Interface
•
Interface looks like a class but it is not a
class.
•
An interface can have methods and variables
just like the class but the methods declared in the interface are by default
abstract (only declaration, nobody)
•
Also, the variables declared in an interface
are constants
Syntax
for defining an interface
interface MyInterface
{
datatype variable=constant;
public void method1();
public void method2();
}
To
implement an interface
class classname implements
interfacename
{
body
of class
}
Example 01:
package Interface;
interface Animal {
void Sound();
void sleep();
}
Class Dog implements Animal
{
@Override
public void Sound() {
System.out.println("The Dog Sounds like : woof");
}
@Override
public void sleep() {
System.out.println("Dog Sleeping");
}
}
public class interfaceDemo{
public static void main(String args[]) {
Dog o =new Dog();
o.Sound();
o.sleep();
}
}
/*Interface looks like a class but it is not a class. An interface can
have methods and variables
just like the class but the methods declared in the interface are by
default abstract
(only method signatures, nobody, see: Java abstract method).
As mentioned above they are used for full abstraction. Since methods in
interfaces do not have body,
they have to be implemented by the class before you can access them.
The class that implements the interface must implement all the methods of
that interface.
Also, the Java programming language does not allow you to extend more
than one class,
however, you can implement more than one interface in your class.*/
Example 02:
package Interface;
//How Multiple inheritance can be achieved by implementing multiple interfaces
class Phone
{
void voiceCall()
{
System.out.println("Make VoiceClass");
}
void sms()
{
System.out.println("We Can send SMS");
}
}
interface Camera
{
void click();
void record();
}
interface player
{
void play();
void pause();
void stop();
}
class SmartPhone extends Phone implements Camera,player
{
@Override
public void click() {
System.out.println("Take a Selfi");
}
@Override
public void record() {
System.out.println("Take a video"); }
@Override
public void play() {
System.out.println("Play Music");
}
@Override
public void pause() {
System.out.println("Pause Music");
}
@Override
public void stop() {
System.out.println("Stop Music");
}
}
public class interfaceDemo2 {
public static void main(String[] args) {
SmartPhone o =new SmartPhone();
o.voiceCall();
o.sms();
o.click();
o.record();
o.play();
o.pause();
o.stop();
}
}
Example 03:
interface circle
{
double
pi=3.14;
double
radius=5.5;
void
compute();
}
class area implements circle
{
public
void compute()
{
double
result;
result=pi*radius*radius;
System.out.println(“Area
of Circle=”+result);
}
}
class circumference implements circle
{
public
void compute()
{
double
result;
result=2*pi*radius
;
System.out.println(“Circumference
of Circle=”+result);
}
}
class interfacedemo
{
public
static void main(String args[])
{
area
a=new area();
a.compute();
circumference
c=new circumference();
c.compute();
}
}
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