Using Eclipse Mars .I have already added aws java sdk 1.11.123 through install software from help.Now when i run Tomcat Server 7 I get this error:
May 02, 2017         
        
Tomcat has its own file for dependencies. It is possible to configure the build path in Eclipse AND not add the dependencies to Tomcat for the build/deploy which could cause Java to throw that error.
Recreate your project as a dynamic web project in Eclipse (Check the documentation on how to do that if you're not familiar). Then include any 3rd party jars or libs in the auto-generated 'WEB-INF/lib' folder in addition to the build path necessary to run from source in Eclipse (aka the way you're doing it now). Then when you're ready to deploy, export to a war file and all the necessary libs in the 'WEB-INF/lib' folder will be visible to your compiled source.