Java: Why Iterator Design Pattern is Important

With an explanation of how it is used in real world

The Iterator Pattern is a behavioral design pattern used to traverse elements of a collection (like lists, arrays, or sets) without exposing the underlying representation of the collection. It’s essential in Java and other object-oriented languages because it simplifies navigation through complex collections and promotes clean and maintainable code.

Why Code Can be Bad Without the Iterator Pattern

Imagine we have a custom collection, BookCollection, that stores books in an array. If we don't implement the Iterator Pattern, client code directly accesses the internal structure, making it tightly coupled.

public class Library {
    public static void main(String[] args) {
        BookCollection bookCollection = new BookCollection();
        bookCollection.addBook(new Book("Book A"));
        bookCollection.addBook(new Book("Book B"));
        bookCollection.addBook(new Book("Book C"));

        // Manually accessing internal structure
        for (int i = 0; i < bookCollection.size(); i++) {
            System.out.println("Book: " + bookCollection.getBookAt(i).getName());
        }
    }
}

class Book {
    private final String name;

    public Book(String name) {
        this.name = name;
    }…