ktfmt

By default, ktfmt respects user-authored line breaks inside lambda bodies. This preserves the semantic structure of DSLs (like Jetpack Compose or Gradle scripts) without forcing a specific layout.

• A multi-line lambda in the source remains multi-line.
• A single-line lambda in the source remains single-line.

// Multi-line in source is preserved
App {
  SelectableCard {
    Button { Text("Click me") }
  }
}

// Single-line in source is also preserved
dependencies { implementation(libs.androidx.activity) }
val state = remember { mutableStateOf(false) }

Unlike ktlint or standard IntelliJ formatting, ktfmt is based on google-java-format and follows these principles:

1. Deterministic Output: It ignores most existing formatting. The output is independent of the input code, ensuring a single consistent style across large codebases.
2. Minimal Configuration: It does not expose many configuration options to prevent 'bikeshedding' (endless debates over minor style differences). The primary configuration is the choice between --google-style and --kotlinlang-style.
3. Column Width: ktfmt is designed to handle code that fits well within 100 columns, addressing issues where other formatters might struggle with line wrapping.

The plugin's compatibility with different IntelliJ/Android Studio versions is defined in ktfmt/gradle/libs.versions.toml using the following keys:

• intellijPlatform.pluginConfiguration.ideaVersion.sinceBuild: Sets the minimum supported version. The source code must be compatible with this build and must not reference classes introduced in later builds.
• intellijPlatform.pluginConfiguration.ideaVersion.untilBuild: Sets the maximum supported version.

If you use Homebrew, you can install the ktfmt CLI tool directly using the following command:

$ brew install ktfmt

To run and test the plugin, use the Gradle wrapper. Do not attempt to run the plugin directly from within IntelliJ.

./gradlew :idea_plugin:runIde

If you want to test the plugin against a specific local installation of IntelliJ or Android Studio instead of a Gradle-downloaded version:

1. In build.gradle.kts, set intellij.alternativeIdePath to the path of your local IDE installation.
2. Ensure the plugin is enabled in that IDE. You can find it by pressing Cmd-shift-A (macOS) and typing 'ktfmt', then looking for Preferences.

To build the website for deployment, you need to set the KTFMT_TMP_DIR and KTFMT_WEBSITE_OUTPUT_DIR environment variables before running the gulp build command. The following steps use a temporary directory for the build process.

npm install .
KTFMT_TMP_DIR=$(mktemp -d)
KTFMT_WEBSITE_OUTPUT_DIR=$KTFMT_TMP_DIR gulp build-website

# Clean up:
rm -rf "$KTFMT_TMP_DIR"

To use ktfmt directly within JetBrains IDEs:

1. Open IDE Settings (or Preferences on macOS).
2. Select Plugins and go to the Marketplace tab.
3. Search for and install the ktfmt plugin.
4. Enable it: The plugin is disabled by default. Go to File → Settings... → ktfmt Settings (or IntelliJ IDEA → Preferences → Editor → ktfmt Settings on macOS) and check Enable ktfmt.

Note: Once enabled, it replaces the standard Reformat Code action (Ctrl-Alt-L).

Sharing settings: To ensure team consistency, commit the .idea/ktfmt.xml file to your version control system.

To run the plugin on a specific version of the IDE managed by Gradle:

1. Change the intellij.version property in build.gradle.kts.
2. Comment out the alternativeIdePath property to ensure Gradle handles the download and execution.

To run the demo website for ktfmt on your local machine, install the dependencies and start the simple server using npm.

npm install .
npm run simpleserver

To build the AWS Lambda implementation of the ktfmt online formatter, run the Gradle build task for the :lambda module from the project root.

./gradlew :lambda:build

For build automation, you can integrate ktfmt using the following tools:

• Gradle: Use the ktfmt-gradle plugin from the Gradle Plugin Portal, or use Spotless with the ktfmt plugin.
• Maven: Use Spotless with the ktfmt Maven plugin.
• Pre-commit hooks: Use the implementation provided in language-formatters-pre-commit-hooks.