IntelliJ 2018 CE下Gradle+Java8开发libGDX跨端项目的命令行问题

Hey there, let's break down your libGDX issues step by step and get your setup running smoothly with IntelliJ 2018 CE, Gradle, and Java 8.

The tools.jar error happens because JRE doesn't include development tools like tools.jar—you need to point Gradle to a full JDK 8 installation instead. Here's how to fix it:

• First, check which JVM Gradle is using: run ./gradlew -version in your project root. Look for the "JVM" line—if it says "JRE" instead of "JDK", that's the problem.
• Set JAVA_HOME to JDK 8:
  • On Windows: Open Command Prompt and run set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_XXX (replace XXX with your JDK patch version).
  • On macOS/Linux: Run export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_XXX.jdk/Contents/Home (adjust the path to your actual JDK location).
• Project-level override: For a more reliable fix, add this line to your project's gradle.properties file:

  org.gradle.java.home=/path/to/your/jdk1.8.0_XXX
  

  This ensures Gradle always uses the correct JDK for this project, regardless of system settings.

Stuck builds usually relate to cached dependencies, network issues, or unresponsive tasks. Try these steps:

• Clean and refresh dependencies: Run ./gradlew clean build --refresh-dependencies to wipe old build artifacts and force Gradle to re-download dependencies. This fixes most cache-corruption issues.
• Check network connectivity: If the build is stuck downloading dependencies, make sure your network is stable. You can also add a domestic Maven mirror to your project's root build.gradle to speed up downloads (replace the default repositories with something like):

  repositories {
      maven { url 'https://maven.aliyun.com/repository/public' }
      mavenCentral()
      google()
  }
  

• View detailed logs: Run ./gradlew desktop:debug --info to see exactly which task the build is stuck on. This might reveal if a test is hanging, a resource is locked, or a dependency is failing to resolve.
• Verify IntelliJ Gradle config: Open IntelliJ, go to File > Settings > Build, Execution, Deployment > Build Tools > Gradle. Make sure "Gradle JVM" is set to your JDK 8 installation (not JRE).

Since your 2017 setup worked, the 2018 upgrade likely changed some default configurations. Here's how to get everything aligned:

Prerequisites #

• Install Java 8 JDK (avoid newer versions—libGDX 1.x has best compatibility with Java 8).
• In IntelliJ, install the Android SDK via File > Settings > Appearance & Behavior > System Settings > Android SDK. Install at least API level 28 (libGDX 1.9.x recommends this) and the Android Build Tools.

Import & Configure the Project #

1. Import the project: Open IntelliJ, select File > Open, then choose your project's root build.gradle file. Select "Open as Project" and wait for Gradle to sync.
2. Set language levels:
   • Open File > Project Structure (or press Ctrl+Alt+Shift+S).
   • For all modules (Android, Desktop, etc.), go to Modules > [Module Name] > Sources and set "Language level" to 8 - Lambdas, type annotations etc..
3. Android module setup:
   • In Project Structure, go to Modules > Android > SDK and select your installed Android SDK.
   • Ensure the "Compile SDK version" matches the API level you installed (e.g., API 28).
4. Desktop module run configuration:
   • Go to Run > Edit Configurations, click the + button, and select "Application".
   • Set "Main class" to your desktop launcher (e.g., com.yourgame.desktop.DesktopLauncher).
   • Set "Working directory" to $PROJECT_DIR$/assets (this ensures libGDX can find your game assets).
   • Under "JRE", select your JDK 8 installation.

Verify Builds #

• First, test the desktop build via command line: ./gradlew desktop:run. If this works, the core setup is good.
• Then, run the Android configuration in IntelliJ—make sure you have an emulator or physical device connected, and that the Android SDK is properly configured.

内容的提问来源于stack exchange，提问作者John