simple demo@polymorphism,inheritance,overriding,overloading

/*
a basic example of polymorphism,inheritance, overloading and overriding
*/
import java.util.Scanner;

class Doctor{
    boolean worksAtHospital;

    public void treatPatient(){
        System.out.print("doctor\n he is now");
        System.out.println(" gonna give you medicine :) ");
    }
}

class surgeon extends Doctor{
    public void treatPatient(){ // overriding
        System.out.print("surgeon\n he is now");
        System.out.println(" doing operation!");
    }
}

class familyDoctor extends Doctor{
    boolean makesHouseCalls;

    public void treatPatient(){ // overriding
        System.out.print("family doctor\n he is now");
        System.out.println(" giving advice..");
    }
}

class goToDoctor{
    public void treatPatient(Doctor d){ // d is an object of type Doctor. d can also be a subclass of Doctor
                                        //this is overloading (note: overloading has nothing to do with polymorphism or inheritance by itself)
        d.treatPatient();
    }
}

class imUnwell{

    public static void main(String[] args){
        Scanner input=new Scanner(System.in);
        int whichDoctor;

        System.out.println(" who do you want to treat you?\n 1.Doctor?\n 2.Surgeon?\n 3.familyDoctor?");
        whichDoctor=input.nextInt();

        System.out.print("option entered: " + whichDoctor + ">");
        goToDoctor x = new goToDoctor();

        Doctor doc = new Doctor();
        Doctor sur = new surgeon(); // polymorphism : doctor is superclass, surgeon is subclass
        Doctor fam = new familyDoctor(); // polymorphism : doctor is superclass, family doctor is subclass

        if(whichDoctor==1)
        x.treatPatient(doc); // passing object as argument
        else if(whichDoctor==2)
        x.treatPatient(sur);
        else if(whichDoctor==3)
        x.treatPatient(fam);

    }
}