找不到主类：即使Manifest指定了该类，Java也会出错

Question

This is a very popular error and since I am new to Java I may be misunderstanding other people's answers:

On Windows 7 with JRE 1.6

I copied the First Steps package from Restlet to try on my own as a Stand alone app. I have a class called FirstStepsMain (see Class below) and define it in my Manifest (see Manifest below) as "Main-Class: firstSteps.FirstStepsMain". I set my class path variable in Windows to \\firstSteps.jar. Thinking that it might be that the external jars were not being seen I moved them to the same folder and set Windows class paths for them too.

I have even used the -classpath command with just the first Jar and all three Jars:

E:\ResultsDashboard>java -verbose -classpath e:\ResultsDashboard\firstSteps.jar;e:\resultsdashboard\org.restlet.jar;E:\ResultsDashboardorg.restlet.ext.servlet.jar -jar firstSteps.jar

And yet I still get the error. Any help would be appreciated.

Class :

package firstSteps;

import org.restlet.Component;
import org.restlet.data.Protocol;

public class FirstStepsMain {

public static void main(String[] args) throws Exception {  
    // Create a new Component.  
    Component component = new Component();  

    // Add a new HTTP server listening on port 8182.  
    component.getServers().add(Protocol.HTTP, 8182);  

    // Attach the sample application.  
    component.getDefaultHost().attach("/firstSteps",  
            new FirstStepsApplication());     
    // Start the component.  
    component.start();  
}
}

Manifest :

Manifest-Version: 1.0
Main-Class: firstSteps.FirstStepsMain

Class-Path: firstSteps.jar [note: I added this as a desperate attempt]

Answer 1

You need to put Main-Class: firstSteps.FirstStepsMain in second line of the manifest file.
Please see Understanding the Manifest

Answer 2

When you start a Java program with the -jar option, the -classpath option on the command line will be ignored. So it doesn't matter what you specify there.

Instead, you must specify the classpath in the manifest file. Add all the JARs that the program needs to the Class-Path attribute in the manifest file, but not firstSteps.jar itself. It should look for example like this:

Class-Path: org.restlet.jar org.restlet.ext.servlet.jar

See Adding Classes to the JAR File's Classpath from the tutorial Packaging Programs in JAR Files .

You should then be able to run it with:

java -jar firstSteps.jar