Topic 3. Methods, arrays, and strings: String, StringBuilder, and text blocks

Goal: learn to break an algorithm into methods, process arrays and Unicode text, use standard operations, and check boundary data.

Lecture contents

1. Methods and parameters — A method as a separate algorithm step · Passing parameters by value · Overloading, varargs, and documentation · Example 1. Array statistics
2. Recursion and arrays — Recursion and the call stack · Arrays: length, indices, and references · Standard Arrays operations
3. Two-dimensional arrays and arguments — Two-dimensional and jagged arrays · Example 2. Rotating a matrix by 90 degrees · Command-line arguments
4. String and Unicode — String: immutability and comparison · Unicode: code units and code points · Example 3. Normalizing words
5. Building text and regular expressions — StringBuilder and building text · Text blocks and indentation · Example 4. An HTML report from table rows · Regular expressions: a brief practical introduction

Practice and review

• Practice — 3 worked examples with complete code
• Tasks — 30 variants, each with tasks at three difficulty levels
• Summary — conclusions and self-check questions