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# CLAUDE.md — Java Module

This file provides guidance to Claude Code (claude.ai/code) when working with the Java module.

## Build Commands

Maven with wrapper (`./mvnw` from repo root). All commands require `-P with-java`.

```bash
# Build (skip tests)
./mvnw clean package -P with-java -DskipTests

# Install to local Maven repo
./mvnw install -P with-java -DskipTests

# Run all tests (unit + integration)
./mvnw clean verify -P with-java

# Run unit tests only
./mvnw test -P with-java

# Run integration tests only
./mvnw verify -P with-java -DskipUTs=true

# Run a single test class (use -pl to target submodule)
./mvnw test -P with-java -pl java/tsfile -Dtest=TsFileWriterTest

# Run a single test method
./mvnw test -P with-java -pl java/tsfile -Dtest=TsFileWriterTest#testWrite

# Format code (requires Java 17+ runtime)
./mvnw spotless:apply

# Check formatting
./mvnw spotless:check
```

## Module Structure

Four submodules under `java/`:

- **common** — Shared types: `TSDataType`, `ColumnCategory`, `Binary`, `BitMap`, constants
- **tsfile** — Core implementation: read/write APIs, encoding, compression, file format
- **examples** — Reference implementations for read/write operations
- **tools** — CLI utilities for TsFile inspection

## Architecture

Key packages in `java/tsfile/src/main/java/org/apache/tsfile/`:

- `write/` — Write path: `TsFileWriter`, `Tablet` (batch API), `TSRecord` (row API)
- `read/` — Read path: `TsFileReader`, `TsFileSequenceReader`, `QueryExpression`
- `encoding/` — Encoding algorithms (RLE, TS_2DIFF, GORILLA, DICTIONARY)
- `compress/` — Compression codecs (Snappy, LZ4, ZSTD, XZ)
- `file/` — File format structures (metadata, headers, footers)
- `compatibility/` — Version compatibility handling
- `parser/` — ANTLR4-generated path parser (grammar in `src/main/antlr4/`)

Code generation: FreeMarker templates in `tsfile/src/main/codegen/` generate type-specific implementations (e.g., per-datatype readers/writers) into `target/generated-sources/`.

## Code Style

- **Formatter**: Spotless with Google Java Format 1.28.0 (the project targets Java 17 bytecode)
- **Checkstyle**: Google style variant in root `checkstyle.xml`, 100 char line limit
- **Import order**: `org.apache.tsfile`, `javax`, `java`, static imports

## Testing Conventions

- **Framework**: JUnit 4
- Unit tests: `*Test.java` — run via `mvn test`
- Integration tests: `*IT.java` — run via `mvn verify`
- Tests run in random order with `reuseForks=false`

## Internationalization (i18n)

All user-facing log messages and exception messages in `java/common`, `java/tsfile`, and `java/tools` go through `org.apache.tsfile.i18n.Messages`. Hardcoded English strings in `LOGGER.*` / `LOG.*` / `logger.*` or `throw new XxxException(...)` are not allowed for new code — add an entry to `java/common/src/main/resources/org/apache/tsfile/i18n/messages.properties` and reference it via:

- `Messages.get(key)` for SLF4J patterns (containing `{}` placeholders)
- `Messages.format(key, args)` for exception patterns (containing `%1$s` positional placeholders)

Locale at runtime is chosen in this order:

1. `-Dtsfile.locale=<tag>` system property (e.g. `zh`, `zh-CN`)
2. `Locale.getDefault()`
3. English fallback (root bundle)

When adding a key, mirror it in `messages_zh.properties` with a Simplified Chinese translation. `MessagesTest` enforces key-set alignment between the two bundles — CI fails on drift.

Technical terms (class names, method names, type names, codec names like `TsFile`, `Chunk`, `Page`, `Schema`, `RLE`, `GORILLA`) are kept in English in Chinese translations.

## License Header

Every new file must include the Apache License 2.0 header at the top. For Java files, use the `/* */` block comment style. See any existing `.java` file for the exact wording.

## Git Commit

- Do NOT add `Co-Authored-By` trailer to commit messages.