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| Interface
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Interface is nothing but " Communicating
the Entity (or) Interface is a device or system that unrelated entities use to interact" .
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As you've already learned, objects define their interaction with the outside world through the methods that they expose.
Methods form the object's interface with the outside world; the buttons on the front of your television set, for example,
are the interface between you and the electrical wiring on the other side of its plastic casing. You press the "power"
button to turn the television on and off.
In its most common form, an interface is a group of related methods with empty bodies. A bicycle's behavior,
if specified as an interface, might appear as follows:
interface Bicycle {
void changeCadence(int newValue); // wheel revolutions per minute
void changeGear(int newValue);
void speedUp(int increment);
void applyBrakes(int decrement);
}
To implement this interface, the name of your class would change (to a particular brand of bicycle, for example,
such as ACMEBicycle), and you'd use the implements keyword in the class declaration:
class ACMEBicycle implements Bicycle {
// remainder of this class implemented as before
}
Implementing an interface allows a class to become more formal about the behavior it promises to provide.
Interfaces form a contract between the class and the outside world, and this contract is enforced at build
time by the compiler. If your class claims to implement an interface, all methods defined by that interface
must appear in its source code before the class will successfully compile.
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Example:
public class Main {
public static void main(String[] args) {
shape circleshape=new circle();
circleshape.Draw();
}
}
interface shape
{
public String baseclass="shape";
public void Draw();
}
class circle implements shape
{
public void Draw() {
System.out.println("Drawing Circle here");
}
}
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