tomcat 7 encounters LifecycleException caused by java.lang.UnsupportedClassVersionError

i'm using apache tomcat 7 with jdk 1.7. i have so far been unsuccessful with running even one servlet.

i created my web application hierarchy as:

or
web application hierarchy

the java code is:

// To save as "<TOMCAT_HOME>\webapps\hello\WEB-INF\classes\HelloServlet.java"
package com.training;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
 
public class HelloServlet extends HttpServlet {
 @Override
 public void doGet(HttpServletRequest request, HttpServletResponse response)
 throws IOException, ServletException {
 
 // Set the response MIME type of the response message
 response.setContentType("text/html");
 // Allocate a output writer to write the response message into the network socket
 PrintWriter out = response.getWriter();
 
 // Write the response message, in an HTML page
 try {
 out.println("<html>");
 out.println("<head><title>Hello, World</title></head>");
 out.println("<body>");
 out.println("<h1>Hello, world!</h1>"); // says Hello
 // Echo client's request information
 out.println("Request URI: " + request.getRequestURI() + "");
 out.println("Protocol: " + request.getProtocol() + "");
 out.println("PathInfo: " + request.getPathInfo() + "");
 out.println("Remote Address: " + request.getRemoteAddr() + "");
 // Generate a random number upon each request
 out.println("A Random Number: " + Math.random() + "");
 out.println("</body></html>");
 } finally {
 out.close(); // Always close the output writer
 }
 }
}

and the web.xml code is:

but i always get a 404 error message every time i run: http://localhost:8080/hello/sayhello

i then checked the stderr log and found that

Nov 7, 2011 4:11:42 PM org.apache.catalina.core.ContainerBase addChildInternal
SEVERE: ContainerBase.addChild: start:
org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/hello]]
.
.
.
Caused by: java.lang.UnsupportedClassVersionError: com/training/HelloServlet : Unsupported major.minor version 51.0 (unable to load class com.training.HelloServlet)

any thoughts as to how i may resolve this so that i can run my java servlets?

Try to access it by: http://localhost:8080/myWebApp/sayhello

That's almost always a sign that you compiled the class with a deferent version of Java than Tomcat is using.

Joseph Idol wrote:i'm using apache tomcat 7 with jdk 1.7. i have so far been unsuccessful with running even one servlet.

Caused by: java.lang.UnsupportedClassVersionError: com/training/HelloServlet : Unsupported major.minor version 51.0 (unable to load class com.training.HelloServlet)

That error indicates that the class has been compiled by a Java 7 compiler* but you're using an earlier JRE version. Make sure that Tomcat is really using your Java 7 installation, and not some other version.

* See here.

Bear Bibeault wrote:That's almost always a sign that you compiled the class with a deferent version of Java than Tomcat is using.

THANK YOU!
I was blowing my head out here...