Question

I see a code where there are two interfaces having some methods with two methods having same name. Then there is a class that implements these interfaces i think it should not have compiled because of ambiguity in method names. Why does it works fine.

Answer 1

Every language in which this problem can occur will solve the problem differently. In some languages, this can be an error; C++ is this way. But in Java, as long as the two methods have compatible exception specifications — i.e., as long as it’s actually possible to implement a method that satisfies both interfaces — then it’s specifically allowed by the language spec. The one method satisfies each interface, and everything is fine. It’s meaningless to ask which interface the method belongs to; it belongs to both, or to none.

Note that you can have a class with a method x(), and then extend that class with a child class that declares itself to implement some interface that includes a method x(); the child automatically satisfies the interface using the inherited method, which itself was declared with no knowledge whatsoever of the interface. As you can see, Java interfaces are purely declarative; they don’t care where the method comes from, only that the class in question includes them.

I can’t speak for PHP, but perhaps it’s just the same, but I’m sure it differs in some of the small details.