Question

public void printList( ){
    Node<E> p ;
    System.out.printf( ” [ ” ) ;
    for ( p=head.next ; p != null ; p=p.next )
        System.out.print( p.element ) ;
    System.out.printf( ” ] ” ) ;
}

public void addLast (E e){
    Node<E> p = head;   // <--- data type Node<E>, var name = p, but what is head type?
    while ( p.next != null )
        p = p.next ;
    p.next = new Node<E>(e , null ) ;
}

Generics Example:

public class Box {
private Object object;

public void set(Object object) { this.object = object; }
public Object get() { return object; }

}

Using Generics:

// T stands for "Type"
public class Box<T> {
    private T t; 

    public void set(T t) { 
        this.t = t;
    }
    public T get() { 
        return t;
    }
}

I have a general idea of how linked list work intuitively however I can’t see it in code.

I know you have the element and a reference to the next node. In the code above, how does the “.” operator work as it traverses through the list until null is reached?

I believe ‘next’ is a reference variable. when it does p=p.next, how does it work in code/computer?

On a unrelated note, node ? instead of node(E)? difference? In the example above, it seems ‘object’ was replaced by ‘t’, i can’t see the advantage. ;S

Any help is really appreciated, thanks in advance!

Answer 1

It might help to think of a LinkedList as a List of linked Nodes. Where each Node will hold a reference to the next Node (if one exists). I’m not sure if it will help, but when I had to do this assignment in School I found that looking through the API and trying to use it very helpful.

With Generics Node will be a Node of type Object Where Node will be a Node of a specific type. For example, LinkedList will hold Strings. This, might help to get a better understanding of how generics work.

Here is a simple example of using generics:

Class Box<E>{
    private E variable;

    public E get(){
        return variable;
    }

    public void set(E variable){
        this.variable=variable;
    }

    public static void main(String[] args){
        Box<String> example=new Box<String>();
        example.set("test");
        System.out.println(example.get());

        Box<Integer> example2=new Box<Integer>();
        example2.set(1);
        //example2.set("test");will not work because it is types as an Integer
        System.out.println(example2.get()+1);
    }
}