Description
The following required classes are available for download via Canvas: MyDoublyLinkedList, MyList, MyAbstractList,
MyAbstractSequentialList, and TestMyDoublyLinkedList.
## Assignment Guidelines
The task for this assignment is to create a public, concrete class – “MyDoublyLinkedList“ – that extends
“MyAbstractSequentialList“ and implements “Cloneable“. The class must override “clone()“ and “equals()“ that
are inherited from “Object“ and all supported methods should work just like those in “java.util.LinkedList“. The
code should be tested with “TestMyDoublyLinkedList“, ensuring that tests 1 through 40 execute successfully.
This class must be implemented using a circular doubly-linked list with a dummy head node. Each node should have three
data fields: one for the element, one for the previous node, and one for the next node. Note that the first element of
a non-empty list is “head.next.element“ and the last element of a non-empty list is “head.prev.element“.
The methods “contains()“, “indexOf()“, and “lastIndexOf()“ should compare elements to “e“ by checking equality
with “equals()“. I may need to handle a null-value as a special case because the call “e.equals(…)“ will throw
a “NullPointerException“ if “e“ is null.
I will also need to write an inner class that implements the “ListIterator“ interface. Carefully read the Java
documentation on “ListIterator“ “add()“, “remove()“, and “set()“, and note that the latter two need to throw
an “IllegalStateException“ in certain circumstances.
### Tips
**Tip 1:** it is not necessary to override “equals()“ in “MyDoublyLinkedList“ in order to write “contains()“,
“indexOf()“, or “lastIndexOf()“. The “equals()“ method that will be called in these methods is the one provided
by the elements of the list, not the method provided by the list class.
**Tip 2:** it is necessary to understand how “ListIterator“ is expected to work for implementing
“MyAbstractSequentialList“. The following is a description of “ListIterator“ from Java documentation. Specifically,
it is important to understand how “remove()“ and “set()“ work.
– if you have invoked “next()“, then call “remove()“, it will delete the node that is previous of current
– if you have invoked “previous()“, then call “remove()“, it will delete the node that is current
– if you have invoked “next()“, then call “set()“, it will set the node that is previous of current
– if you have invoked “previous()“, then call “set()“, it will set the node that is current
– by default, you cannot call “remove()“ or “set()“ before invoking “next()“ or “previous()“
– after you have called “add()“ or “remove()“ once, you cannot call “remove()“ or “set()“ before invoking
“next()“ or “previous()“ again
**Tip 3:** in “remove()“ of the iterator, you will probably switch based on value of “iterState“, which indicates
if a node can be deleted, cannot be deleted, and if the previous node can be deleted or not.
– if the value of “iterState“ is “CAN_REMOVE_PREV“, consider whether you need to update “indexOfNext“; hint: the
index of the next element will be changed by the deletion
– if the value of “iterState“ is “CAN_REMOVE_CURRENT“, consider whether you need to update “current“; hint: you
do not want current to point to a node that is no longer in the list
## Submission
Submission of “MyDoublyLinkedList“ can be completed via Canvas.
