Question

I want to write a function which would return me a Vector of the specified type which I pass to it. For example:

// Here getNewVector(<ClassType>) should return me an integer Vector.
Vector<Integer> myIntVector = getNewVector(Integer.class);
//should get a String vector in this case and so on.
Vector<String> myStringVector = getNewVector(String.class) ; 

I want to implement getVector(Class classType) in such a way so as to return a new vector of that particular class type. How can we achieve it without using reflections and by not passing the class name as a String(I would like to pass the class type only as I had mentioned in the example above.)

Actually, I want a function getVector() somewhat like this..

Vector<T> getVector(T t) {
    return new Vector<t>();
}

Answer 1

Take a look at the Java Tutorial for Generic Methods. Here’s one way to do what you want:

public static <T> Vector<T> getVector(Class<T> clazz) {
  return new Vector<T>()
}

public static <T> Vector<T> getVector(T t) {
  Vector<T> vector = new Vector<T>();
  vector.add(t);
  return vector;
}

I’m assuming that you’re not going to just want to throw away the t you pass into getVector(T t), so I stuck it in the Vector.

Theoretically, you don’t need to pass anything into the method if all you want is the typing mechanism:

public static <T> Vector<T> getVector() {
  return new Vector<T>();
}

//Usage
Vector<Integer> vector = getVector();

Java can figure out that you want it typed as a Vector<Integer> from the generic typing on the declaration.