how to implement interface

[makpandian]

i create interface

interface arith
{
int sum(int a,int b);
int sub(int x,int y);
}


when i implenent this interface i only define int sum(int a,int b);

but i got a error that the function sub did not define.but i only access sum function only not sub.....

should we define all declare function in interface?....

[Eranga]

When you implement an interface you must implement all methods in that interface in the implementing class.

Can you show how you implement that interface.