Is it reasonable to assume Jar Launcher is set up to run jar files from Finder on OS X 10.5+

java

I have a jar file containing a swing application that needs to run on Windows, OS X and Linux. At the moment, Windows users are launching it from explorer, and Linux/OS X users are running a shell script to launch the jar.

However, I suspect the shell script is probably not necessary in OS X. I don't own an OS X machine myself, but Wikipedia says that Jar Launcher will run the jar file when it's double clicked.

Is it reasonable to assume this is always present on an OS X system with 10.5 or above?

Best Answer

The Apple supplied java implementation comes installed with Mac OS 10.5 and 10.6 and .jar files are associated with the jar launcher application. As long as the java application starts right into a swing interface it should open without any problems.

On Mac OS 10.7 Lion however the java runtime is not installed by default and users trying to launch .jar files will be greeted with a dialog asking them to install java to continue (which requires admin privileges).

Officially the apple supplied java runtime is depreciated so you can't count on it working in any future version of mac os x

Related Solutions

How to launch jar the same way Jar Launcher does

The problem is that you need to specify the class paths with the cp option to java and the library paths with the D option. The Minecraft launcher under /Applications handles this if you have a default install. If you want to run the default configuration from the commandline, just run something like the following with the memory values of your choosing:

java -Xmx2048M -Xms512M -jar \
/Applications/Minecraft.app/Contents/Resources/Java/MinecraftLauncher.jar

Here's an example of how I run Minecraft from the command-line for ad-hoc mode. I put the following in a script, name it and run it by name:

MCHOME="$HOME/Library/Application Support/minecraft/bin"
CP="$MCHOME/minecraft.jar:$MCHOME/lwjgl.jar:$MCHOME/lwjgl_util.jar:$MCHOME/jinput.jar"

java -Xmx2048M -Xms512M -cp "$CP" \
    -Djava.library.path="$MCHOME/natives" \
    net.minecraft.client.Minecraft

MacOS – How to run a jar when I double-click it

You can prepend a short script to the .jar to make it executable via double click. In Terminal do the following:

$ cat > header-template <<"EOF"
#!/bin/sh

exec java -jar $0 "$@" > /dev/null

EOF
$ cat header-template "System FRONT.jar" > executable_app
$ chmod +x executable_app

Double-clicking executable_app should now launch the application.

Why does this work in the first place? Well, a .jar is just a .zip archive which gets unpacked and executed by java. And the zip format allows to prepend additional stuff in front of the actual archive. Any zip unarchiver skips this part until it finds the start of the archive (indicated by PK...).

Best Answer

Related Solutions

How to launch jar the same way Jar Launcher does

MacOS – How to run a jar when I double-click it

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