//Difference between extends & implements:-

/*

* (i) one class can extends only one class at a time

* however a class can implement more than one interface at a time.

*

* Note:- one class can extends only one class at a time but one interface can extends multiple interfaces at a time.

*/

interface X

{

void m1();

}

interface Y

{

void m2();

}

class Test implements X,Y

{

public void m1() {}

public void m2() {}

}

/*

* (ii) A class can extends a class and can implements any number of

* interfaces simultaneously.

* But you must follow a sequence of writing-

*

* (a) extends then (b) implements

*/

interface XX

{

void m1();

}

interface YY

{

void m2();

}

class XY

{

void m3()

{

System.out.println("m3 of class XY...");

}

}

class XXY extends XY implements XX,YY

{

public void m1() {}

public void m2() {}

}

/*

* (iii) Legal relation between classes and interfaces-

*

* (a) class & class--> extends (eg: class X extends class Y)

* (b) class & interface--> implements (eg: class X implements interface Y)

* (c) class & class & interface--> extends implements (eg: class X extends Y implements Z)

* (d) interface & interface--> extends (eg: interface X extends interface Y or interface X extends interfaces Y,Z,A)

*

* only these 4 relations are legal any others are illegal

*/

public class FourthCode {

}