A demo for J2ObjC - Kotlin/Native Interop where Java code imports and calls Kotlin code, and then the Java and Kotlin code is translated by J2ObjC and Kotlin/Native, respectively.

• Kotlin and Kotlin/Native
• Java 8
• My J2ObjC Fork on the kotlin-native branch

If you use Homebrew on macOS, you can install Kotlin with brew install kotlin.

To install Kotlin/Native, you can download a copy of the release tar such as this one, untar the file, then add the untared kotlin-native-macos-$VERSION/bin to your PATH.

Before you follow the instructions below, make sure that:

• kotlinc is from your Kotlin installation (not the Kotlin/Native installation)
• kotlinc-native is from your Kotlin/Native installation
• j2objc and j2objcc are from your J2ObjC installation (built from my fork on the kotlin-native branch here)

In the project root, compile the Kotlin file with:

kotlinc-native src/com/google/kotlin/interop/KotlinSide.kt -produce framework -o ComGoogleKotlinInterop

(The framework name currently needs to be the same as the package name.)

Then, produce the JAR file that is needed by the J2ObjC step:

kotlinc src/com/google/kotlin/interop/KotlinSide.kt -include-runtime -java-parameters -d KotlinSide.jar

Now, translate the Java side with J2ObjC:

j2objc src/com/google/kotlin/interop/JavaSide.java -classpath KotlinSide.jar

Alternativley, if you are running J2ObjC from its IntelliJ project file, run the translator with the arguments [path-to-file]/JavaSide.java -classpath [path-to-file]/KotlinSide.jar

Make a symbolic link to the framework produced by kotlinc-native (this is due to how we currently make header references in the translator fork):

ln -s $PWD/ComGoogleKotlinInterop.framework com/google/kotlin/interop/

Finally, compile the translated Objective-C code and build the executable with j2objcc:

j2objcc com/google/kotlin/interop/JavaSide.m -I ./ -F ./ -framework ComGoogleKotlinInterop -rpath ./

Run the result with:

./a.out ComGoogleKotlinInteropJavaSide

The output should look like

7
15
-1
3
0

Copyright 2020 Google LLC

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

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distributed under the License is distributed on an "AS IS" BASIS,
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