I am migrating our enterprise applications from Maven to Gradle. I am constantly encountering the "no main manifest attribute" error when trying to run a Java JAR file generated by our new build scripts. What is the correct syntax to define the application entry point in build gradle?
3 answers
You can fix this inside your build script by explicitly defining the attributes map for the compilation task. In Gradle, you need to target the jar configuration block and inject the main class path into the manifest headers. By adding manifest { attributes 'Main-Class': 'com.example.Main' }, the compilation engine will generate the metadata directory correctly. This ensures that the runtime environment can locate the entry sequence instantly when the compiled distribution is launched.
What happens if my Gradle project uses the application plugin? Do I still need to manually configure the manifest attributes block inside the build file?
If you want to package all external libraries together with your code in Gradle, you should look into utilizing the specialized Shadow plugin instead.
Excellent tip, Cheryl. The Shadow plugin creates a highly optimized fat archive and ensures all manifest attributes are merged cleanly, preventing classpath conflicts across complex microservice architectures.
No, Douglas. If you apply the core application plugin, you just define the main class property globally in your script. The plugin automatically syncs that string to the packaging tasks, creating a fully executable distribution bundle without any extra manual metadata blocks.