Question

I got “java.lang.NoClassDefFoundError” Exception when I want to use a certain jar file.

Exception in thread "main" java.lang.NoClassDefFoundError: .
org/apache/http/client/ClientProtocolException
    at ?uk.org.taverna.server.client.connection.ConnectionFactory.getConnection(ConnectionFactory.java:63)
    at uk.org.taverna.server.client.Server.<init>(Server.java:99)
    at uk.org.taverna.server.client.Server.<init>(Server.java:126)
    at uk.org.taverna.server.client.Server.connect(Server.java:293)
    at uk.org.taverna.server.usage.ServerUsage.Usage(ServerUsage.java:24)
    at Test.main(Test.java:23)
Caused by: java.lang.ClassNotFoundException: org.apache.http.client.ClientProtocolException
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)

I import this jar file to jar library, when I call the method in that jar file I got this Exception. By the way, This jar file be wrote by myself, and I can run it correctly.
I have no idea how to solve this problem, I am quite new in java.

Thanks in advance.

Sandy

Answer 1

You need also at least HttpClient jar-library. You can get it at Apache Commons web-site.

Jar libraries may and often refer to another jar libraries. In your case library you are using refers to HttpClient library from Apache Commons framework. You need to add this library to your project.