9. Iterators

Feel free to use your laptop
You are strongly encourage to work with others
- When you get stuck, ask those sitting around you for help
- Get used to working together in the labs
- Peer teaching and peer learning has been empirically shown to be very effective

9.1. Playing with Iterators

The goal is to redefine stacks and queues such that the collections are iterable based on the details discussed in the Iterators Topic.

9.1.1. Create an Array Iterator

Create an ArrayIterator class that implements the Iterator interface

Note

Obviously one can simply download the ArrayIterator code, but this defeats the purpose of the lab. Instead, slowly and deliberately implement each method and take the time to understand the details.

9.1.2. Create an Iterable Stack

Download the Stack interface and add it to the project
Modify the interface such that Stack extends Iterable
Add the required iterator method to the interface
Download the ArrayStack class and add it to the project
Modify the ArrayStack such that it implements the iterator method
- Simply have it return the ArrayIterator
Modify the existing toString method such that it uses an iterator
- Refer to the toString from the ArraySortedBag for help

Note

What order are the elements returned by the iterator for the ArrayStack? Should it start at index 0 or at the top?

9.1.3. Create an Iterable Queue

Download the Queue interface and add it to the project
Modify the interface such that Queue extends Iterable
Add the required iterator method to the interface
Download the ArrayQueue class and add it to the project
Modify the ArrayQueue such that it implements the iterator method
Modify the existing toString method such that it uses an iterator

9.1.4. Make the Linked Stack and Queue Iterable

Repeat the same ideas for the LinkedStack and LinkedQueue.

9.1.5. Improve `equals`

The current implementations of the Stack and Queue objects are only able to be equal to instances of the exact same type. For example, it is currently only possible to have an ArrayStack be equal to another ArrayStack. However, this is less than ideal as it should be possible to check equality between Stack objects, regardless of their specific implementation. In other words, it should be possible for an ArrayStack to be equal to a LinkedStack.

Modify the existing equals methods within the various stack and queue implementations such that it is possible for Stack and Queue instances to be equal, regardless of their specific implementation.