A couple of years ago, I developed a small Kotlin GUI to help me rename my files in batch. I actually created it with different JVM frameworks to compare their relative merits. In any case, I didn't use it up until last week. And then, I was surprised to see that it didn't work to rename a network volume, although it had in the past. In this brief post, I aim to describe the issue and its solution. Kotlin GUI different JVM frameworks The Problem When launching the UberJAR, I couldn't see the network volumes. If I typed the path in the field, I couldn't see any sub-nodes. I searched online for a solution, and it mentioned giving the application the Local Network permissions: Settings > Privacy & Security > Local Network. I tried to add the Java SDK or the UberJAR to the list, but I didn’t find a way. Local Network Settings > Privacy & Security > Local Network The Solution The solution is straightforward: create a regular macOS app from the UberJAR. At its simplest, a macOS app is only a folder with a specific structure. You could replicate it by hand, but I'm lazy, and there are tools for this. jpackage is such a tool. jpackage is one of the tools I learned about, am ecstatic about, used once, and forgot until the next time. Add one to the counter. folder with a specific structure jpackage jpackage I naively used jpackagelike this at first: jpackage jpackage \                                                      
  --type app-image \                                  #1
  --input target \                                    #2
  --name RenamerSwing \                               #3
  --main-jar renamer-swing-1.0-SNAPSHOT.jar           #4 jpackage \                                                      
  --type app-image \                                  #1
  --input target \                                    #2
  --name RenamerSwing \                               #3
  --main-jar renamer-swing-1.0-SNAPSHOT.jar           #4 Set value
Folder to include
Name of the app
Path to the UberJAR Set value Folder to include Name of the app Path to the UberJAR It works and generates a macOS app. We can launch the resulting app, and the OS asks whether you want to allow Local Network access. Done. However, jpackage copies the whole target folder content into the app. It includes not only the original JAR, classes, but also the rest of the content. jpackage target Improving the Build I decided to improve the Maven build instead of calling jpackagemanually. jpackage The first step is to move the UberJAR to an empty folder, so that we can setjpackage's input. jpackage input <plugin>
    <artifactId>maven-resources-plugin</artifactId>
    <version>3.3.1</version>
    <executions>
        <execution>
            <id>copy-jar-for-jpackage</id>
            <phase>package</phase>
            <goals>
                <goal>copy-resources</goal>
            </goals>
            <configuration>
                <outputDirectory>${project.build.directory}/jpackage-input</outputDirectory>
                <resources>
                    <resource>
                        <directory>${project.build.directory}</directory>
                        <includes>
                            <include>${project.build.finalName}.jar</include>
                        </includes>
                    </resource>
                </resources>
            </configuration>
        </execution>
    </executions>
</plugin> <plugin>
    <artifactId>maven-resources-plugin</artifactId>
    <version>3.3.1</version>
    <executions>
        <execution>
            <id>copy-jar-for-jpackage</id>
            <phase>package</phase>
            <goals>
                <goal>copy-resources</goal>
            </goals>
            <configuration>
                <outputDirectory>${project.build.directory}/jpackage-input</outputDirectory>
                <resources>
                    <resource>
                        <directory>${project.build.directory}</directory>
                        <includes>
                            <include>${project.build.finalName}.jar</include>
                        </includes>
                    </resource>
                </resources>
            </configuration>
        </execution>
    </executions>
</plugin> The next step is actually to find a Maven plugin that wraps jpackage. I found org.panteleyev:jpackage-maven-plugin. Here's how to use it: jpackage org.panteleyev:jpackage-maven-plugin <plugin>
    <groupId>org.panteleyev</groupId>
    <artifactId>jpackage-maven-plugin</artifactId>
    <version>1.6.5</version>
    <configuration>
        <name>RenamerSwing</name>                     
        <appVersion>${project.version}</appVersion>
        <vendor>Nicolas Fränkel</vendor>
        <destination>target</destination>
        <input>target/jpackage-input</input>          
        <mainJar>${project.build.finalName}.jar</mainJar> 
        <mainClass>${main.class}</mainClass>
        <type>APP_IMAGE</type>                        
    </configuration>
    <executions>
        <execution>
            <id>jpackage</id>
            <phase>package</phase>
            <goals>
                <goal>jpackage</goal>
            </goals>
        </execution>
    </executions>
</plugin> <plugin>
    <groupId>org.panteleyev</groupId>
    <artifactId>jpackage-maven-plugin</artifactId>
    <version>1.6.5</version>
    <configuration>
        <name>RenamerSwing</name>                     
        <appVersion>${project.version}</appVersion>
        <vendor>Nicolas Fränkel</vendor>
        <destination>target</destination>
        <input>target/jpackage-input</input>          
        <mainJar>${project.build.finalName}.jar</mainJar> 
        <mainClass>${main.class}</mainClass>
        <type>APP_IMAGE</type>                        
    </configuration>
    <executions>
        <execution>
            <id>jpackage</id>
            <phase>package</phase>
            <goals>
                <goal>jpackage</goal>
            </goals>
        </execution>
    </executions>
</plugin> App's name
Point to the folder created in the previous step
Path to the main JAR
Set value App's name Point to the folder created in the previous step Path to the main JAR Set value Note that the parameters mimic the command line options. Finishing Touches There are two finishing touches: the version and the app's size. Let's start with the version. The above configuration uses ${project.version}. The build fails if it's suffixed with -SNAPSHOT, as a Mac app version must follow the pattern major.minor.bugfix. To fix this, we can leverage the build-helper-maven-plugin. It offers several goals, including parse-versionthat destructures Maven's version into several properties. ${project.version} -SNAPSHOT major.minor.bugfix build-helper-maven-plugin parse-version <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>3.6.0</version>
    <executions>
        <execution>
            <id>parse-version</id>
            <phase>initialize</phase>
            <goals>
                <goal>parse-version</goal>
            </goals>
        </execution>
    </executions>
</plugin> <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>3.6.0</version>
    <executions>
        <execution>
            <id>parse-version</id>
            <phase>initialize</phase>
            <goals>
                <goal>parse-version</goal>
            </goals>
        </execution>
    </executions>
</plugin> We can replace the version's line with: <appVersion>${parsedVersion.majorVersion}.${parsedVersion.minorVersion}.${parsedVersion.incrementalVersion}</appVersion> <appVersion>${parsedVersion.majorVersion}.${parsedVersion.minorVersion}.${parsedVersion.incrementalVersion}</appVersion> The second improvement is the final app size. The above configuration yields a 160MB app on my machine. Not exactly concerning for a JVM-based app, but not great either. On the good side, jpackage leverages jlink underneath; jlink creates a custom JRE. The app is self-contained. jpackage jlink jlink jpackageuses all configured modules, or all by default. On the not-so-good side, we didn't configure any. By just adding the  necessary modules, we can cut the app size by half, down to 82MB. jpackage <plugin>
    <groupId>org.panteleyev</groupId>
    <artifactId>jpackage-maven-plugin</artifactId>
    <version>1.6.5</version>
    <configuration>
        <name>RenamerSwing</name>
        <appVersion>${parsedVersion.majorVersion}.${parsedVersion.minorVersion}.${parsedVersion.incrementalVersion}</appVersion>
        <vendor>ch.frankel.blog</vendor>
        <destination>target</destination>
        <input>target/jpackage-input</input>
        <mainJar>${project.build.finalName}.jar</mainJar>
        <mainClass>${main.class}</mainClass>
        <type>APP_IMAGE</type>
        <addModules>
            <addModule>java.base</addModule>
            <addModule>java.desktop</addModule>
            <addModule>java.logging</addModule>
        </addModules>
    </configuration> <plugin>
    <groupId>org.panteleyev</groupId>
    <artifactId>jpackage-maven-plugin</artifactId>
    <version>1.6.5</version>
    <configuration>
        <name>RenamerSwing</name>
        <appVersion>${parsedVersion.majorVersion}.${parsedVersion.minorVersion}.${parsedVersion.incrementalVersion}</appVersion>
        <vendor>ch.frankel.blog</vendor>
        <destination>target</destination>
        <input>target/jpackage-input</input>
        <mainJar>${project.build.finalName}.jar</mainJar>
        <mainClass>${main.class}</mainClass>
        <type>APP_IMAGE</type>
        <addModules>
            <addModule>java.base</addModule>
            <addModule>java.desktop</addModule>
            <addModule>java.logging</addModule>
        </addModules>
    </configuration> At this point, you can move the app to your Mac's Applications folder. You can also customize it further with icons, etc. As for me, it's good enough for my purposes. Applications Conclusion In this post, we started with an UberJAR unable to rename files on remote volumes because of the current macOS security model. To make it  work, we wrapped the UberJAR in a native macOS app. Then, we improved the situation with explicit modules by cutting the size in half. The complete source code for this post can be found on GitHub: https://github.com/ajavageek/renamer-swing?embedable=true https://github.com/ajavageek/renamer-swing?embedable=true To go further: To go further: Controlling app access to files in macOS
The Anatomy of a macOS App
jpackage Controlling app access to files in macOS Controlling app access to files in macOS The Anatomy of a macOS App The Anatomy of a macOS App jpackage jpackage Originally published at A Java Geek on January 25th, 2025 Originally published at A Java Geek on January 25th, 2025 A Java Geek

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