Are undeclared classes in Java public?

Question

I'm starting to learn java and have created my first hello world function in Eclipse. I've noticed that the following two functions, both in the default package of the src folder in my java project, seem to do the same thing:

class HelloWorld {
    public static void main(String[] args){
        System.out.println("Hello World!");
    }
}

and

public class HelloWorld {
    public static void main(String[] args){
        System.out.println("Hello World!");
    }
}

Both successfully print 'Hello World!' to the console.

I've read a bit about different class types, but am unsure what type of class I would be declaring with the first function. What's the difference between these two functions? Does java make my hello world class in the first case public?

4

they're package-private – soulcheck Apr 24 '13 at 15:37

score 10 · Accepted Answer · edited May 23 '17 at 12:09

Class that is not declaring itself as public is package protected, meaning that the class it is only accessible in that package.

Very useful summary of acccess modifiers on stackoverflow. More at oracle

Example:

So let's say you have the following package structure:

com
  stackoverflow
    pkg1
      public Class1
      Class2
    pkg2
      OtherClass

Class2 can only be used by Class1, but not by OtherClass

score 1 · Answer 2 · answered Apr 24 '13 at 15:38

It's all about class visibility!

A class may be declared with the modifier public, in which case that class is visible to all classes everywhere. If a class has no modifier (the default, also known as package-private), it is visible only within its own package

http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html

score 1 · Answer 3 · answered Apr 24 '13 at 15:39

This took me about 2 seconds to find on Google:

http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html

In answer to your question, the default modifier is package protected, meaning it can only be accessed within the package, but next time please do some research before posting a question, as it took you more time to write the question that it would have to search

score 0 · Answer 4 · answered Apr 24 '13 at 15:39

0

It is protected class ,you cannot access that class out side the package.

If you not specify anything its by default protected

answered Apr 24 '13 at 15:39

Suresh Atta

120,458
37
198
307

Are undeclared classes in Java public?

4 Answers4