CODE EXAMPLE FOR JAVA

could not find or load main class org.apache.catalina.startup.bootstrap caused by: java.lang.classnotfoundexception: org.apache.catalina.startup.bootstrap

It seems the server does not have access to two Jar files.

Go to Servers Tab > Double Click on your Server > Open Launch Configuration 
> Classpath(tab) > Click on User Entries > Add External Jars > Add Boorstrap.jar
and tomcat-juli.jar > Apply > Ok
Start the server now.