Examples of Access Protection

Now let's try to directly access the fields from another class and see what happens:

class CarTest8 {

  public static void main(String args[]) {
    
    Car c = new Car("New York A45 636", 100.0);
    
    c.licensePlate = "New York A45 636";
    c.speed = 0.0;
    c.maxSpeed = 123.45;
    
    System.out.println(c.licensePlate + " is moving at " + c.speed + 
     " kilometers per hour.");

    c.floorIt();
    
    System.out.println(c.licensePlate + " is moving at " + c.speed + 
     " kilometers per hour.");

  }
    
}

Here's what happens when you try to compile it against the revised Car class:

% javac Car.java
% javac CarTest8.java
CarTest8.java:7: Variable licensePlate in class Car not accessible from class CarTest8.
    c.licensePlate = "New York A45 636";
     ^
CarTest8.java:8: Variable speed in class Car not accessible from class CarTest8.
    c.speed = 0.0;
     ^
CarTest8.java:9: Variable maxSpeed in class Car not accessible from class CarTest8.
    c.maxSpeed = 123.45;
     ^
CarTest8.java:11: Variable licensePlate in class Car not accessible from class CarTest8.
    System.out.println(c.licensePlate + " is moving at " + c.speed +
                        ^
CarTest8.java:11: Variable speed in class Car not accessible from class CarTest8.
    System.out.println(c.licensePlate + " is moving at " + c.speed +
                                                            ^
CarTest8.java:16: Variable licensePlate in class Car not accessible from class CarTest8.
    System.out.println(c.licensePlate + " is moving at " + c.speed +
                        ^
CarTest8.java:16: Variable speed in class Car not accessible from class CarTest8.
    System.out.println(c.licensePlate + " is moving at " + c.speed +
                                                            ^
7 errors
%