Iterator pattern in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Iterator pattern?

The Iterator pattern is a design pattern that provides a way to access elements of a collection one by one without exposing its underlying structure.

beginner

Name the two main roles in the Iterator pattern.

The two main roles are: 1) Iterator - defines methods to traverse elements, and 2) Aggregate (or Collection) - provides a method to create an iterator.

intermediate

Why use the Iterator pattern instead of directly accessing a collection?

It hides the internal structure of the collection and allows different ways to traverse it without changing the collection's code.

intermediate

What methods are typically defined in an Iterator interface?

Common methods include: 1) hasNext() - checks if more elements exist, 2) next() - returns the next element, and sometimes 3) remove() - removes the current element.

beginner

Give a real-life example that explains the Iterator pattern.

Think of a TV remote to change channels. You don’t need to know how the TV stores channels; you just press next or previous to move through them one by one.

What does the Iterator pattern help to achieve?

A Traverse elements without exposing collection structure

B Store elements in a collection

C Sort elements in a collection

D Create new collections

The Iterator pattern allows traversal of elements without exposing the underlying collection structure.

Which method is NOT typically part of an Iterator interface?

A hasNext()

B next()

C add()

D remove()

add() is not usually part of the Iterator interface; it is a collection operation.

In the Iterator pattern, who creates the iterator?

A Aggregate or collection

B Iterator itself

C Client code

D External factory

The aggregate or collection provides a method to create an iterator.

Which of these is a benefit of using the Iterator pattern?

A Automatic data backup

B Direct access to collection internals

C Faster sorting

D Multiple traversal methods without changing collection

Iterator pattern allows different ways to traverse without changing the collection.

What is the main purpose of the hasNext() method?

A Return the current element

B Check if more elements exist

C Remove the current element

D Add a new element

hasNext() checks if there are more elements to iterate over.

Explain the Iterator pattern and its main components in your own words.

Think about how you would explain browsing a list without seeing how it is stored.

Describe a real-life scenario that illustrates the Iterator pattern and why it is useful.

Consider everyday tools that let you move through items one by one.