I am looking for some libraries and some examples to create an client OPC application in Java which could connect with opc server. Thanks in advance.
Have you checked out OPC Client Programming with Java?
They offer different links for this area:
Utgard is an open source project offering an OPC library written in pure native Java, i.e. with no dependency on JNI or other DLLs. It is licensed under the GPL.
Antonín Fischer's Java OPC Client is now greatly enhanced and hosted on SourceForge. It uses a JNI layer coded in Delphi. Full source code (both Java and Delphi) is provided.
I think what you are looking for is Utgard, you can find sample code in the documentation sections, respectively in the project source code under documentation.