KotlinPoet

KotlinPoet is a Kotlin and Java API for generating .kt source files.

Source file generation can be useful when doing things such as annotation processing or interacting with metadata files (e.g., database schemas, protocol formats). By generating code, you eliminate the need to write boilerplate while also keeping a single source of truth for the metadata.

Example

Here’s a HelloWorld file:

class Greeter(val name: String) {
  fun greet() {
    println("""Hello, $name""")
  }
}

fun main(vararg args: String) {
  Greeter(args[0]).greet()
}

And this is the code to generate it with KotlinPoet:

val greeterClass = ClassName("", "Greeter")
val file = FileSpec.builder("", "HelloWorld")
  .addType(
    TypeSpec.classBuilder("Greeter")
      .primaryConstructor(
        FunSpec.constructorBuilder()
          .addParameter("name", String::class)
          .build()
      )
      .addProperty(
        PropertySpec.builder("name", String::class)
          .initializer("name")
          .build()
      )
      .addFunction(
        FunSpec.builder("greet")
          .addStatement("println(%P)", "Hello, \$name")
          .build()
      )
      .build()
  )
  .addFunction(
    FunSpec.builder("main")
      .addParameter("args", String::class, VARARG)
      .addStatement("%T(args[0]).greet()", greeterClass)
      .build()
  )
  .build()

file.writeTo(System.out)

The KDoc catalogs the complete KotlinPoet API, which is inspired by JavaPoet.

Note: In order to maximize portability, KotlinPoet generates code with explicit visibility modifiers. This ensures compatibility with both standard Kotlin projects as well as projects using explicit API mode. Examples in the documentation omit those modifiers for brevity.

Download

Download the latest .jar or depend via Maven:

<dependency>
  <groupId>com.squareup</groupId>
  <artifactId>kotlinpoet-jvm</artifactId>
  <version>[version]</version>
</dependency>

or Gradle:

implementation("com.squareup:kotlinpoet:[version]")

Snapshots of the development version are available in Sonatype’s snapshots repository.

License

Copyright 2017 Square, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.