Am not able to run the java program - pls help

Question

1. I installed java in the below path
     c:\program files\java\jdk1.5.0
     c:\program files\java\jre1.5.0
I set the path in
     User variable i. variable name: path
          ii. variable value: c:\program files\java\jdk1.5.0\bin
when I compile it in command prompt-applying javac ? it performed successfully-shows
options like ?g create all debug info, -g : new Generate no debug info etc.,
But am not able to run the file. It shows error msg.
2. I specified the same name for file name & class name.
3. Java <class name>
     Exception in thread ?main?java.lang.NoclassDeffoundError: <class name>
4. Java ?cp <class name>
     Unrecognized option: -cp.<classname>
     Could not create the Java Virtual Machine
5. Java ?classpath . <classname>
     Exception in thread ?main?.java.lang.unsupported classversionError: <classname>
     <unsupported major.minor version 49.0
          at java.lang.classloader.defineclass0<native method>
          at java.lang.classloader.defineclass<unknown source>
               --and many listed below?
6. Java ?classpath c:\program files\java\jdk1.5.0\bin <class name>
     Exception in thread ?main?java.lang.NoclassDeffoundError: <class name>
7. I re-installed the java, but still the problem continuing.
pls help... its very urgent

Answer 1

Is the java class you compiled/calling in the default package? If it is not, you will have to call it by the fully qualified name.
e.g.
package com.mycompany.myproject;
public class MyClass {
    public static void main(String[] args) { }
}This would be called as "Java com.mycompany.myproject.MyClass" and must contain a main method with signature as above.
You would have to call this from folder where the compiled classes are located. If using package, you would call from directory at level of top most package so com folder in this example as Java will look at each package name in qualified name and try to traverse directories with those same names to get to .class file matching class name specified. To avoid this, your newly compiled .class files must also be in your classpath.
Hopefully that helps.
--Kevin