Another cannot find symbol variable thread

[filipek]

Good afternoon,
My assignment is due tonight, and Im running into some problems with the Java compiler. This is my code:

public class DoublyLinkedList<T> implements SimpleList<T> {

protected Node dummy;
protected int n;
public DoublyLinkedList() {

dummy = new Node();
dummy.next = dummy;
dummy.pre = dummy;
n = 0;
throw new NotYetImplementedException();
}

public void addFirst(T o) { throw new NotYetImplementedException(); }

public void addLast(T o) { throw new NotYetImplementedException(); }

public void add(int index, T element){ throw new NotYetImplementedException(); }

public T getFirst() { throw new NotYetImplementedException(); }

public T getLast() { throw new NotYetImplementedException(); }

public T get(int index) { throw new NotYetImplementedException(); }

public void clear() { throw new NotYetImplementedException(); }

public T remove(int index){ throw new NotYetImplementedException(); }

public boolean remove(Object o){ throw new NotYetImplementedException(); }

public T removeFirst() { throw new NotYetImplementedException(); }

public T removeLast() { throw new NotYetImplementedException(); }

public T set(int index, T element){ throw new NotYetImplementedException(); }

public int size() { throw new NotYetImplementedException(); }

public boolean contains(Object o){ throw new NotYetImplementedException(); }

public int indexOf(Object o){ throw new NotYetImplementedException(); }

}

public class Node<T> {

public Node() {
Node pre;
Node next;
T data;
}


}

I want to use a dummy node in my implementation of the Doubly Linked List, so it will be easier to code all the methods I need to write.
I keep on getting a problem with line 14 and 15:
dummy.next = dummy;
dummy.pre = dummy;
// cannot find symbol variable next (compiler error)
// cannot find symbol variable pre

I haven't programmed for a while, I know I made some newbie mistake. Thanks in advance,
Mark.

[wsaryada]

You've declared the next and pre as local variable in the Node class constructor. So it won't available / accessible from outside the constructor.

[filipek]

I've changed the code of the Node class:

public class Node<T> {

public Node() {
Node pre;
Node next;
T data;
}


}


to

public class Node<T> {

Node pre;
Node next;
T data;



}


and it compiles now. I think that was the solution. Thanks for quick reply

[filipek]

I have another little problem now:

public T getFirst() {

return dummy.next.data; //error on this line
}

returns an error like this: 'incompatible types'

This is the code for a Node:

public class Node<T> {


Node pre;
Node next;
T data;



}

Thanks in advance. Mark

[DarrylBurke]

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