An interface is the sketch of your real class

EXAMPLE (4 STEPS)

1. You make the interface; WHAT KIND OF CLASS SHOULD I MAKE?
   package Interface;
   
   public interface InterfaceClass {
   
      // constant declarations, if any
   
      // method signatures
      
      // An enum with values RIGHT, LEFT
      int turn(String direction,
               double radius,
               double startSpeed,
               double endSpeed);
      int changeLanes(String direction,
                      double startSpeed,
                      double endSpeed);
      int signalTurn(String direction,
                     boolean signalOn);
      int getRadarFront(double distanceToCar,
                        double speedOfCar);
      int getRadarRear(double distanceToCar,
                       double speedOfCar);
   
      // more method signatures
   }

2. You create the main class which EXTENDS the abstract class
   package Interface;
   
   public class ImplementationClass implements InterfaceClass {
   	
   }

3. add unimplemented methods in REAL class
4. RESULT
   

   Interface package Interface; public interface InterfaceClass { // constant declarations, if any // method signatures // An enum with values RIGHT, LEFT int turn(String direction, double radius, double startSpeed, double endSpeed); int changeLanes(String direction, double startSpeed, double endSpeed); int signalTurn(String direction, boolean signalOn); int getRadarFront(double distanceToCar, double speedOfCar); int getRadarRear(double distanceToCar, double speedOfCar); // more method signatures }

   IMPLEMENTATION CLASS package Interface; public class ImplementationClass implements InterfaceClass { @Override public int turn(String direction, double radius, double startSpeed, double endSpeed) { // TODO Auto-generated method stub return 0; } @Override public int changeLanes(String direction, double startSpeed, double endSpeed) { // TODO Auto-generated method stub return 0; } @Override public int signalTurn(String direction, boolean signalOn) { // TODO Auto-generated method stub return 0; } @Override public int getRadarFront(double distanceToCar, double speedOfCar) { // TODO Auto-generated method stub return 0; } @Override public int getRadarRear(double distanceToCar, double speedOfCar) { // TODO Auto-generated method stub return 0; } }