Question

I have a Java interface in an API that contains a single method:

public interface MyInterface
{
    public void foo();
}

If I add a method to that interface like this:

public interface MyInterface
{
    public void foo();
    public void bar();
}

Do clients using the API need to recompile or can they use the new JAR as is because I didn’t change the signature or an existing method or remove a method?

Answer 1

Short answer: The can use the new API without recompiling.

Here’s a LINK that might help you understand how Java runs bytecode and how it does dynamic linking.