Unity/Native連携/Kotlin連携

はじめに

以下を確認 Unity/Native連携/Android連携 [ｼｮｰﾄｶｯﾄ]

javaをkotlinにする場合

UnityRenkei.javaを削除し、UnityRenkei.ktを追加する

UnityRenkei.kt

package com.example.mylibrary
import android.util.Log
class UnityRenkei {
    companion object {
        @JvmStatic
        fun teststatic(flag: Boolean): Boolean {
            return flag
        }
        @JvmStatic
        fun teststrstatic(message: String): String {
            return "Static received: $message"
        }
        @JvmStatic
        fun testnumberstatic(num: Int): Int {
            return num + 10
        }
    }
    fun test(flag: Boolean): Boolean {
        return flag
    }

    fun testexec() {
        Log.i("test", "testexec")
    }
}

プロジェクト直下のbuild.gradleにbuildscriptを追加

buildscript {
    ext.kotlin_version = "1.8.10"
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:8.1.0"
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

plugins {
    id 'com.android.application' version '8.1.0' apply false
    id 'com.android.library' version '8.1.0' apply false
    id 'org.jetbrains.kotlin.android' version '1.8.10' apply false
}

mylibrary/build.gradleを以下の通り修正

plugins {
    id 'com.android.library'
    id 'org.jetbrains.kotlin.android'
}

android {
    namespace 'com.example.mylibrary'
    compileSdk 34

    defaultConfig {
        minSdk 24

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        consumerProguardFiles "consumer-rules.pro"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = "1.8"
    }
}
dependencies {
    implementation 'androidx.appcompat:appcompat:1.6.1'
    implementation 'com.google.android.material:material:1.8.0'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
}

"NoClassDefFoundError"エラーが出る場合

エラー詳細

Error Unity AndroidJavaException: java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;
Error Unity java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;

対策方法

ProjectSettingsのAndroidのCustomMainGradleTemplateをチェック

Assets/Plugins/Android/mainTemplate.gradle に以下を追加

buildscript {
    ext.kotlin_version = '1.8.0' 
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

apply plugin: 'com.android.library'
apply plugin: 'kotlin-android'
dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version" // Kotlinランタイムを追加
}