Hello everyone,

I stumbled upon a java compilation puzzle that I would like to discuss
with you.
Let's say I have two classes Foo and Bar defined as:

public class Foo {
}

public class Bar {
  public Bar(String s) {}
  public Bar(Foo f) {}
}

I can compile Foo first and then I can compile Bar with Foo in javac's
classpath. So far, so good.

Let's say now that I have the following Main class:

public class Main {
  public static String main(String[] args) {
      for (int i = 0; i < args.length; i++) {
          Bar b = new Bar(args[i]);
      }
  }
}

That code does not mention the class Foo yet it will not compile if
Foo is not in the classpath. The error I get is:

src/Main.java:5: cannot access Foo
file Foo.class not found
           Bar b = new Bar(args[i]);
                   ^
1 error

I can understand that javac needs to disambiguate the two constructors
of Bar to compile the Main class. But I do not understand why it needs
to actually have the Foo class for that. It knows String and knows
that it does not implement or extend Foo. So there is no ambiguity in
the call to the String-based constructor: it can't be the
Foo-based one.

I do not bring this issue just for argument's sake. I am in the
situation where I have a jar containing Bar and Foo is in a second jar
that I don't have. My code (Main) would not compile without Foo so I
had to create a fake Foo class just to compile successfully. It seems
kind of silly. Or did I miss something?

Cheers,

Thomas