Including Assets - acrimi/Raven GitHub Wiki

Launch4j will handle packaging your code resources, but it's up to you to ensure your assets are also included in your release. The easiest way to do this is to set up a copy task leveraging Launch4j's outputDir property and have that task run when you need to create a build:

task copyAssets(type: Copy) {
    from project.assetsDir
    into "${buildDir}/${launch4j.outputDir}/assets"
}

Make sure you have set up your assets directory in your project level build.gradle file for this to work:

project.ext {
    assetsDir = new File(rootDir, 'assets')
}