Eclipse normally uses a JRE (Java
Runtime Environment), and not a full JDK, but Tomcat must have access to a JDK.
You should, therefore, first define a JDK for Tomcat. First select
Window/Preferences/Java/Installed JREs:

As you can see only a JRE is available. Press the "Add..." button to
add a JDK to the list:

Pres the "OK" button and then check the new JDK:

This JDK must also be selected in Window/Preferences/Tomcat/JVM
settings:

You complete the plug-in setup by entering the userid/password for the Tomcat
Admin program:

The two main features of the Tomcat plug-in
What you have achieved now is first of all two things:
- A new type of Java project, called a Tomcat project
- A way of starting and stopping Tomcat from within Eclipse.
New on the Java Boutique:
New Review:
Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling
API boasts simplicity, ease-of-integration, a well-rounded feature
set, and it's free!
New Applet:
Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA
sequences into three useful formats.
Elsewhere on internet.com:
WebDeveloper Java
Lots of Java information on webdeveloper.com
WDVL Java
Thorough Java resource at the Web Developer's Virtual Library.
ScriptSearch Java
Hundreds of free Java code files to download.
jGuru: Your View of the Java Universe
Customizable portal with online training, FAQs, regular news updates, and tutorials.