How to specify a classpath when using Java Web Start

01 Oct 2023

JavaWebStart

When using Java Web Start to launch your Java applications, it’s important to specify the classpath correctly to ensure that all the required dependencies are included. The classpath tells Java where to find the necessary class files and libraries for your application to run.

Here are the steps to specify a classpath when using Java Web Start:

Step 1: Create a JNLP File

JNLP (Java Network Launch Protocol) is an XML file used by Java Web Start to launch applications. Create a JNLP file for your application (e.g., myapp.jnlp) or modify an existing one.

Step 2: Define the Resources

Inside the JNLP file, define the resources your application requires. This includes the main JAR file and any additional JAR files or libraries.

For example:

<resources>
    <jar href="myapp.jar" main="true" />
    <jar href="dependency1.jar" />
    <jar href="dependency2.jar" />
</resources>

In the above example, myapp.jar is the main JAR file, and dependency1.jar and dependency2.jar are additional JAR files.

Step 3: Specify the Classpath

To specify the classpath, you need to use the classpath attribute inside the jar element. This attribute accepts a space-separated list of file paths or URLs.

For example:

<resources>
    <jar href="myapp.jar" main="true" classpath="dependency1.jar dependency2.jar" />
</resources>

In the above example, the main JAR file myapp.jar has the classpath attribute set to dependency1.jar dependency2.jar.

Step 4: Sign the JAR Files (Optional)

If your application is using trusted resources or requires elevated permissions, you may need to sign the JAR files. This involves obtaining a code signing certificate and using tools like jarsigner or third-party tools to sign the JAR files.

Step 5: Deploy and Test

Once you have set up the JNLP file and specified the classpath, you can deploy your application to a web server or distribute it to users. Users can then launch your application using Java Web Start.

Make sure to test the deployment and ensure that the application launches successfully with all the required dependencies.

That’s it! Following these steps will allow you to specify a classpath when using Java Web Start for your Java applications. #Java #JavaWebStart