How to convert a .java or a .jar file into a Linux executable file ( without a .jar extension, which means it's not a .jar file )

Question

I have been searching for many similar posts about this but I still can't find my answer. I want to convert a .java program into a Linux executable file, without the .jar extension. How can I do it? I am trying to use Launch4j java wrapper, JWrapper, IzPack, making a .sh, making a .bat, running it using java -jar myFile.jar etc. but none of them worked. Some procedures are complicated and difficult to debug. Is there any straightforward way to convert a .java file or .jar file into a Linux executable file?

I need to pass this program as a Linux executable as a whole into another program that takes this program as an argument.

Answer 1

Let's say that you have a runnable jar named helloworld.jar

Copy the Bash script below to a file named stub.sh

#!/bin/sh
MYSELF=`which "$0" 2>/dev/null`
[ $? -gt 0 -a -f "$0" ] && MYSELF="./$0"
java=java
if test -n "$JAVA_HOME"; then
    java="$JAVA_HOME/bin/java"
fi
java_args=-Xmx1g
exec "$java" $java_args -jar $MYSELF "$@"
exit 1 

Than append the jar file to the saved script and grant the execute permission to the file resulting with the following command:

cat stub.sh helloworld.jar > helloworld.run && chmod +x helloworld.run 

That's all!

Now you can execute the app just typing helloworld.run on your shell terminal.

The script is smart enough to pass any command line parameters to the Java application transparently.

Credits: Paolo Di Tommaso

Source: https://coderwall.com/p/ssuaxa/how-to-make-a-jar-file-linux-executable

Answer 2

I found a solution, which is exactly what I want after hours of searching and trying. It is to use the gcj command in linux.

It works like gcc for C and g++ for C++ which compile C or C++ programs into executables.

First install gcj by using the terminal by typing:

sudo apt-get install gcj-jdk

After that, cd into the directory of where the .jar file is located, let's say the .jar file is myFile.jar, then do:

gcj myFile.jar -o newNameofTheFile --main=theMainClassNameofTheFile

to compile the .jar file. And it should work like an executable by just running it in the command line like this:

./newNameofTheFile

Answer 3

What you can do is make a tiny little C-program, that calls the one of the exec functions (see man 3 exec) to the "java" binary, passing "-jar", "xxx.jar" as arguments, see also Forking a new process in C++ and executing a .jar file