Why protected method is not accessible from subclass?

Question

Consider the following code snippets:

package vehicle;

public abstract class AbstractVehicle {
    protected int speedFactor() {
        return 5;
    }
}

pack         


        

Answer 1

Because protected is visible to the class itself (like private) and its subclass instances. It is not public.

For example,

package vehicles;

public abstract class AbstractVehicle {
    protected int speedFactor() {
        return 5;
    }

    public int getSpeed() {
        return 10*speedFactor(); //accessing speedFactor() "privately"
    }
}

package vehicles.cars;

public class SedanCar extends AbstractVehicle {
    @Override
    protected int speedFactor() { //overriding protected method (just to show that you can do that)
        return 10;
    }

    @Override
    public int getSpeed() {
        return 20*speedFactor(); //this is part of the instance (!!!) therefore it can access speedFactor() protected method too
    }
}

package vehicles.main;

public class Main {
    public static void main(String[] args) {
        AbstractVehicle vehicle = new SedanCar();
        int speed = vehicle.getSpeed(); //accessing public method
        vehicle.speedFactor(); //cannot access protected method from outside class (in another package)
    }
}

The static main() method is not part of the instance, that is why it cannot access the protected method.