Getting the following after creating a .app although I have java 1.8x installed

[dhowe]

<project name="Pataclysm" default="export" basedir=".">
	<target name="export">
		
		<jar destfile="tmp/app.jar" basedir="bin"/>
		
		<jarbundler dir="/Users/dhowe/Desktop/" name="Pataclysm" jvmversion="1.8" mainclass="core.Pataclysm">
			<jarfileset dir="lib">
				<include name="**/*.jar" />
			</jarfileset>
			<jarfileset dir="tmp">
				<include name="**/*.jar" />
			</jarfileset>
		</jarbundler>	
	</target>
</project>

[tofi86]

That has nothing to do with the JarBundler project.

You have the JRE browser plugin installed which does not register as Java VM on the system so apps can use it.
If you want a JVM for App usage, you have to install the JDK.

OR you can use an alternative JavaApplicationStub like mine: https://github.com/tofi86/universalJavaApplicationStub
It will also try to use the JRE browser plugin when possible...