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Kotlin is JetBrains' statically typed language for the JVM, Android, JavaScript, and native platforms, built around null safety, coroutines, and Java interop. This review covers what problems it solves over plain Java, how to build the compiler itself from source, and where it's a stronger or weaker fit than the alternatives.

Free Programming Books (Chinese) is justjavac's GitHub index of free programming books, translated manuals, and course notes in Chinese, organized under headings like AI, Go, C/C++, and version control. It's a link list, not a curriculum - entries range from full book translations to single blog posts, some flagged `:worried:` for dead links, and contribution happens only through pull requests.

Termux is an Android terminal emulator that gives you a working Linux shell environment on your phone, backed by a separate package repository that supplies familiar tools like bash, git, python, and node. The core app handles terminal emulation and UI while optional plugins add capabilities like API access, boot scripts, floating windows, and Tasker integration—you cannot mix APKs from different sources since each signs with different keys, which catches newcomers off guard. The project is actively seeking maintainers, which signals the kind of maintenance burden to expect. Android 12+ users hit real stability problems from OS-level phantom process killing, a documented gotcha that the README explicitly calls out. Installation source matters significantly: GitHub builds include a critical security fix from v0.118.0 but use an exposed test signing key (everyone can forge updates), F-Droid builds lag by days to weeks, and the Google Play version is experimental with missing functionality. The debugging story is solid—built-in log level controls and a "Report Issue" feature that bundles diagnostics automatically, which actually makes bug reports useful.

A meticulous HTTP client for the JVM, Android, and GraalVM.