Java Warning using Vectors: unchecked call to add(E)
java, vector
Solution
The problem is that the code above is not using generics.
The following will work:
Vector<Integer> moves = new Vector<Integer>();
move.add(new Integer(x));
The type name inside the `<>` (in the case of `Vector`, the type parameter `E` for the element to hold) tells the compiler what type of object it should expect.
If one tries to add an object that is of the specified type, such as in this case, trying to add an `String` to and `Vector<Integer>`, an compile-time error will occur, indicating that a type of object that is not of the expected type is being added.
That said, one should try not to use the `Vector` class. For more purposes, a class implementing `List` such as `ArrayList` from the Java Collections Framework would be sufficient, and better performing.
Edit
Although not directly related to the question about generics, Adam Paynter brought up a good point in the comments about the use of auto-boxing.
Since Java 5, primitives and their wrapper classes, e.g. `int` and `Integer` will be automatically converted between each other as necessary.
Therefore, it is possible to add an value specified as an `int` or an `int` literal into a class expecting an `Integer`:
Vector<Integer> v = new Vector<Integer>();
v.add(5); // Not necessary to use an Integer value.
Problem
Offending bit of code ``` Vector moves = new Vector(); moves.add(new Integer(x)); ``` Error: ``` ConnectFour.java:82: warning: [unchecked] unchecked call to add(E) as a member of the raw type java.util.Vector moves.add(new Integer(x)); ``` Not really sure how much info is needed for an error like this....