您如何在Java中使用泛型来进行对象的等效转换？

Question

I'm creating an object stack which uses a doubly linked list in order to reference the bottom objects as they are popped off the stack. My dilemma is that I have multiple classes which take in objects as parameters. The objects represent instances of the other classes so they are not accepted as parameters into a different class unless the methods and fields of that receiving class are declared with the name of the sending class. I don't want the classes to be dependent off of each other since I want to use the doubly linked list later on in other programs. So I am contemplating writing generics into my program or casting the objects. Which do you think is the better choice and why? Also how would the approach be implemented?

Answer 1

I think you should use generics. They are a new feature added to Java 5 for type safety and to prevent inadvertent ClassCastException s. Here is a basic prototype of a stack implemented using generics:

public class GenericStack<E> {   //'E' is your type parameter, which can be any legal
                                    //identifier, but a capital letter is suggested
    public void push(E obj) {    //use your type parameter name as though it is
                                     //an actual type
        //implementation here
    }

    public E pop() {
        //implementation here
    }
}

Answer 2

If you are going to want to use your stack with many different object types, then generics are very helpful. This would be especially helpful since you say that you will want to use your stack later in other projects, but don't know yet which objects you will want to build the stack with.

You can find out more about generics here , but the basic syntax to create such a class would be like this:

 public class Stack <T>

Where T stands for type.

When you create an object of this class, you will do so like this:

 Stack <Integer> stack1 = new Stack <Integer>();

In place of "Integer", you would put the object type that you will be storing in the class.