为什么在classpath规范中找不到jar文件？ （来自Oracle的FileChooserDemo）

Question

Downloaded the latest Java SE. Ran FileChooserDemo via JNLP at http://docs.oracle.com/javase/tutorial/uiswing/components/filechooser.html Works fine. (Windows box.)

Downloaded the source from http://docs.oracle.com/javase/tutorial/uiswing/examples/components/index.html#JWSFileChooserDemo

Following the compile instructions in the java source:

C:components> javac -classpath .;jars/jnlp.jar JWSFileChooserDemo.java 

This works fine. Two class files are generated in the components dir. Then...

C:components>cd .. 
C:src> java -classpath .;jars/jnlp.jar components.JWSFileChooserDemo 
Exception in thread "main" java.lang.NoClassDefFoundError:javax/jnlp/UnavailableServiceException 
at java.lang.Class.getDeclaredMethods0(Native Method) 
. 
. 
. 

So the UnavailableServiceException.class isn't being found. But if you list the jar file, the class IS there. So my classpath is just wrong.

C:jars> tar tf jnlp.jar
META-INF/
META-INF/MANIFEST.MF
javax/jnlp/
javax/jnlp/BasicService.class
javax/jnlp/ClipboardService.class
javax/jnlp/DownloadService.class
javax/jnlp/DownloadServiceListener.class
javax/jnlp/ExtensionInstallerService.class
javax/jnlp/FileContents.class
javax/jnlp/FileOpenService.class
javax/jnlp/FileSaveService.class
javax/jnlp/JNLPRandomAccessFile.class
javax/jnlp/PersistenceService.class
javax/jnlp/PrintService.class
javax/jnlp/ServiceManager.class
javax/jnlp/ServiceManagerStub.class
javax/jnlp/UnavailableServiceException.class

I tried this on Mac OSX (you have to change semicolons into colons in the classpath) and same exact thing.

Update: I found an older version of this demo online that doesn't use UnavailableSewrviceException and compiles standalone. It works fine with current Java and suits my purposes. I still do not understand why the commands given above do not work.

Answer 1

Follow these steps :

Say the directory structure is this on my side, under C Drive :

---

  components-JWSFileChooserDemoProject
                  |
  ------------------------------------
  |           |           |          |
nbproject    src      build.xml    manifest.mf
              |
          components
              |
  -------------------------------------------------
  |       |       |                               |
images   jars     |                               |
             JWSFileChooserDemo.java      JWSFileChooserDemo.jnlp

---

Under components Directory create a new Directory called build so now Directory - components will have five thingies, instead of four ie build , images , jars , JWSFileChooserDemo.java and JWSFileChooserDemo.jnlp .

Now first go to components Directory .

To compile write this command :

C:\components-JWSFileChooserDemoProject\src\components>javac -classpath images\*;jars\*;build -d build JWSFileChooserDemo.java

Here inside -classpath option, you are specifying that content of Directories images , jars and build is to be included while compiling JWSFileChooserDemo.java . -d option basically tells, as to where to place the .class files.

Move to "build" folder :

C:\components-JWSFileChooserDemoProject\src\components>cd build

Run the Program :

C:\components-JWSFileChooserDemoProject\src\components\build>java -cp .;..\images\*;..\jars\* components.JWSFileChooserDemo

Here inside -cp option . represents, that look from the current position, ..\\images\\* means, go one level up inside images Directory , from the current location and get all its contents and the same goes for ..\\jars\\* thingy too.

Now you will see it working, and giving the following output :

---

EDIT 1 :

Since you wanted to do it without -d option of the Java Compiler - javac . Considering the same directory structure, as before, move inside your components Directory .

COMPILE with this command :

C:\components-JWSFileChooserDemoProject\src\components>javac -classpath images\*;jars\* JWSFileChooserDemo.java

Now manually create the package structure in the File System , ie create Directory components and then move your .class files created previously, inside this newly created components Directory , and also add images folder to this newly created components folder.

Now Directory - components will have five thingies, instead of four ie components(which further contains JWSFileChooserDemo.class , JWSFileChooserDemo$1.class and images folder) , images , jars , JWSFileChooserDemo.java and JWSFileChooserDemo.jnlp .

RUN the program with this command :

C:\components-JWSFileChooserDemoProject\src\components>java -cp .;jars\* components.JWSFileChooserDemo

This will give you the previous output, though, if you wanted to move as suggested before, again copy images folder to the automatically generated components folder, since I just looked inside the .java and they using relative path for it to work.

---

JUST THIS PARTICULAR SOLUTION, I AM ABOUT TO DESCRIBE WILL WORK FOR YOUR CASE ONLY :

If after javac command given before, if you don't wanted to create any folder, then go one level up, ie outside components directory and use this command to run the program

C:\components-JWSFileChooserDemoProject\src>java -cp .;components\jars\* components.JWSFileChooserDemo

If you don't wanted to