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My build.gradle file is as following

apply plugin: 'java' sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { testCompile group: 'junit', name: 'junit', version: '4.12' compile 'io.javalin:javalin:1.3.0' compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.4' compile 'org.slf4j:slf4j-simple:1.7.25' } jar { manifest { attributes( 'Class-Path': configurations.runtime.files.collect {"$it.name"}.join(' '), 'Main-Class': 'products.ProductAPI' ) } } task stage { dependsOn 'build' dependsOn 'clean' build.mustRunAfter clean }

Trying to build a java application with gradle and deploy it to a heroku server. I have some issues on java -jar build/libs/MyApp-0.0.1.jar as it returns the following:

Exception in thread "main" java.lang.NoClassDefFoundError: io/javalin/Javalin at products.ProductAPI.main(ProductAPI.java:7) Caused by: java.lang.ClassNotFoundException: io.javalin.Javalin at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

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  • Try compile group 'io.javalin:javalin:1.3.0' Commented Mar 5, 2018 at 15:49
  • tried it, and it didn't work unfortunetely Commented Mar 5, 2018 at 16:02

1 Answer 1

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To run your app without any NoClassDefFoundError, you should have your dependencies in the runtime class path. Creating a fat jar is the simplest solution. Change your jar section like below;

jar { manifest { attributes( 'Class-Path': configurations.compile.files.collect {"$it.name"}.join(' '), 'Main-Class': 'products.ProductAPI')} from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } } }

run gradle build command and jar with dependencies will be created. Other way is to add jars to runtime class path are; with java -cp flag. (Also If your application has already a classpath folder configured, copying dependencies in this folder will add them to the classpath)

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If the dependencies are configured with implementation scope, fat jar can be created with: stackoverflow.com/a/49284432/5210117

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