Generics related warning in Vector add method

[Leena Diwan]

Hi

I am creating a Vector instance.
And adding elements like vectorInstance.add("myData");

To the add method I am getting warning in my IDE (Eclipse) as following-
Type safety: The method add(Object) belongs to the raw type Vector. References to generic type Vector<E> should be parameterized

I am using jdk1.6. All I know is this is generics related warning.
What would be a good programming practice in this case?

Can you give me example? And where to check in case I get such warnings for any other classes in java?

Thank you!

Regards,
Leena

[Rob Spoor]

Lesson: Generics

In your case, declare and initialize your vector as this:

Vector<String> vectorInstance;
...
vectorInstance = new Vector<String>();

As a side note, don't declare vectorInstance as a Vector, but as a List:

List<String> listInstance;
...
listInstance = new Vector<String>();
// or:
listInstance = new ArrayList<String>();

This is called programming against interfaces; do a search around this forum to find out why this is better (the question has been asked many, many times).

[Jesper de Jong]

Another point: Is there a specific reason that you are using class Vector instead of class ArrayList?

Class Vector is one of the old legacy collection classes from Java 1.0 / 1.1. In Java 1.2 (long ago...) a new collections framework was introduced, including ArrayList to replace Vector (there are small differences, but those are not relevant for most situations). Prefer the newer classes such as ArrayList above the old ones such as Vector.

Also see the Collections trail in Sun's Java Tutorials.