Java - The difference between class "ClassName" and public class "ClassName"

Question

What's the difference between

class x {     //code here } 

and

public class x {     //code here } 

Sometimes I see examples on the Internet and they'll have public class instead of class and they're all simple programs. I use class for my assignments and so does everybody else

Answer 1

The first one will result in your class being assigned the default visibility, that is package-private (ie: accessible within the same package).

The second one makes it public, that is, visible to any other class.

Reference: Controlling Access to Members of a Class

Answer 2

The simplest way to put it:

if everything you have is in the same package (package com.myschool.myapp at the top of every file) then there is no difference, but if anything wants to access anything outside it's package then it must be public.

For instance, "String" is in "java.lang", your package almost certainly isn't in java.lang so if string wasn't public you couldn't access it.