Answers for "what is difference between declaring class as just class and public class in java"

difference between class and object in java

Class is a blueprint or template which
you can create as many objects 
as you like. Object is a member or
instance of a class.
Class is declared using class keyword,
Object is created through new keyword
mainly. A class is a template for objects.
  A class defines object properties
 including a valid range of values, and
 a default value.
 A class also describes object behavior.
   An object is a member or 
 an "instance" of a class and has states
   and behaviors in which all of its
properties have values that you either
   explicitly define or that are defined 
   by default settings.