CODEWITHSUNDEEP
javajar
bashoogzaad
bashoogzaad

Reputation: 4781

Unable to run downloaded jar from other jar

I currently have the following problem:

I have created a updater jar from which a client jar is downloaded and placed in some directory (just somewhere on the disk, not associated with the directory of the updater jar). I use the following code the run the client jar from the updater:

private void startApplication() {

    String url = getFilePath()+"client.jar";

    URL parsedURL = null;
    try {
        parsedURL = new File(url).toURI().toURL();
    } catch (MalformedURLException e) {
        e.printStackTrace();
    }

    ClassLoader loader = URLClassLoader.newInstance(new URL[]{parsedURL}, getClass().getClassLoader());
    Class<?> cl = null;
    try {
        cl = Class.forName("org.myApp.client.mainPackage.Main", true, loader);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    finally {
        loader = null;
    }

    Class<? extends Application> runClass = cl.asSubclass(Application.class);
    // Avoid Class.newInstance, for it is evil.
    Constructor<? extends Application> ctor = null;
    try {
        ctor = runClass.getConstructor();
    } catch (NoSuchMethodException | SecurityException e) {
        e.printStackTrace();
    }

    Application doRun = null;
    try {
        doRun = ctor.newInstance();
    } catch (InstantiationException | IllegalAccessException
            | IllegalArgumentException | InvocationTargetException e) {
        e.printStackTrace();
    }

    try {
        doRun.start(primaryStage);
    } catch (Exception e) {
        e.printStackTrace();
    }

}

This code seems to work, because the Main of the client.jar gets runned. However, after its Main is started, I get an exception from the client jar. The Main from the client jar tries to load a FXML file in the upper pane. This is the exception:

ClassNotFoundException: org.myApp.client.lockscreen.LockscreenController when loading a FXML file

I do not know what triggers this error. The client jar just runs as should be, when I run it standalone.

Do I need to load all classes from the client jar from the updater jar?

Any help is greatly appreciated!

Upvotes: 1

Views: 60

Answers (2)

bashoogzaad
bashoogzaad

Reputation: 4781

Everybody thanks for your help. I was able to fix it like this (thanks Jool, you will get all the credits):

I downloaded and runned the client jar, assuming it would have its own references. However, as Jool said, I had to add the director to the class path. What I did wrong, was that I added the directory, and not the Jar file. You have to add the JAR file too ! I did that with this code:

public void addPath(String s) throws Exception {

    File f = new File(s);
    URI u = f.toURI();
    URLClassLoader urlClassLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();
    Class<URLClassLoader> urlClass = URLClassLoader.class;
    Method method = urlClass.getDeclaredMethod("addURL", new Class[]{URL.class});
    method.setAccessible(true);
    method.invoke(urlClassLoader, new Object[]{u.toURL()});

}

And then I just called addPath(url) before running the client jar.

Upvotes: 3

Jool
Jool

Reputation: 1785

It is saying that the class cannot be found because it is not on your classpath.

This depends on how you build your application (Ant, Maven etc), since this determines how the location of the .jar file is known, and where the .jar file is.

If you are using an IDE, there would usually be some sort of Libraries placeholder in which you define .jars that you are dependent upon.

Upvotes: 2

Related Questions