Why Dot class file name and name of the class should be same?

  
   ANS : When JVM searches for class it will look at the file name of the Dot class file , it will not look in to the byte code of the Dot class file . 

      So if  we are searching for a particular class let us say "House" class in a particular JAR file ,  there is a House class in that  JAR File but the file name[byte code file] of that  House class is Apple then ,JVM cannot able to figure out House class , so inorder to avoid that confusion Dot class file name and class name should be same.

See the below image to understand how it works....

[Any Doubt please  , Feel free to ask i will try my level best to clear your doubt]