Creating runnable JAR with Gradle

Question

Until now I created runnable JAR files via the Eclipse  Export     functionallity but now I switched to IntelliJ IDEA and Gradle for build automation   Some articles here suggest the  application  plugin  but this does not entirely lead to the result I expected  just a JAR  no start scripts or anything like this    How can I achieve the same result Eclipse does with the  Export     dialog

User · Answer

Here is the solution I tried with Gradle 6.7

Runnable fat Jar (with all dependent libraries copied to the jar)

task fatJar(type: Jar) {
   
    manifest {
        attributes 'Main-Class': 'com.example.gradle.App'
    }
    from {
        configurations.compile.collect { it.isDirectory() ? it : zipTree(it) }
    } with jar
    
}

Runnable jar with all dependencies copied to a directory and adding the classpath to the manifest

    def dependsDir = "${buildDir}/libs/dependencies/"
    task copyDependencies(type: Copy) {
        from configurations.compile
        into "${dependsDir}"
    }
    task createJar(dependsOn: copyDependencies, type: Jar) {
      
        manifest {
            attributes('Main-Class': 'com.example.gradle.App',
                    'Class-Path': configurations.compile.collect { 'dependencies/' + it.getName() }.join(' ')
            )
        }
        with jar
    }

How to use ?

Add the above tasks to build.gradle
Execute gradle fatJar //create fatJar
Execute gradle createJar // create jar with dependencies copied.

More details : https://jafarmlp.medium.com/a-simple-java-project-with-gradle-2c323ae0e43d

User · Answer

I checked quite some links for the solution  finally did the below mentioned steps to get it working  I am using Gradle 2 9   Make the following changes in your build gradle file     Mention plugin   apply plugin   eu appsatori fatjar   Provide the Buildscript   buildscript   repositories       jcenter      dependencies       classpath  eu appsatori gradle-fatjar-plugin 0 3       Provide the Main Class   fatJar     classifier  fat    manifest       attributes  Main-Class    my project core MyMainClass        exclude  META-INF   DSA    META-INF   RSA    META-INF   SF     Create the fatjar      gradlew clean fatjar  Run the fatjar from  build libs     java -jar MyFatJar jar

User · Answer

As others have noted  in order for a jar file to be executable  the application s entry point must be set in the Main-Class attribute of the manifest file  If the dependency class files are not collocated  then they need to be set in the Class-Path entry of the manifest file   I have tried all kinds of plugin combinations and what not for the simple task of creating an executable jar and somehow someway  include the dependencies  All plugins seem to be lacking one way or another  but finally I got it like I wanted  No mysterious scripts  not a million different mini files polluting the build directory  a pretty clean build script file  and above all  not a million foreign third party class files merged into my jar archive   The following is a copy-paste from here for your convenience     How-to  create a distribution zip file with dependency jars in subdirectory  lib and add all dependencies to Class-Path entry in the manifest file   apply plugin   java  apply plugin   java-library-distribution   repositories       mavenCentral      dependencies       compile  org apache commons commons-lang3 3 3 2        Task  distZip  added by plugin  java-library-distribution   distZip shouldRunAfter build   jar          Keep jar clean      exclude  META-INF   SF    META-INF   DSA    META-INF   RSA    META-INF   MF       manifest           attributes  Main-Class    com somepackage MainClass                       Class-Path   configurations runtime files collect    lib  it name    join                   How-to add class path             https   stackoverflow com questions 22659463 add-classpath-in-manifest-using-gradle            https   gist github com simon04 6865179     Hosted as a gist here   The result can be found in build distributions and the unzipped contents look like this      lib commons-lang3-3 3 2 jar    MyJarFile jar    Contents of MyJarFile jar META-INF MANIFEST mf      Manifest-Version  1 0    Main-Class  com somepackage MainClass    Class-Path  lib commons-lang3-3 3 2 jar

User · Answer

Both JB Nizet and Jorge B s answers are correct   In its simplest form  creating an executable JAR with Gradle is just a matter of adding the appropriate entries to the manifest   However  it s much more common to have dependencies that need to be included on the classpath  making this approach tricky in practice   The application plugin provides an alternate approach  instead of creating an executable JAR  it provides    a run task to facilitate easily running the application directly from the build an installDist task that generates a directory structure including the built JAR  all of the JARs that it depends on  and a startup script that pulls it all together into a program you can run distZip and distTar tasks that create archives containing a complete application distribution  startup scripts and JARs    A third approach is to create a so-called  fat JAR  which is an executable JAR that includes not only your component s code  but also all of its dependencies   There are a few different plugins that use this approach   I ve included links to a few that I m aware of  I m sure there are more    shadow one-jar spring-boot capsule

User · Answer

Thank you Konstantin  it worked like a charm with few nuances  For some reason  specifying main class as part of jar manifest did not quite work and it wanted the mainClassName attribute instead  Here is a snippet from build gradle that includes everything to make it work   plugins     id  java     id  com github johnrengelman shadow  version  1 2 2            apply plugin   application  apply plugin   com github johnrengelman shadow          mainClassName    com acme myapp MyClassMain              shadowJar       baseName    myapp      After running gradle shadowJar you get myapp- version -all jar in your build folder which can be run as java -jar myapp- version -all jar

User · Answer

Have you tried the  installApp  task   Does it not create a full directory with a set of start scripts   http   www gradle org docs current userguide application plugin html

User · Answer

Least effort solution for me was to make use of the gradle-shadow-plugin  Besides applying the plugin all that needs to be done is    Configure the jar task to put your Main class into manifest  jar     manifest      attributes  Main-Class    com my app Main          Run the gradle task     gradlew shadowJar   Take the app-version-all jar from build libs    And finally execute it via   java -jar app-version-all jar

User · Answer

An executable jar file is just a jar file containing a Main-Class entry in its manifest  So you just need to configure the jar task in order to add this entry in its manifest   jar       manifest           attributes  Main-Class    com foo bar MainClass            You might also need to add classpath entries in the manifest  but that would be done the same way   See http   docs oracle com javase tutorial deployment jar manifestindex html

User · Answer

You can define a jar artifact in the module settings  or project structure     Right click the module   Open module settings   Artifacts       JAR   from modules with dependencies  Set the main class    Making a jar is then as easy as clicking  Build artifact     from the Build menu  As a bonus  you can package all the dependencies into a single jar   Tested on IntelliJ IDEA 14 Ultimate

User · Answer

Configure Main Class to your Manifest  If you are using gradle project  just add the following into your build gradle jar       manifest           attributes                  Main-Class    pokerhandscorer PokerHandScorer                      Where  pokerhandscorer  is the name of the package name  and PokerHandScorer is the main class name  This creates a jar file into your  build libs jarFilename  jar  Run jar file using java -jar   path   jarFileName jar    java -jar   path   jarFileName jar

User · Answer

You can use the SpringBoot plugin   plugins     id  org springframework boot  version  2 2 2 RELEASE      Create the jar  gradle assemble   And then run it  java -jar build libs   jar   Note  your project does NOT need to be a SpringBoot project to use this plugin

[java] Creating runnable JAR with Gradle

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