More than one class in a file, compile one class - all get compiled

If I have 2 classes in a file named Apple.java - classes Apple and Orange. Apple contains main function. I use javac Apple.java - I notice this outputs Apple.class AND Orangle.class.

What are the rules? Is this a convenience to save have to compile each class?

Angus

You're compiling files not classes. Using your example, javac Apple.java compiles Apple.java file not Apple class.

Yes I worked it out in my head shortly after posting.

Just confusion I suppose between javac which takes a file and java which takes a classname.

Got it now.

But then there is more to this. Because if I have this source:

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

And save it to a file called anything.java then if I javac anything.java I get error:
javac anything.java
anything.java:1: class MyFirstClass is public, should be declared in a file name
d MyFirstClass.java
public class MyFirstClass
^
1 error

So is the rule that the file must be named the name of the class containing the main function?

The rule is:
if you've got a public class in a file, then file name must be the same as class name.
if all classes in file are with default access modifier, then name of file is up to you.

I think you mean public class, but for the rest you're right.

Jacek Garlinski wrote: . . .
if you've got a public function in a file, . . . .

You mean public top-level class. I presume.

Campbell Ritchie wrote:

Jacek Garlinski wrote: . . .
if you've got a public function in a file, . . . .

You mean public top-level class. I presume.

Rob Spoor wrote:I think you mean public class, but for the rest you're right.

You all are right ;)