L2.1: Loops and Arrays

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L2.1 — Loops and Arrays covers the three loop constructions in Java (while, do-while, for), their differences in condition-checking behaviour, infinite loops, and introduces arrays as fixed-size homogeneous storage with declaration, instantiation, assignment, retrieval, and the enhanced for-each loop.

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📋 At a Glance

[ ] Understand why loops exist (avoid copy-paste repetition)
[ ] Master while loop — condition checked before each iteration
[ ] Master do-while loop — condition checked after each iteration (runs at least once)
[ ] Master for loop — initialisation, condition, state change in one line
[ ] Recognise infinite loops and their causes
[ ] Understand for-loop variable scoping (declared inside = doesn't persist outside)
[ ] Know that all loops are interchangeable but each has a natural use case
[ ] Declare, instantiate, and use arrays
[ ] Use the enhanced for-each loop to iterate over arrays
[ ] Handle ArrayIndexOutOfBoundsException

1. Why Loops?

Loops allow us to repeat a block of code multiple times without copy-pasting.

Without loops: You'd need to write System.out.println("Hello"); 55 times for 55 hellos — fixed, inflexible, impossible for large counts.

With loops: A single block of code is repeated as many times as needed, and the number of repetitions can be dynamic.

Java has three loop constructions: while, do-while, and for. All three can achieve the same result — they exist because each is more natural and readable in different situations.