A source code generator for Kotlin data classes to automatically create a Builder class.
When annotating a Kotlin data class with @JvmBuilder
@JvmBuilder
data class Test(val foo: Int = 1, val bar: String)
The following class is generated
// Code auto-generated by JvmBuilder. Do not edit.
package com.example
import kotlin.Int
import kotlin.String
class JvmBuilder_Test {
private var foo: Int? = null
private var bar: String? = null
fun foo(foo: Int): JvmBuilder_Test {
this.foo = foo
return this
}
fun bar(bar: String): JvmBuilder_Test {
this.bar = bar
return this
}
fun build(): Test {
var result = com.example.Test(bar = this.bar!!)
result = result.copy(foo = this.foo ?: result.foo)
return result
}
}
This provides a Builder class that can be used in Java to create your Kotlin Test data class using the default values and following a Builder Pattern.
The following Java code generates a Test instance with foo = 1 (taking the 1 from the default Kotlin constructor) and bar = "bar".
new Jvm_Builder().bar("bar").build()
Gradle users should add the dependencies in their build.gradle file:
dependencies {
implementation "io.github.jffiorillo:builder-annotations:<latest_version>"
kapt "io.github.jffiorillo:builder:<latest_version>"
}
Maven users should add the dependencies in their pom.xml file:
<dependency>
<groupId>io.github.jffiorillo</groupId>
<artifactId>builder-annotations</artifactId>
<version>{latest_version}</version>
</dependency>
<dependency>
<groupId>io.github.jffiorillo</groupId>
<artifactId>builder</artifactId>
<version>{latest_version}</version>
<scope>provided</scope>
</dependency>
- In order to have a good Kotlin interoperability with Java, you can use this tool to generate automatically generate Builders for your data classes that are accessible from Java consumers.
- The time of executing the annotation processor is really slow because uses the kotlin-metadata instead of reflection.