Java 8 Source Compatibility

TamboUI's library modules (tamboui-core, tamboui-widgets, tamboui-toolkit, tamboui-tui, the backends, etc.) target Java 8 source compatibility so they can run on any modern JVM, including embedded scenarios. Demos and tooling are free to use newer Java. Why: dropping Java 8 here would lock out users on long-LTS deployments without their consent — and the cost of staying on Java 8 in the library is small.

What Library Code Can Use

• All Java 8 language features: lambdas, method references, streams, default/static interface methods, Optional
• Standard library APIs available in Java 8 (java.util.function, java.time, Collectors, etc.)
• Immutable data structures via Collections.unmodifiable*, Arrays.asList, builder patterns

What Library Code Must NOT Use

• var (Java 10), text blocks (Java 15), record (Java 16), sealed classes (Java 17), pattern matching for instanceof and switch
• List.of, Map.of, Set.of (Java 9) — use Collections.unmodifiableList(Arrays.asList(...)) instead
• Any java.util.* API added after Java 8 (Stream.toList, String.lines, Files.mismatch, etc.)

Demos and Tooling Are Different

• Demo modules under demos/ should use Java 21 idioms — pattern matching, records, switch expressions, var — they exist to showcase modern Java
• The tamboui-processor module and build scripts can also use newer Java if useful
• Do not let demo idioms bleed into library modules during refactors

Verifying

• ./gradlew -q assemble will fail if a library module uses a too-new feature
• ./gradlew -q javadoc must also pass before considering a change done — TamboUI treats javadoc warnings as errors