![Java Interface Example
//Interface declaration: by first user
interface Drawable
{
void draw();
}
//Implementation: by second user
class Rectangle implements Drawable
{
public void draw()
{
System.out.println("drawing
rectangle");
}
}
class Circle implements Drawable
{
public void draw()
{
System.out.println("drawing circle");
}
}
//Using interface: by third user
public class TestInterface1
{
public static void main(String args[])
{
Drawable d=new Circle();//In real
scenario, object is provided by
method e.g. getDrawable()
Drawable r=new Rectangle();
d.draw();
r.draw();
}
}](https://image.slidesharecdn.com/interfaceinjava-190405210634/85/Interface-in-java-multiple-inheritance-in-java-interface-implementation-9-320.jpg)
![Multiple inheritance using interface
interface Printable
{
void print();
}
interface Showable
{
void show();
}
public class A7 implements
Printable,Showable
{
public void print()
{
System.out.println("Hello");
}
public void show()
{
System.out.println("Welcome");
}
public static void main(String
args[])
{
A7 obj = new A7();
obj.print();
obj.show();
}
}](https://image.slidesharecdn.com/interfaceinjava-190405210634/85/Interface-in-java-multiple-inheritance-in-java-interface-implementation-11-320.jpg)
Interface in java ,multiple inheritance in java, interface implementation
- 1. P R E S E N T E D B Y : P R A J J A V A L R A O C H I N T A L Interface in Java
- 2. What is an interface An interface in java is a blueprint of a class. It has static constants and abstract methods. The interface in Java is a mechanism to achieve abstraction. It is used to achieve abstraction and multiple inheritance in Java.
- 3. Why use Java interface? It is used to achieve abstraction. By interface, we can support the functionality of multiple inheritance. It can be used to achieve loose coupling.
- 4. Multiple inheritance is not supported through class in java, but it is possible by an interface, why? multiple inheritance is not supported in the case of class because of ambiguity. However, it is supported in case of an interface because there is no ambiguity. It is because its implementation is provided by the implementation class.
- 5. How to declare an interface? An interface is declared by using the interface keyword. all the methods in an interface are declared with the empty body, and all the fields are public, static and final by default. A class that implements an interface must implement all the methods declared in the interface.
- 6. Syntax: interface <interface_name> { // declare constant fields // declare methods that abstract // by default. }
- 7. Working of compiler The Java compiler adds public and abstract keywords before the interface method. Moreover, it adds public, static and final keywords before data members.
- 8. The relationship between classes and interfaces As shown in the figure given below, a class extends another class, an interface extends another interface, but a class implements an interface.
- 9. Java Interface Example //Interface declaration: by first user interface Drawable { void draw(); } //Implementation: by second user class Rectangle implements Drawable { public void draw() { System.out.println("drawing rectangle"); } } class Circle implements Drawable { public void draw() { System.out.println("drawing circle"); } } //Using interface: by third user public class TestInterface1 { public static void main(String args[]) { Drawable d=new Circle();//In real scenario, object is provided by method e.g. getDrawable() Drawable r=new Rectangle(); d.draw(); r.draw(); } }
- 10. Multiple inheritance in Java by interface If a class implements multiple interfaces, or an interface extends multiple interfaces, it is known as multiple inheritance.
- 11. Multiple inheritance using interface interface Printable { void print(); } interface Showable { void show(); } public class A7 implements Printable,Showable { public void print() { System.out.println("Hello"); } public void show() { System.out.println("Welcome"); } public static void main(String args[]) { A7 obj = new A7(); obj.print(); obj.show(); } }