Sunday, December 30, 2007

Java Class finder with a UNIX command

Being a Java developer or Java based Application server administrator like WebSphere or WebLogic , i am sure you should have come across this exception " Error: java.lang.ClassNotFoundException " which basically implies that the JVM is unable to find a definition for your class. It is usually resolved by adding the jar file that contains the class to the classpath or packaging the jar file along with your EAR or WAR file or placing the jar file in the right locations so that your Application Server classloader can find and load the class . So inorder to indentify the .jar file where the class file is present , the following simple UNIX command will help us to indentify the jar file and take appropiate actions to resolve the issue .

LINUX:

find PATH -name '*.jar' -o -name '*.war' -o -name '*.ear' -type f |xargs -i bash -c "jar -tvf {}| tr / . | grep CLASSNAME && echo {}"

(e.g)
find /usr/IBM/WebSphere/AppServer/ -name '*.jar' -o -name '*.war' -o -name '*.ear' -type f | xargs -i bash -c "jar -tvf {}| tr / . | grep org.apache.xerces.dom.DocumentImpl.class && echo {}"


Output:

11160 Fri Feb 20 14:00:34 PST 2004 org.apache.xerces.dom.DocumentImpl.class
/usr/IBM/WebSphere/AppServer/archive_lib/xerces-2.6.2.jar
11160 Fri Oct 06 10:12:24 PDT 2006 org.apache.xerces.dom.DocumentImpl.class
/usr/IBM/WebSphere/AppServer/updateinstaller/update.jar


The above command will recursively search all the jar , EAR and WAR files under the /usr/IBM/WebSphere/AppServer/ for the class name org.apache.xerces.dom.DocumentImpl.class and output the location of the .jar file that contains the class.

Although this command is useful only in unix environment but there are other java based utilities to find the same like Jar Class Finder , Java class finder, etc , but i find this command simple to use without having to copy addtional jar files to your systems.

1 comment:

Anonymous said...

you have a nice site.thanks for sharing this site. various kinds of ebooks are available here

http://feboook.blogspot.com

There was an error in this gadget