Intermediate module

Module 10: Strings, Files, and Everyday Core APIs

Strengthen the APIs you use every week in real code: strings, formatting, regex, paths, and files.

Module lessons

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Understand why Strings are immutable, how that affects performance, and when the string pool matters.

Use StringBuilder when you need to build text step by step without creating wasteful temporary strings.

Format numbers, text, and aligned output so your programs look cleaner and easier to read.

Learn a small set of regex tools for validation, search, and simple text extraction.

Work with Path and Files APIs to read, write, and inspect files in modern Java.

Parse a simple log file, count events, and produce a readable summary report.