How Can You Create Your Own Interface?

Definitely we can create our own interface :

syntax
interface interfacename
{
      method definitons only
}

We can't create instances for interfaces we can implement them in any class. Java does not support multiple interface this can be achieve by using interfaces
A class can extends only one class but we can implemnet any numberof interfaces but we define all the menthod in an interface in a class the implement the interface