Thread: Using 3rd Party JAR Files

I have been working through a java textbook. I have a reasonable grasp of the basic concepts of java programming but one area I am always struggling with is getting the system to recognise 3rd party jar files. I just never seem to be able to get them to work.

I set up the classpath and add them to the directory in the classpath but I always get compiler errors or run time errors not finidng the class. For example, in order to make the apache xml-RPC jar files work I read that all I had to do was add xmlrpc-2.0.jar and xmlrpc-2.0-applet.jar to the classpath. I set the classpath to c:\program files\java\jdk1.6.0_13\lib\ext and put theses files in there, I then tried to compile a piece of example code out of the textbook which worked. However, when I ran the program I got:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/codec/DecoderException
at org.apache.xmlrpc.XmlRpc.createTypeFactory(XmlRpc. java:238)
at org.apache.xmlrpc.XmlRpc.<init>(XmlRpc.java:193)
at org.apache.xmlrpc.XmlRpcClientResponseProcessor.<i nit>(XmlRpcClientResponseProcessor.java:48
at org.apache.xmlrpc.XmlRpcClientWorker.<init>(XmlRpc ClientWorker.java:43)
at org.apache.xmlrpc.XmlRpcClient.getWorker(XmlRpcCli ent.java:347)
at org.apache.xmlrpc.XmlRpcClient.execute(XmlRpcClien t.java:190)
at org.apache.xmlrpc.XmlRpcClient.execute(XmlRpcClien t.java:184)
at org.apache.xmlrpc.XmlRpcClient.execute(XmlRpcClien t.java:177)
at SiteClient.getRandomSite(SiteClient.java:27)
at SiteClient.main(SiteClient.java:14)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.codec.DecoderException
at java.net.URLClassLoader$1.run(URLClassLoader.java: 200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:188)
at sun.misc.Launcher$ExtClassLoader.findClass(Launche r.java:229)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 07)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 52)
at java.lang.ClassLoader.loadClassInternal(ClassLoade r.java:320)
... 10 more

The program itself connects to the author of the books test server and calls a remote procedure called getRandomSite() which returns 3 string variables - url, title and description and outputs them to the console.
The code from the application is below, it is taken from SAMS Teach Yourself Java in 21 Days:

import java.io.*;
import java.util.*;
import java.net.*;
import org.apache.xmlrpc.*;
 
public class SiteClient{
	String url;
	String title;
	String description;
	public static void main(String[] args){
			SiteClient sClient = new SiteClient();
			try {
					Vector response = new Vector();
					response = sClient.getRandomSite();
					if (response.size() > 0) {
							sClient.url = response.get(1).toString();
							sClient.title = response.get(2).toString();
							sClient.description = response.get(3).toString();
							System.out.print("Url: " + sClient.url + "\nTitle: " + sClient.title + "\nDescription: " + sClient.description);
						} 
				}	      catch (IOException ioe) { System.out.print("IO Exception: " + ioe.getMessage()); }
						  catch (XmlRpcException xrpc) { System.out.print("XML Remote Procedure Call Error: " + xrpc.getMessage()); }
			}
	public Vector getRandomSite() throws IOException, XmlRpcException{
			Vector params = new Vector();
			XmlRpcClient client = new XmlRpcClient("http://cadenhead.org:4413");
			Vector result = (Vector) client.execute("dmoz.getRandomSite", params);
			return result;
		}	
}

Can anyone tell me what I'm doing wrong, I've had this problem with most 3rd party jars but was able to get the XOM API working, I haven't done anything differently here.

Thanks for the welcome JavaPF and the help. I will give this a try and post back how I get on. At the minute I'm not using a development environment just text editor + jdk.

I've downloaded, installed Eclipse and have had a go importing third party java applications. It was showing my system library in jdk\jre\lib\ext. I moved all of the relevant jar files into this directory, they show up in the tree but I am still getting the same message when I go to run the app.

Hi thanks for your help again.

It's the same problem I'm afraid. It imports the contents of the jar files. When I expand the jar files in the tree they have all of the classes that I am importing into my program, I go to run > run as > java application and it outputs the same error.

That's the main website below, the textbook told me to download xmlrpc-2.0.jar and xmlrpc-2.0-applet.jar which weren't even in the download on the apache site so I located them through find jar website. I have added all of the files downloaded to the build path now and still the same problem. Thank you for all the help by the way.

ws-xmlrpc - Downloads

JAR Search Engine - findJAR.com

You mean a missing class that should be in the jars or a missing jar altogether? Glad to know I'm not doing anything wrong in particular.

OK found the jar file in question it was commons-codec.jar, imported it into my classpath and the app now runs with a connection timeout IO exception which is probably down to the server not being available at the minute. Thank you for your help I will definately be back here in future.