turner
Andy Turner

Reputation: 140319

I can't use Vector because adding the items from the ArrayList (using .add()) won't work as:

The method add(String) in the type Vector(String) is not applicable for the arguments (CustomClass).

So, you are trying to add things from an ArrayList<CustomClass> to a Vector that you expect only to contain String elements.

If you are using a raw-typed Vector, you can do this, but it will fail down the line if you try to do anything with an element from that Vector that you treat as a String, because it's not.

If you want the Vector to contain Strings, add a String:

myVector.add(thingFromArrayList.toString());

(or some other means of converting thingFromArrayList to a String)

and then you can add the <String> to myVector's type.

Upvotes: 1

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