Java XStream Cannot Be Resolved On Ubuntu

I have got the XStream package by apt-get install libxstream-java. I'd like to use the XStream class in my java program, so I try to include the XStream class by importing com.thoughtworks.xst开发者_StackOverflow社区ream.XStream. But it does not work for me complaining the package com.thoughtworks.xstream does not exist. I have found out that the package is installed under directory: usr/share/java. Could someone please explain to me what is happening?

You should add the Xstream.jar to your classpath. See Setting the classpath for more details.