Institute of Information Science - University of Miskolc

Similar to classes, but they does not contain any method implementations. An interface can extend other interfaces. Vehicle is a general interface, Car extends from a Vehicle it has more specific functions, similar to Motorcycle.

Vehicle.java

public interface Vehicle
{
 public void hasWheels();
 public void hasEngine();
}

Car.java

public interface Car extends Vehicle
{
 public void hasDoors();
 public void hasAirbags();
 public void hasRoof();
}

Motorcycle.java

public interface Motorcycle extends Vehicle
{
 public void hasPedal();
 public void hasHandlebars();
 public void hasStand();
}

Exercise 1.

• Create a BMW class which implements Car interface.
• Create a Skoda class implements car interface.

public class TryItOut {
public static void main(String[] args) {
              // creating a car array with 10 elements
	Car car[] = new Car[10];
	// create Skodas and BMWs (depending on the i-th index)
	for(int i=0; i < 10; i++) {
		if(i%2 == 0) {
			car[i] = new Skoda();
		} else {
			car[i] = new BMW();
		}
	}
	// call hasAirbags() method on each instance
	for(int i=0; i < 10; i++) {
		car[i].hasAirbags();
	}
}
}