sometimes I start my java program with
public class program_name{
and sometimes I start with
class program_name{
my program runs with public class & class, what is the difference or role of public at start?

Question

sometimes I start my java program with 
public class program_name{
and sometimes I start with 
class program_name{
my program runs with public class & class, what is the difference or role of public at start?

anonymous · Answer

The difference is whether or not other classes will be able to access the contents of the class you've made. Remember, when you write a java program, you don't have to put all the classes in one file, they can all have their own file, as long as they are in the same directory. I think what you're really getting onto is a concept in java & other languages called "access modifiers." This should provide you with the right information: http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html

konradzuse · Answer

If you have a class named "pie" for example you will need to do public class pie.  Under that yu could have class lasagna, etc.

anonymous · Answer

public, private, static, global, dynamic, OOP all good keywords