Java running program at command prompt: main class not found or loaded

I'm trying to learn how to compile and run using only the command line in windows This is the directory tree from the root:

D:
 ActivityOne
     - classes
         - com
           -wat
             -sampleapp
                -students
                    StudentE.class
                 StudentMasterList.class (Main)
     - src
         -com
           -wat
             -sampleapp
                -students
                    StudentE.java
                 StudentMasterList.java (Main)

The problem is that I'm confused about how to run the program now I tried two things, both of which returned different errors

First attempt:

java -classpath classes StudentMasterList

Back:

Error: Could not find or load main class StudentMasterList

Second attempt:

java -classpath classes/com/wat/sampleapp StudentMasterList

Back:

Exception in thread "main" java.lang.NoClassDefFoundError: StudentMasterList (wrongname: com/wat/sam
pleapp/StudentMasterList)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(UnkNown Source)
at java.security.SecureClassLoader.defineClass(UnkNown Source)
at java.net.urlclassloader.defineClass(UnkNown Source)
at java.net.urlclassloader.access$100(UnkNown Source)
at java.net.urlclassloader$1.run(UnkNown Source)
at java.net.urlclassloader$1.run(UnkNown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.urlclassloader.findClass(UnkNown Source)
    at java.lang.ClassLoader.loadClass(UnkNown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(UnkNown Source)
    at java.lang.ClassLoader.loadClass(UnkNown Source)
    at sun.launcher.LauncherHelper.checkAndLoadMain(UnkNown Source)

I'm confused after the next attempt. Any help on how to run the main class?

Update: I should run all commands at the activityone level

Solution

The correct way is

java -classpath D:\ActivityOne\classes com.wat.sampleapp.StudentMasterList

In other words, you add the top - level directory to the classpath and use the fully qualified name of the Java class