Introduction to Programming

Interface types

A variable of an interface type is declared using the corresponding interface name:

<Interface name> variableName;

It can be initialized by assigning to it null or an object (an instance) of the class that implemented the interface. Here is an example:

interface SomeInterface{  void someMethod();}interface SomeOtherInterface{  void someOtherMethod();}class SomeClass implements SomeInterface {  void someMethod(){    ...  }} class SomeOtherClass implements SomeOtherInterface{  void someOtherMethod(){    ...  }}SomeInterface someInterface = new SomeClass();someInterface = new SomeOtherClass(); //not possible, errorsomeInterface.someMethod();         //works just finesomeInterface.someOtherMethod();   //not possible, error

We will talk more about assigning ...