Here is my JBang cheatsheet which can help as a reference to code self-contained source-only Java programs with unmatched ease.
Getting started with JBang
Install JBang on Linux
curl -Ls https://sh.jbang.dev | bash -s - app setup
Run a JBang Script
jbang example.java
Create an executable JAR from a JBang script:
jbang export portable MyApp.java
Create a JBang class from a template
jbang init --template=hello helloworld.java
List of available JBang templates
jbang template list
Run a Java class
jbang helloworld.java
How to run a Java class in a JAR file
jbang jgroups-4.2.15.Final.jar --main=org.jgroups.tests.McastReceiverTest
How to run a Java class using Maven GAV coordinates
jbang org.jgroups:jgroups:5.1.9.Final --main=org.jgroups.tests.McastReceiverTest
How to run a Java code snippet:
echo "hello world" | jbang -c 'lines().forEach(s->println(s.substring(6)))`
Update JBang
To update JBang run the following command:
jbang version --update
Please note that if your current JDK is not aligned with the latest version of Java installed with JBang (see section JDK Configuration), the following error can occur during the update:
javax.net.ssl.SSLHandshakeException: Received fatal alert: handshake_failure
Configuration
Adding dependency
//DEPS log4j:log4j:1.2.17
Adding GitHub project (JBang will download the project, build it as use it as a dependency)
//DEPS https://github.com/DiUS/java-faker
Adding Managed Dependencies (BOM)
//DEPS io.quarkus:quarkus-bom:[email protected] //DEPS io.quarkus:quarkus-resteasy //DEPS io.quarkus:quarkus-smallrye-openapi
Using System properties in the comments
//DEPS org.openjfx:javafx-graphics:11.0.2:${os.detected.jfxname}
Using Environment variables in the comments
//DEPS org.openjfx:javafx-graphics:11.0.2:${env.jfxname}
Repository for dependencies (maven repository + custom repository)
//REPOS mavencentral,acme=https://maven.acme.local/maven
Finally, please note that you can also pass the dependencies as command line argument:
jbang --deps org.matheclipse:matheclipse-core:2.0.0,org.matheclipse:matheclipse-io:2.0.0 test.java
Adding file resources
//FILES resource.properties //FILES META-INF/resources/index.html=index.html
Adding a Manifest file:
//MANIFEST version=${version:unknown}
Setting Quarkus properties
//Q:CONFIG quarkus.datasource.db-kind=postgresql
Remote file expansion (JBang will download the remote file – tagged with % – and pass it as argument)
jbang CountWords.java %https://github.com/dwyl/english-words/raw/master/words.txt
Java Sources
Location of Java Sources
//SOURCES nested/*.java //SOURCES othernested/*.java
You can also pass the sources (and resources) location from the command line:
jbang --sources src/main/java --files src/main/resources script.java
JDK configuration
Setting JDK in your code
//JAVA 11 will force use of Java 11. //JAVA 13+ will require at least java 13. Java 13 or higher will be used.
Install a JDK
jbang jdk install 17
Install a JDK already available on your machine:
jbang jdk install 17 `sdk home java 17.0.4.1-tem`
Uninstall a JDK
jbang jdk uninstall 14
List available JDK
jbang jdk list
Setting default JDK
jbang jdk default 12
Debugging and JDK Settings
Debugging a Java class
jbang --debug helloworld.java
Setting java and javac options
//JAVAC_OPTIONS -source 11 //JAVA_OPTIONS -Xms128m -Xmx512m
Catalog
Install an app from the Catalog
jbang app install [email protected]/camel
List of available apps
jbang app list
