Homework # 8 Generics and Collections in Java Solution

As we discussed in the lectures, Java has a very structured Collections library. We can develop a similar simplified library for Java that uses arrays underneath. We will implement some the interfaces some abstract class, some concrete classes, and some of the helper classes such as iterators.










The above figure shows a simplified version of the Collections. We will write corresponding generic classes for Collection, Set, List, Queue, which are all interfaces. HashSet, ArrayList, and LinkedList are concrete classes. Note that LinkedList uses multiple inheritance. Following table defines the functions for each class




Class Name
Public Method Name
Definition
Collection
This is a generic class with one generic parameters which is the generic type E.


iterator()
Returns an iterator over the collection












add(E e)
Ensures that this collection contains the specified element












addAll(Collection c)
Adds all of the elements in the specified collection to this








collection


clear()
Removes all of the elements from this collection












contains(E e)
Returns true if this collection contains the specified element.












containsAll(Collection c)
Returns true if this collection contains all of the elements in the








specified collection.


isEmpty()
Returns true if this collection contains no elements.












remove(E e)
Removes a single instance of the specified element from this








collection, if it is present


removeAll(Collection c)
Removes all of this collection's elements that are also contained








in the specified collection





retainAll(Collection c)
Retains only the elements in this collection that are contained in








the specified collection


size()
Returns the number of elements in this collection.




Set
A collection that contains no duplicate elements. There is no order for this collection. In other


words, you don’t have to keep the insertion order of the elements.
List
An ordered collection (also known as a sequence). The user of this interface has precise


control over where in the list each element is inserted.
Queue
Queues order elements in a FIFO (first-in-first-out) manner. There is no random access with


this Collection. Some functions throw exceptions.


add(E e)
Inserts the specified element into this queue


element()
Retrieves, but does not remove, the head of this queue.


offer(E e)
Inserts the specified element into this queue


poll()
Retrieves and removes the head of this queue, or throws if this




queue is empty.
HashSet
Implements Set functions


ArrayList
Implements List functions


LinkedList
Implements both List and Queue functions. Your class does not have to have a linked list to


implement these.


Iterator
hasNext()
Returns true if the iteration has more elements.


next()
Returns the next element in the iteration and advances the




iterator.


remove()
Removes from the underlying collection the last element returned




by this iterator



Your Java Collections hierarchy should use only Java arrays in the concrete classes to implement all the methods.




You will test each method of each concrete class with generic parameters of int and string.




Notes:




Do error and range checking for any parameters. Throw exceptions and test them in your client code. Do not forget to define the throw lists for your functions.



For each class you will write appropriate class documentation for Javadoc. You will also submit the Javadoc files.



As expected, you should follow all object-oriented programming principles.



You should submit your work to the moodle page.



You should submit the images of drawn shapes.