What is the use of interface as the same methods are defined on another class and only the declaration happens in interface?

Question

I think it is not needed since we can declare a method directly without using interface. If any other hidden concepts of interface are available please clarify me.

Answer 1

Because you can do
IExample foo = new ExampleImpl1();
foo = new ExampleImpl2();

Answer 2

Sure it has. For example, you could do IConnection or something like that.

Answer 3

You can define IConnection as an interface for different kinds of internet connections.

Answer 4

please read my question clearly

Answer 5

i think this may not have required advantages

Answer 6

Iconnection means???