universalJavaApplicationStub

A BASH based launcher stub for Java based macOS Apps that works with both Apple's and Oracle's plist format. It is released under the MIT License.

📃 🔄 See the CHANGELOG for a Release History and feature details.

🐛 🔥 Report Issues at the GitHub Issues Page.

🤔 ❓ If you have a general question about how a feature works or would like to share an idea or a usecase for this project, then please use the GitHub Discussions Page.

Why

Whilst developing some Java Apps for Mac OS X I was facing the problem of supporting two different kinds of Java versions – the old Apple versions and the new Oracle versions.

Is there some difference, you might ask? Yes, there is!

1. The installation directory differs:

• Apple Java 1.5/1.6: /System/Library/Java/JavaVirtualMachines/ or /Library/Java/Home/bin/java
• Oracle JRE 1.7/1.8: /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/
• Oracle JDK 1.7/1.8: /System/Library/Java/JavaVirtualMachines/

2. Mac Apps built with tools designed for Apple's Java (like Apple's JarBundler or the OpenSource ANT task "Jarbundler") won't work on Macs with Oracle Java 7 and no Apple Java installed.

• This is because Apple's JavaApplicationStub only works for Apple's Java and their style to store Java properties in the Info.plist file.
• To support Oracle Java 7 you would need to built a separate App package with Oracle's ANT task "Appbundler".
• Thus you would need the user to know which Java distribution he has installed on their Mac. Not very user friendly...

3. Oracle uses a different syntax to store Java properties in the applications Info.plist file. A Java Application packaged as a Mac App with Oracle's Appbundler also needs a different JavaApplicationStub and therefore won't work on systems with Apple's old Java...

4. Starting with Mac OS X 10.10 (Yosemite), Java Apps won't open anymore if they contain the deprecated Plist dictionary Java. This isn't confirmed by Apple, but issue #9 leads to this assumption:

• Apple seems to declare the Java dictionary as deprecated and ties it to their old Apple Java 6. If you have a newer Oracle Java version installed the app won't open.
• If Java 7/8 is installed, Apple doesn't accept those java versions as suitable
• Apple prompts for JRE 6 download even before the JavaApplicationStub is executed. This is why we can't intercept at this level and need to replace the Java dictionary by a JavaX dictionary key.
• This requires to use the latest JarBundler version (see below for more details)

TL;DR: Since there is no universally working JavaApplicationStub for Java 6, 7 and above, and because Apple and Oracle really screwed things up during their Java transition phase, I was in need of a new Stub file. And well, since I can't write such a script in C, C# or whatever fancy language, I wrote it as a Bash script. And it works! The original script was inspired by Ian Roberts stackoverflow answer. Thanks, Ian!

How the script works

You don't need a native JavaApplicationStub file anymore. The Bash script needs to be executable – that's all.

The script reads JVM properties from Info.plist regardless of whether it's Apple or Oracle syntax and passes them to a exec java call like the following simplified:

# execute Java and set
# - classpath
# - splash image
# - dock icon
# - app name
# - JVM options / properties (-D)
# - JVM default options (-X)
# - main class
# - main class arguments
# - passthrough arguments from Terminal or Drag'n'Drop to Finder icon
exec "${JAVACMD}" \
    -cp "${JVMClassPath}" \
    -splash:"${ResourcesFolder}/${JVMSplashFile}" \
    -Xdock:icon="${ResourcesFolder}/${CFBundleIconFile}" \
    -Xdock:name="${CFBundleName}" \
    ${JVMOptions} \
    ${JVMDefaultOptions} \
    ${JVMMainClass} \
    ${MainArgsArr} \
    ${ArgsPassthru}

It sets the classpath, the dock icon, the AboutMenuName (as Xdock parameter) and then every JVMOptions, JVMDefaultOptions or JVMArguments found in the Info.plist file. See the table below for more supported Plist keys.

The WorkingDirectory is either retrieved from Apple's Plist key Java/WorkingDirectory or set to the JavaRoot directory within the app bundle.

The name of the main class is also retrieved from Info.plist. If no main class is found, an AppleScript error dialog is shown and the script exits with exit code 1.

There is some foo happening to determine which Java versions are installed – here's the list in which order system properties are checked:

1. System variable $JAVA_HOME

• can also be set to a relative path using the <LSEnvironment> Plist dictionary key
  • which allows for bundling a custom version of Java inside your app!

2. Highest available Java version (Java 8 trumps 7) found in one of these locations:

• /usr/libexec/java_home symlinks
• Oracle's JRE Plugin: /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java
• Symlink for old Apple Java: /Library/Java/Home/bin/java

3. If you require a specific to-the-point Java version or a minimum requirement with the Plist key JVMVersion the script will try to find a matching JDK or JRE in all of the above locations

• if multiple matching JVM's are found, the script will pick the latest (highest version number)
• starting from version 3.0 of this script you can use a special syntax in Plist key JVMVersion to specify a max requirement. See issue #51 for examples.

If none of these can be found or executed the script shows an AppleScript error dialog saying that Java needs to be installed:

Messages are localized and displayed either in English (Default), French, German or Chinese. Language contributions are very welcome! Thank you!

What you need to do

Use whichever ANT task you like:

• the opensource "JarBundler" (recommended)
  • or my JarBundler fork (deprecated)
  • both support the newly introduced and recommended JavaX dict key
• Oracle's opensource "Appbundler" (seems to be dead)
  • or infinitekind's fork

Or build the App bundle statically from scratch...

JarBundler (≥ v3.3) example

Download the latest JarBundler release from its github repo.

❗ Attention:

Using an older version of JarBundler (e.g. old JarBundler ≤ v2.3 or new JarBundler ≤ v3.2) might result in issue #9 (Mac OS X 10.10 asking to install deprecated Apple JRE 6 instead of using a newer Java version)

If you don't want to care about compatibility issues between OS X and Java versions, make sure to use the latest JarBundler version ≥ 3.3

Then place the universalJavaApplicationStub from this repo in your build resources folder and link it in your ANT task (attribute stubfile). Don't forget to set the newly introduced useJavaXKey option for compatibility:

<jarbundler
	name="Your-App"
	shortname="Your Application"
	icon="${resources.dir}/icon.icns"
	stubfile="${resources.dir}/universalJavaApplicationStub"
	useJavaXKey="true"
	... >
</jarbundler>

The ANT task will take care of all the rest... But of course you can specify more options. Please check the JarBundler docs.

You should get a fully functional Mac Application Bundle working with both Java distributions from Apple and Oracle and all Mac OS X versions.

Appbundler example

Just place the universalJavaApplicationStub from this repo in your build resources folder and link it in your ANT task (attribute executableName from infinitekind fork):

<appbundler
	name="Your-App"
	displayname="Your Application"
	icon="${resources.dir}/icon.icns"
	executableName="${resources.dir}/universalJavaApplicationStub"
	... >
</appbundler>

The ANT task will take care of all the rest... But of course you can specify more options. Please check the Appbundler docs.

You should get a fully functional Mac Application Bundle working with both Java distributions from Apple and Oracle and all Mac OS X versions.

Supported PList keys

Function	Apple PList key	Oracle PList key
App Name (Dock Name)	:CFBundleName	:CFBundleName
App Icon (Dock Icon)	:CFBundleIconFile	:CFBundleIconFile
Working Directory 🌟	:Java(X):WorkingDirectory fallback to `name.app/	not supported default: name.app/Contents/Java/
Java Min/Max★ Version Requirement	:Java(X):JVMVersion	:JVMVersion
Java ClassPath (-cp …) 🌟	:Java(X):ClassPath	:JVMClassPath
Java Main Class	:Java(X):MainClass	:JVMMainClassName
Splash Image (-splash:…)	:Java(X):SplashFile	:JVMSplashFile
Java VM Options (-X…) 🌟	:Java(X):VMOptions	:JVMDefaultOptions
-XstartOnFirstThread ★	:Java(X):StartOnMainThread	not supported
Java Properties (-D…) 🌟	:Java(X):Properties	:JVMOptions
Main Class Arguments 🌟	:Java(X):Arguments	:JVMArguments

^🌟 Variable placeholders $APP_PACKAGE, $APP_ROOT, $JAVAROOT, $USER_HOME get expanded in these contexts.

Specify min/max Java requirement

Since v3.0 (#51)

Use Java(X):JVMVersion (Apple style) or :JVMVersion (Oracle style) with the following values:

• 1.8 or 1.8* for Java 8
• 1.8+ for Java 8 or higher
• 1.7;1.8* for Java 7 or 8
• 1.8;9.0 for Java 8* up to exactly 9.0 (but not 9.0.*)
• 1.8;9.0* for Java 8* and 9.0.* but not 9.1.*

Bundle a JRE/JDK with your app

You can use the Plist key LSEnvironment to export and set the $JAVA_HOME environment variable relative to your App's root directory:

<key>LSEnvironment</key>
<dict>
    <key>JAVA_HOME</key>
    <string>Contents/Frameworks/jdk8u232-b09-jre/Contents/Home</string>
<dict>

Use a compiled binary for macOS 10.15 and above

Starting with macOS 10.15 Apple by default prevents access to Protected Resources like the user's Download, Documents or Desktop folders and shows a security dialog which the user has to accept before access is granted.

When using javax.swing.JFileChooser in your application, which supports these kinds of security dialogs (interestingly java.awt.FileDialog does not!), you should use a compiled binary of the universalJavaApplicationStub script instead of the plain bash script. See issue #85 for more details.

Starting with version 3.1.0 we provide pre-built binaries on the Releases page which are automatically compiled with shc via GitHub Actions CI.

Additionaly we recommend you set Usage Description Plist keys as described further below.

Recommended additional Plist keys

NSAppleEventsUsageDescription

Starting with Mac OS 10.14 users may be confronted with an additional system security dialog before any warning dialog of this stub is shown. See issue #77 for more details.

This happens because the warning dialogs of this launcher stub are displayed with AppleScript.

It's recommended to at least set the following Plist key in order to display a descriptive message to the user, why he should grant the app system access:

<key>NSAppleEventsUsageDescription</key>
<string>There was an error while launching the application. Please click OK to display a dialog with more information or cancel and view the syslog for details.</string>

Access to "Protected Resources"

If your app requires access to Protected Resources like the user's Download, Documents or Desktop folders, there are a couple more properties to add in your Plist file for setting a Usage Description:

• NSDownloadsFolderUsageDescription
• NSDocumentsFolderUsageDescription
• NSDesktopFolderUsageDescription
• and maybe more...

This may be extra important when using javax.swing.JFileChooser in your application. See issue #85 for more details.

Logging

Starting with version 3.0 universalJavaApplicationStub logs data to the syslog facility which can be easily accessed with the Console.app utility by searching for syslog:

Log data includes debug information of the JVM search strategy, App name, language, selected JVM, WorkingDirectory and exec call.

Missing Features

At the moment, there's no support for

• required JVM architecture (like x86_64, etc.)
• prefer JDK over JRE or vice versa

License

universalJavaApplicationStub is released under the MIT License.