URLClassLoader - loading classes inside of JAR archives

Hi. I'm trying to load get an instance of a class inside of a JAR file. I have:
          try
               URLClassLoader urlcl = new URLClassLoader(new URL[] { new URL("file://C:/Documents and Settings/Owner/My Documents/Eclipse Java IDE Work/temp/test.jar") });
               Applet clientClass = (Applet)urlcl.loadClass("myclass").newInstance();
               clientClass.setStub(new ClientStub());
          catch(Exception e) { e.printStackTrace(); }Problem is, everytime I try to run it, I get:
java.lang.ClassNotFoundException: client
     at java.net.URLClassLoader$1.run(Unknown Source)
     at java.security.AccessController.doPrivileged(Native Method)
     at java.net.URLClassLoader.findClass(Unknown Source)
     at java.lang.ClassLoader.loadClass(Unknown Source)
     at java.lang.ClassLoader.loadClass(Unknown Source)Any suggestions?
And yes, I can extract and view the file manually. Thanks.

new File("C:/Documents and Settings/Owner/My Documents/Eclipse Java IDE Work/temp/test.jar").toURL()?Then I have to conclude the JAR file is wrong. Can you show the relevant part of jar tvf test.jar?

Similar Messages

JRE doesn't find the main class inside a JAR archive file

Hello everybody,
I've written a small application in Java, using NetBeans. Running my application inside NetBeans works fine, but I can't run it from the console or by double clicking the jar file.
Running it from the console I get the following error message:
java -jar TestApplication.jar
Exception in thread "main" java.lang.NoClassDefFoundError: tst.Benchmark
   at gnu.java.lang.MainThread.run(libgcj.so.81)
Caused by: java.lang.ClassNotFoundException: tst.Benchmark not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:TestApplication.jar], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
   at java.net.URLClassLoader.findClass(libgcj.so.81)
   at gnu.gcj.runtime.SystemClassLoader.findClass(libgcj.so.81)
   at java.lang.ClassLoader.loadClass(libgcj.so.81)
   at java.lang.ClassLoader.loadClass(libgcj.so.81)
   at gnu.java.lang.MainThread.run(libgcj.so.81)I know that these errors often come when the class path is not set in the right way, and using a single java file, you can fix this by passing the parameter "-cp ."
I tried this with the jar file but it does not work and using "-cp TestApplication.jar tst/Benchmark" didn't work either.
Inside the jar file I have the META-INF Folder and a "tst" Folder which contains all my class files. And I've set tst.Benchmark as the main class, this also stands in the manifest file correctly.
Do you have any ideas what could be wrong?
Greetings JavanianGuy

This line
at gnu.java.lang.MainThread.run(libgcj.so.81)says that you're using GNU's Java, not Sun's Java. They are not the same. GNU Java is incomplete.
You'll need to ask this question at the GNU Java site.
Recommendation: Use Sun's Java

Can I refer to a file insider a .JAR archive with an instance of File?

Hi,
I was wondering if it is possible to refer to a file stored inside a .JAR file just as if it was on a regular folder by using an instance of the java.io.File class. Otherwise, how can one do that?
Essencially what I need is to check if a particular class file is contained inside a .JAR archive.
Best regards,
Norberto

http://java.sun.com/j2se/1.4.2/docs/api/java/util/jar/JarFile.html
See the entries() method to get a list of everything in the jar file. Most of the time the only thing you would want to do with a File is read the bytes from it, which you can do easily using the JarFile class.

Class.forname - Unable to load class if two jars with same package name

class.forname - Unable to load class if two jars contains same package name exists in classpath.
JVM is stopping search for class one it finds the package name in the jar file that is ahead in classpath,
JVM is not continuing search in the remaining jar files.
For this , I put the jar file that contained class ahead of of ther jar file containing same package name, then it worked.
Is this a JVM bug ? (JDK 1.5)

I reported as bug to sun. I got auto email, looks they have not assigned any Bug ID so far.

Dynamic class loading problem using unknown JAR archive and directory names

I read the following article, which enlightened me a lot:
Ted Neward: Understanding Class.forName().
However, it took me some while to understand that my problem is the other way around:
I know the name of the class, I know the name of the method,
but my program/JVM does not know where to load the classes from.
Shortly, my problem is that the server engine that I am writing
uses two different versions of the same library.
So I am trying out the following solution:
My program is named TestClassPathMain.java
Assume the two libraries are named JAR1.jar and JAR2.jar
and the class/instance method that should
be exposed to TestClassPathMain.java by them is named
TestClass1.testMethod().
As long as I was depending on just one library,
I put JAR1.jar in the classpath before starting java,
and I was happy for a while.
At the moment I got the need to use another version of
TestClass1.testMethod() packaged in JAR2.jar,
a call would always access JAR1.jar's
TestClass1.testMethod().
I then decided to remove JAR1.jar from the classpath,
and programmatically define two separate ClassLoaders, one for use
with JAR1.jar and the other for use with JAR2.jar.
However, the problem is only partly solved.
Please refer to the enclosed code for details.
(The code in the JAR1.jar/JAR2.jar is extremely simple,
it just tells (by hardcoding) the name of the jar it is packaged in
and instantiates another class packaged in the same jar using
the "new" operator and calls a method on it. I don't enclose it.)
The TestClassPathMain.java/UC1.java/UC2.java code suite was
successfully compiled with an arbitrary of JAR1 or JAR2 in the classpath,
however removed from the classpath at runtime.
(I know that this could have been done (more elegantly...?) by producing an Interface,
but I think the main problem principle is still untouched by this potential lack of elegancy(?))
1) This problem should not be unknown to you experts out there,
how is it generally and/or most elegantly solved?
The "*** UC2: Variant 2" is the solution I would like best, had it only worked.
2) And why arent "*** UC2: Variant 2" and
"*** static UC2: Variant 2" working,
while "*** Main: Variant 2" is?
3) And a mal-apropos:
Why can't I catch the NoClassDefFoundError?
The output:
*** Main: Variant 1 JAR 1 ***:
Entering TestClass1.testMethod() packaged in JAR1.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR1.jar
*** Main: Variant 1 JAR 2 ***:
Entering TestClass1.testMethod() packaged in JAR2.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR2.jar
*** Main: Variant 2 JAR 1 ***:
Entering TestClass1.testMethod() packaged in JAR1.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR1.jar
*** Main: Variant 2 JAR 2 ***:
Entering TestClass1.testMethod() packaged in JAR2.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR2.jar
*** UC1: Variant 1 JAR 1 ***:
Entering TestClass1.testMethod() packaged in JAR1.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR1.jar
*** UC1: Variant 1 JAR 2 ***:
Entering TestClass1.testMethod() packaged in JAR2.jar
About to instantiate TestClass2 with the new operator
About to call TestClass2.testMethod()
Entering TestClass2.testMethod() packaged in JAR2.jar
*** static UC2: Variant 2 JAR 1 ***:
Exception in thread "main" java.lang.NoClassDefFoundError: TestClass1
        at UC2.runFromJarVariant2_static(UC2.java:56)
        at TestClassPathMain.main(TestClassPathMain.java:52)
TestClassPathMain.java
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
public class TestClassPathMain {
    public static void main(final String args[]) throws MalformedURLException, ClassNotFoundException, InstantiationException, SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
            // Commented out because I cannot catch the NoClassDefFoundError.
            // Why?
            try {
                final TestClass1 testClass1 = new TestClass1();
                System.out.println(
                    "\nThe class TestClass1 is of some unexplicable reason available." +
                    "\nFor the purpose of the test, it shouldn't have been!" +
                    "\nExiting");
                System.exit(1);
            } catch (NoClassDefFoundError e) {
                System.out.println("\nPositively confirmed that the class TestClass1 is not available:\n" + e);
                System.out.println("\n\nREADY FOR THE TEST: ...");
            // Works fine
            System.out.println("\n*** Main: Variant 1 JAR 1 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** Main: Variant 1 JAR 2 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Works fine
            System.out.println("\n*** Main: Variant 2 JAR 1 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** Main: Variant 2 JAR 2 ***:");
            runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Works fine
            final UC1 uc1 = new UC1();
            System.out.println("\n*** UC1: Variant 1 JAR 1 ***:");
            uc1.runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** UC1: Variant 1 JAR 2 ***:");
            uc1.runFromJarVariant1("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Crashes
            System.out.println("\n*** static UC2: Variant 2 JAR 1 ***:");
            UC2.runFromJarVariant2_static("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** static UC2: Variant 2 JAR 2 ***:");
            UC2.runFromJarVariant2_static("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
            // Crashes
            final UC2 uc2 = new UC2();
            System.out.println("\n*** UC2: Variant 2 JAR 1 ***:");
            uc2.runFromJarVariant2("file:/W:/java/eclipse/workspaces/simped_test/CP1/JAR1.jar");
            System.out.println("\n*** UC2: Variant 2 JAR 2 ***:");
            uc2.runFromJarVariant2("file:/W:/java/eclipse/workspaces/simped_test/CP2/JAR2.jar");
    private static void runFromJarVariant1(final String jarFileURL)
        throws MalformedURLException,
               ClassNotFoundException,
               InstantiationException,
               IllegalArgumentException,
               IllegalAccessException,
               InvocationTargetException,
               SecurityException,
               NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final Object testClass1 = clazz.newInstance();
        final Method testMethod1 = clazz.getMethod("testMethod", null);
        testMethod1.invoke(testClass1, null);
    private static void runFromJarVariant2(final String jarFileURL)
        throws MalformedURLException,
               ClassNotFoundException,
               InstantiationException,
               IllegalArgumentException,
               IllegalAccessException,
               InvocationTargetException,
               SecurityException,
               NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final TestClass1 testClass1 = new TestClass1();
        testClass1.testMethod();
UC1.java
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
public class UC1 {
    public void runFromJarVariant1(final String jarFileURL)
        throws MalformedURLException,
               ClassNotFoundException,
               InstantiationException,
               IllegalArgumentException,
               IllegalAccessException,
               InvocationTargetException,
               SecurityException,
               NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final Object testClass1 = clazz.newInstance();
        final Method testMethod1 = clazz.getMethod("testMethod", null);
        testMethod1.invoke(testClass1, null);
UC2.java
import java.lang.reflect.InvocationTargetException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
public class UC2 {
    public void runFromJarVariant2(final String jarFileURL)
    throws MalformedURLException,
           ClassNotFoundException,
           InstantiationException,
           IllegalArgumentException,
           IllegalAccessException,
           InvocationTargetException,
           SecurityException,
           NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final TestClass1 testClass1 = new TestClass1();
        testClass1.testMethod();
     * Identic to the "runFromJarVariant2" method,
     * except that it is static
    public static void runFromJarVariant2_static(final String jarFileURL)
    throws MalformedURLException,
           ClassNotFoundException,
           InstantiationException,
           IllegalArgumentException,
           IllegalAccessException,
           InvocationTargetException,
           SecurityException,
           NoSuchMethodException {
        final URL url = new URL(jarFileURL);
        final URLClassLoader cl =
            new URLClassLoader(new URL[]{url},
                               Thread.currentThread().getContextClassLoader());
        final Class clazz = cl.loadClass("TestClass1");
        final TestClass1 testClass1 = new TestClass1();
        testClass1.testMethod();
}

2. i need to load the class to the same JVM (i.e. to
the same environment) of the current running
aplication, so that when the loaded class is run, it
would be able to invoke methods on it!!!
ClassLoader(s) do this. Try the URLClassLoader.
(I was talking about relatively esoteric "security"
issues when I mentioned the stuff about Class objects
"scope".) You might use the URLClassLoader kind of
like this.
Pseudo-code follows:
// setup the class loader
URL[] urls = new URL[1];
urls[0] = new URL("/path/to/dynamic/classes");
URLClassLoader ucl = new URLClassLoader(urls);
// load a class & use make an object with the default constructor
Object tmp = ucl.loadClass("dynamic.class.name").newInstance();
// Cast the object to a know interface so that you can use it.
// This may be used to further determine which interface to cast
// the class to. Or it may simply be the interface to which all
// dynamic classes have to conform in your program.
InterfaceImplementedByDynamicClass loadedObj =
    (InterfaceImplementedByDynamicClass)tmp;It's really not as hard as it sounds, just write a little test of
this and you will see how it works.

Call class inside a jar file??

Hello group,
I have a class with a main mathod and this class is inside a .jar file. This jar file reside under my
web-inf\lib or class-path directory in my application at Weblogic Server.
How can I call this class by command line?
I have to create a cliente to do it?
Is it possible? IÂ´m having problems because the weblogic server is using the jar file at the same time that I trying use it calling by command line.
Where can I find more information?
Message was edited by:
Denimar

Authcloud9981 wrote:
Hi I have an executible JAR file that I can call from command line by using the command - "java -jar file.jar".
Is there a way for me to call this JAR file inside a Java class in another Java Program?There can be more going on in a jar than just as a container for classes.
The manifest defines the behavior. So to replicate the behavior you must do exactly that.
As an example of that.
[http://java.sun.com/developer/Books/javaprogramming/JAR/basics/manifest.html#download]
Additionally by running it in your application you must consider what the scope of that is. If you just load the classes directly then they will be in the system class loader and thus cannot be unloaded. Using a class loader solves that.

Is it possible to load classes from a jar file

Using ClassLoader is it possible to load the classes from a jar file?

URL[] u = new URL[1] ;
u[0] = new URL( "file://" + jarLocation + jarFileName + "/" );
URLClassLoader jLoader = new URLClassLoader( u );
Object clsName = jLoader.loadClass( clsList.elementAt(i).toString() ).newInstance();
I get this error message.
java.lang.ClassNotFoundException: ExceptionTestCase
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
// "file://" + fileLocation + fileName + "/" This works fine from a browser.
Is there anything I am missing? Thanks for the reply.

Loading images inside applet JAR

Hi
This is my issue: I have an applet which contains images inside the applet JAR. I want to display these images in my applet, but apparently due to browser access restrictions, I'm not allowed.
My first code was like this:
//security restrictions on browsers do not allow getResource
ImageIO.read(MyClass.class.getResource("imgs/img.png"));
//getResourceAsStream should be allowed by browsers
ImageIO.read(MyClass.class.getResourceAsStream("imgs/img.png"));Both lines work when I execute the applet locally (command line / programming IDE), but when I deploy it to my web server, the resource "imgs/img.png" becomes a relative URL to my web application context (like /webcontext/MyClass/imgs/img.png). It works locally because the call to getResource returns a URL object with "file:" protocol, but I need it to look for my images bundled inside the JAR, not web hosted images.
I need to avoid making the applet look for these images as a web resource... how can I do it?
Thanks!

dev@java wrote:
warnerja wrote:
I'm not convinced the code you posted wouldn't work, but since this is an applet, you have access to the Applet class. Check out the Applet.getImage method in conjunction with Applet.getCodeBase.
[http://java.sun.com/javase/6/docs/api/java/applet/Applet.html]
getCodeBase returns my web context, like http://myhost.com/mycontext/ , so it is pretty much the same as above.
Thanks for your replyThat is the way to load resources though. Hence back to my earlier statement about not being convinced it would not work, with this addition: It should work, assuming you actually do have the resources properly located with the web app, whether they be in a jar, or loose files relative to where the web app is. My guess at this point is that they are not.

URLClassLoader loading class from jarB, which uses classes from jarC

Hi, here's my problem:
I have a classA in executable jarA.
This uses URLClassLoader to load classB from jarB. So far so good.
But classB uses classC, which lives in jarC. jarC is specified in the Class-Path of the manifest in jarB. But classB gets a ClassNotFound exception when it tries to use classC.
The situation I want to achieve looks like this (sorry for the bad art; it's almost impossible to make it look better because sun strips out extra spaces):
jarA:
classA-----> URLClassLoader(jarB).loadClass(classB)
jarB:
Class-Path jarC
classB------> new classC
jarC:
classC
My expectation was that URLClassLoader would automatically be used to load all the classes that classB uses, and that it would extend its classpath by the classpath specified in the manifest of jarB, just like the default classloader does. Anyone know what I'm doing wrong?
When I do the following, i.e. use only the default classloader, everything works fine. Unfortunately I won't know where jarB is until runtime, so I can't actually do this:
jarA:
Class-Path jarC
classA-----> new classB
jarB:
Class-Path jarC
classB------> new classC
jarC:
classC
thanks alot
j

Actually, there is definitely a way to make this work. A plugin engine has to handle this in order for plugins loaded by separate loaders to be able to share class instances with one another (dependency). My engine does static runtime plugin dependency resolution, which means it parsers every plugin's config file, then after all plugins are in the "registry" it goes back and resolves all dependencies. How it does this is that each PluginClassLoader keeps a list of "dependent" classloaders. So, if the engine finds plugin A, B, and C, and B depends on C (declares this in its config file), the engine creates 3 class loaders (custom loader called PluginClassLoader), one for each plugin. This is done so that the plugin can be unloaded or reloaded at runtime without having to shut the application down. Now, since B depends on C, when plugin B code requests a class found in C, the JVM first asks B's loader to find the class. The "normal" delegation model of Java is for B's loader to first look in the parent hierarchy, then in its own classpath. The problem with this approach is that in order to support reloadable and unloadable plugins, you do NOT want your plugin .jar file at any location within the main application classpath. The plugin .jar file should be able to be at any URL location outside of any other classpath, even perhaps at another web site.
So, the JVM asks B to find the class in C. But B's loader isn't able to find it because it is not in B's classpath. The trick is to do one of a couple things. First, remember that each loader keeps a list of dependent loaders. Second, in order to avoid any tie-in to the main classpath, we break the normal classloader delegation model by overriding the loadClass() method. In here we want to first check our local cache of loaded classes. The built-in method findLoadedClass() handles this for us. If that doesn't return a Class, then we want to look in our own classpath. In this case, we only want to look for any classes in B's plugin .jar file. C's class of course wont be found here. So the next step is to delegate to our "dependent" list of loaders. Aha, you say? This is the trick (credit goes to the Eclipse IDE team where a few members taught me this and was able to help me solve my very same problem). By delegating to a dependent loader, B's loader effectively asks C's loader to find C's class. The same thing happens, only this time it is now C's loader doing the work. The very first time the calls is made, no classes are loaded yet, so the finding of the C class in the local cache of C's loader wont yet work. The next step though, looking in C's classpath (C's .jar file) WILL find the class. It is loaded, put in C's loader cache and the Class is returned. Now, at this point B now has a Class from C's classpath that it can use.
Now, my first foray into this made me think that if B asks C to find it, and C finds it and loads the bytecode, doesn't B's loader also need the bytecode in order to properly "see" the C class. Apparently, this is not needed. I am guessing the JVM keeps a repository of bytecode, so that so long as you have the C ref (location in the JVM's memory where C's bytecode is), you don't need to re-load the bytecode of C into B's loader. Thus, B's loader now can "see" the C class without actually having to have loaded the bytecode of C. Now, B's code can typecast C, use it, etc. Beautiful aint it?
Let me know if you have any further questions.

Loading classes from another jar file

I've set up my jnpl file so that it references a core jar file (contains main() function). The jnlp also references another jar file (app.jar) which contains class files that I load and instantiate dynamically (using ClassLoader). The core.jar file contains a manifest that includes a reference to app.jar.
The app works fine when I use "java -jar core.jar" from the command line.
However, when I wrap the jars using jnlp, I always get a null pointer exception because it cannot find any class that is in the app.jar file. I've tried different strategies, such as trying to load a class file that sits on the server (in a jar file and not in a jar file), but that also fails if I use jnlp (However, it works if I use "java -jar core.jar")
Any ideas what is going on?

This is the "OckCore.jar" manifest before signing:
Manifest-Version: 1.0
Main-Class: com.Ock.OckCore.OckApp
Class-Path: . OckMaths.jar
Created-By: 1.4.0-beta3 (Sun Microsystems Inc.)
Name: com.Ock.OckCore.OckApp.class
Java-Bean: FalseThis is the manifest after signing:
Manifest-Version: 1.0
Main-Class: com.Ock.OckCore.OckApp
Created-By: 1.4.0-beta3 (Sun Microsystems Inc.)
Class-Path: http://hazel/Ock/. http://hazel/Ock/OckMaths.jar
Name: com/Ock/OckCore/OckApp.class
SHA1-Digest: KRZmOryizx9o2L61nN+DbUYCgwo=I have removed a load of irrelevant stuff from the "after" manifest to keep it readable.
note that :-
The OckApp.class loads normally from webstart and tries to load a class from OckMaths.jar.
I can prove that OckApp.class does load because it creates a log file when it does.
The OckApp.class tries to load a class from the OckMaths.jar. This fails if webstart is used but works if OckCore is launched using "java -jar OckCore.jar".
The jars do exist at the location specified by the manifest.
The application launches normally if I use "java -Jar OckCore.jar"
Here is the jnlp file
<?xml version='1.0' encoding='UTF-8'?>
<jnlp
     spec="1.0"
     codebase="http://hazel/Ock"
     href="OckMaths.jnlp">
     <information>
          <title>Ock Maths Demo</title>
          <vendor>Rodentware Inc</vendor>
          <description>Demo of a ported app running as a Java Webstart application</description>
          <description kind="short">An app running as a Java Webstart application"></description>
          <offline-allowed/>
     </information>
     <security>
          <all-permissions/>
     </security>
     <resources>
          <j2se version="1.3"/>
          <jar href="OckCore.jar"/>
          <jar href="OckMaths.jar"/>
     </resources>
     <application-desc main-class="com.Ock.OckCore.OckApp">
</jnlp> I have also signed the jars outside of a webdirectory. I get the following manifest file:
Manifest-Version: 1.0
Main-Class: com.Ock.OckCore.OckApp
Created-By: 1.4.0-beta3 (Sun Microsystems Inc.)
Class-Path: . OckMaths.jar
Name: com/Ock/OckCore/OckApp.class
SHA1-Digest: KRZmOryizx9o2L61nN+DbUYCgwo=
note that :-
The jars do exist at the location specified by the manifest.
The application launches normally if I use "java -Jar OckCore.jar".
The application doesn't launch from webstart.
I've found that cache, but the jar files have been renamed.
OckCore.jar is anOckCore.jar, etc... so I'm not sure if trying to write a cmdline will work anyway.

Use classes from a jar archive from in a jar archive

Hi, I am making a program and I need some the classes in a certain jar archive for tehm to work. Well my program workes before I add it to a jar be when I make it into one and put the needed jar in it, the program breaks. So does anyone know how to access the class of the jar in my jar?

Well my program workes before I add it to a jar be when I make it into one and put the needed jar in it, the program breaksIt might be easier not to nest the jar files. Instead make the "needed" jar part of the class path when you make your jar file's manifest.
[http://java.sun.com/docs/books/tutorial/deployment/jar/downman.html]

Unable to load classes from jar files inside APP-INF/lib in EAR.

Weblogic version: 10.3.3
Platform: Linux x86-64 bit
We deployed an ear packaged with all the common library jars inside APP-INF/lib. Deployment was successful.
for some reason, it is always giving ClassNotFoundException for the classes inside the jars. This does not happen
in 10.3.2 version of weblogic.
We tried to add them to domain/lib directory (instead of APP-INF/lib) but still it is not able to resolve the classes.
Any pointers would be appreciated.

try using prefer-web-inf-classes in the weblogic.xml file in your WAR file
or using prefer-application-packages in the weblogic-application.xml file in your EAR.

Applet inside a JAR: Cannot access other classes within the JAR

Hello,
Description
Web app + applet (packaged in a JAR)
I have followed this tutorial
JAR contents
package mypackage
SimpleApplet.class
SimpleObj.class
_"SimpleApplet" uses "SimpleObj"_
package mypackage;
public class SimpleApplet extends JApplet {
    @Override
    public void init() {
        SimpleObj obj = new SimpleObj();
HTML code
<applet archive="SimpleApplet.jar" codebase="." code="mypackage.SimpleApplet.class" width="800" height="600" />
SimpleObj cannot be found (Java Console)
java.lang.NoClassDefFoundError: mypackage/SimpleObj
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: mypackage.SimpleObj
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
... 8 more
Caused by: java.io.IOException: open HTTP connection failed:*http://localhost:8080/SimpleApp/mypackage/SimpleObj.class*
at sun.plugin2.applet.Applet2ClassLoader.getBytes(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader.access$000(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
... 12 more
Exception: java.lang.NoClassDefFoundError: mypackage/SimpleObj
It looks like JRE does not search for the SimpleObj class inside the JAR, but tries to get it from the server...
Any ideas?
Thanks in advance,
Gerard
Edited by: gsoldevila on Dec 10, 2008 2:05 AM

misread, deleted
Edited by: atmguy on Dec 10, 2008 1:12 PM

Problems with JApplet, jar-Archive, packages and IE5

Hello!
I have a problem with a JApplet and Internet Explorer 5. I made a jar archive of my classes. The classes are
members of a package. The jar archive also contains images.
The structure of the archive:
com/mycomp/myapp/DemoApplication.class
com/mycomp/myapp/DemoApplet.class
<more classes>
com/mycomp/myapp/images/hp_logo.gif
com/mycomp/myapp/images/test.gif
<more images>
The archive is stored locally in a directory which contains also the html file.
I used the sdk 1.3.1 to compile the classes.
My problem: when I start the html file on NT with IE5, I get the error message below:
I try to create a label containing an icon with:
topLabel.setIcon(new javax.swing.ImageIcon(getClass().getResource("images"+fs+"hp_logo.gif")));It works on Sun with Netscape 4.67 and SDK 1.3.1 installed.
Should I move the images directory inside the jar archive to another place or is the html code not correct?
The error message:
java.lang.NullPointerException
     at javax.swing.ImageIcon.<init>(Unknown Source)
     at com.mycomp.myapp.DemoApplication.initComponents(DemoApplication.java:158)
     at com.mycomp.myapp.DemoApplication.<init>(DemoApplication.java:55)
     at com.mycomp.myapp.DemoApplet.<init>(DemoApplet.java:24)
     at java.lang.Class.newInstance0(Native Method)
     at java.lang.Class.newInstance(Unknown Source)
     at sun.applet.AppletPanel.createApplet(Unknown Source)
     at sun.plugin.AppletViewer.createApplet(Unknown Source)
     at sun.applet.AppletPanel.runLoader(Unknown Source)
     at sun.applet.AppletPanel.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)The html file:
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html>
<head>
    <title>DemoApplet</title>
</head>
<body>
<BODY LINK="#0000ff" VLINK="#800080" BGCOLOR="#37a1a7">
      <h1>DemoApplet</h1>
      

<SCRIPT LANGUAGE="JavaScript"></SCRIPT>
<COMMENT><SCRIPT LANGUAGE="JavaScript1.1"></SCRIPT></COMMENT>
<SCRIPT LANGUAGE="JavaScript"></SCRIPT>
<APPLET CODE = com.mycomp.myapp.DemoApplet CODEBASE = "." ARCHIVE = "DemoApplet.jar,classes12.zip" WIDTH = 695 HEIGHT = 525></XMP>
<PARAM NAME = CODE VALUE = com.mycomp.myapp.DemoApplet >
<PARAM NAME = CODEBASE VALUE = "." >
<PARAM NAME = ARCHIVE VALUE = "DemoApplet.jar,classes12.zip" >
<PARAM NAME="type" VALUE="application/x-java-applet;jpi-version=1.3.1">
<PARAM NAME="scriptable" VALUE="false">
</APPLET>
</NOEMBED></EMBED></OBJECT>


</body>
</html>Thank you for your help!
Gruesse,
Torsten

seems like it couldn't find the image file... try to give it the absolute path to the file first to see if this is the root of the problem... and then try to find alternative ways to not give it the absolute path...

Need help including classes from a jar in compiler

I feel pretty stupid...I've been attempting to incorporate classes inside a jar file for 2 hours now and I can't figure out what I'm doing wrong.
I am using JBuilder. I believe my best attempt was to "Add Files/Packages/Classes" to the project and selecting the .jar file. I have tried this with the file residing in the project folder and in the class folder. Neither has worked.
When I try to create a new instance of a compiled class file residing in the jar file, the compiler doesn't recognize the class name.
I have tried to import it using various strings, but none have been successful.
Can anyone please tell me what I should be doing?
Thanks.
( In case it is at all relevant the class I am trying to import is a LookAndFeel. I am trying to call it, as the instructions say, using the line UIManager.setLookAndFeel(new LookAndFeelName()); The only other thing the instructions say is to "add the .jar file to your classpath." )

Thanks.
I tried that, but no change! I still get the error:
"cannot find symbol; symbol : class LookAndFeelName"
Here's exactly what I did. I clicked on the Required Libraries tab, clicked on Add.
There is a Library tab and an Archives tab at the top of the new Window. In the Library tab, I clicked new..it wants me to specify a folder, so I specify the .jar. This doesn't work. I also went to the Archives tab, and specified the jar from there.
Neither works. What am I doing wrong?

URLClassLoader - loading classes inside of JAR archives

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