CODE EXAMPLE FOR JAVA

Interfaces in Java

// Java program to demonstrate the 
// real-world example of Interfaces
  
import java.io.*;
  
interface Vehicle {
      
    // all are the abstract methods.
    void changeGear(int a);
    void speedUp(int a);
    void applyBrakes(int a);
}
  
class Bicycle implements Vehicle{
      
    int speed;
    int gear;
      
    // to change gear
    @Override
    public void changeGear(int newGear){
          
        gear = newGear;
    }
      
    // to increase speed
    @Override
    public void speedUp(int increment){
          
        speed = speed + increment;
    }
      
    // to decrease speed
    @Override
    public void applyBrakes(int decrement){
          
        speed = speed - decrement;
    }
      
    public void printStates() {
        System.out.println("speed: " + speed
            + " gear: " + gear);
    }
}
  
class Bike implements Vehicle {
      
    int speed;
    int gear;
      
    // to change gear
    @Override
    public void changeGear(int newGear){
          
        gear = newGear;
    }
      
    // to increase speed
    @Override
    public void speedUp(int increment){
          
        speed = speed + increment;
    }
      
    // to decrease speed
    @Override
    public void applyBrakes(int decrement){
          
        speed = speed - decrement;
    }
      
    public void printStates() {
        System.out.println("speed: " + speed
            + " gear: " + gear);
    }
      
}
class GFG {
      
    public static void main (String[] args) {
      
        // creating an inatance of Bicycle
        // doing some operations
        Bicycle bicycle = new Bicycle();
        bicycle.changeGear(2);
        bicycle.speedUp(3);
        bicycle.applyBrakes(1);
          
        System.out.println("Bicycle present state :");
        bicycle.printStates();
          
        // creating instance of the bike.
        Bike bike = new Bike();
        bike.changeGear(1);
        bike.speedUp(4);
        bike.applyBrakes(3);
          
        System.out.println("Bike present state :");
        bike.printStates();
    }
}