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Java Swing Maven - How to load ImageIcon in jar file

Here is my current directory structure (contained inside a connect4 directory):

├── pom.xml
├── src
│   ├── main
│   │   ├── java
│   │   │   └── com
│   │   │       └── dv
│   │   │           └── app
│   │   │               ├── App.java
│   │   │               ├── Board.java
│   │   │               
|   |   |               
│   │   │               
│   │   └── resources
│   │       ├── red-chip.png
│   │       
│   └── test
│       ...            
|                     
└── target
    ├── classes/com/dv/app/*.class

Essentially from Board.java, I am trying to access red-chip.png.

I tried many variations for this to work, right now I just have:

ImageIcon redChip = new ImageIcon("red-chip.png");

I tried changing up the path to use /resources, used the getResource function, but nothing seemed to work.

When I generate the jar using mvn package and run the jar file, it does not show the image.

I perform unzip -l <jar file> and see that my red-chip.png has been moved to the root directory for some reason.

  Length      Date    Time    Name
---------  ---------- -----   ----
      126  2019-05-30 20:03   META-INF/MANIFEST.MF
        0  2019-05-30 20:03   META-INF/
        0  2019-05-30 19:19   com/
        0  2019-05-30 19:19   com/dv/
        0  2019-05-30 19:20   com/dv/app/
        0  2019-05-30 20:03   META-INF/maven/
        0  2019-05-30 20:03   META-INF/maven/com.dv.app/
        0  2019-05-30 20:03   META-INF/maven/com.dv.app/connect4/
     4190  2019-05-30 19:20   com/dv/app/App.class
     4975  2019-05-30 19:20   com/dv/app/Board.class
      110  2019-05-29 20:29   META-INF/maven/com.dv.app/connect4/pom.properties
     7856  2019-05-30 19:32   red-chip.png

Here is my pom.xml. Main thing to look at is the build jar plugin.

(removed useless stuff like artifactID, etc)

<project xmlns="...">
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.1.0</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>lib/</classpathPrefix>
                            <mainClass>com.dv.app.App</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

So my questions are as follows:

  1. What is the proper way to reference my png file so it will be visible in the jar?

  2. Why was the png file located in the root in the jar?

Solution

  • If you need to load image as an icon for application your code should be like this. This will set the icon for your application.

    this.setIconImage(new ImageIcon(getClass().getResource("/red-chip.png")).getImage());

    If you need to use setIcon method, you can use

    ImageIcon IC = new ImageIcon(getClass().getResource("/red-chip.png"));