Please comment code

import java.util.ArrayList;

import java.util.Scanner;

abstract class Appointment{

private String description;

private String lastName;

private int hours=0;

private int minutes=0;

public void setDescription(String description){

this.description = description;

}

public void setLastName(String lastName){

this.lastName = lastName;

}

public void setHours(int hours){

this.hours = hours;

}

public void setMinutes(int minutes){

this.minutes = minutes;

}

public String getDescription(){

return this.description;

}

public String getLastName(){

return this.lastName;

}

public int getHours(){

return this.hours;

}

public int getMinutes(){

return this.minutes;

}

abstract public boolean occursOn(int year,int month,int day);

}

class Onetime extends Appointment{

private int year;

private int month;

private int day;

public void setYear(int year) {

this.year=year;

}

public void setMonth(int month) {

this.month=month;

}

public void setDay(int day) {

this.day=day;

}

public int getYear() {

return this.year;

}

public int getMonth() {

return this.month;

}

public int getDay() {

return this.day;

}

@Override

public boolean occursOn(int year, int month, int day) {

if(this.year==year && this.month==month && this.day==day)

return true;

return false;

}

}

class Daily extends Appointment{

@Override

public boolean occursOn(int year, int month, int day) {

// TODO Auto-generated method stub

return true;

}

}

class Monthly extends Appointment{

private int day;

public void setDay(int day) {

this.day=day;

}

public int getDay() {

return this.day;

}

@Override

public boolean occursOn(int year, int month, int day) {

if(this.day==day)

return true;

return false;

}

}

public class TestAppointment {

static Scanner sc= new Scanner(System.in);

public static void main(String[] args) {

ArrayList al = new ArrayList();

System.out.println("How many appointments do you with to make?");

int num = sc.nextInt();

for(int i = 1;i<=num;i++) {

System.out.println("Please make a selection:");

System.out.println("1. One Time Appointment");

System.out.println("2. Daily Appointment");

System.out.println("3. Monthly Appointment");

int selection = sc.nextInt();

al.add(makeAppointment(selection));

}

System.out.println("*******Thank you for making all your appointments*********");

char choice='y';

while(choice=='y') {

System.out.println("What is the date you wish to look up in your Appointment's Calendar");

System.out.print("Enter the month: ");

int month=sc.nextInt();

System.out.print("Enter the day: ");

int day=sc.nextInt();

System.out.print("Enter the year: ");

int year=sc.nextInt();

System.out.println("On "+month+"/"+day+"/"+year+" you have the following appointments:");

for(Appointment a:al) {

boolean isPresent=checkAppointment(a,year,month,day);

if(isPresent) {

System.out.println(a.getDescription()+" with "+a.getLastName()+" at "+a.getHours()+":"+a.getMinutes());

}

}

System.out.println("Do you wish to look up another date?");

choice=sc.next().charAt(0);

}

System.out.println("Thank you for using Appointment Calendar.");

}

public static Appointment makeAppointment(int selection) {

Appointment app=null;

String description="";

String lastName="";

int hours=0;

int minutes = 0;

int day=0;

int year=0;

int month=0;

sc.nextLine();

switch (selection) {

case 1:

Onetime onetime=new Onetime();

System.out.println("What is the description of your appointment?");

description = sc.nextLine();

System.out.println("What is your person's name?");

lastName = sc.nextLine();

System.out.println("What is the year of your appointment?(2017-2018)");

year = sc.nextInt();

System.out.println("What is the month of your appointment?(1-12)");

month = sc.nextInt();

System.out.println("What is the day of your appointment?(1-31)");

day = sc.nextInt();

System.out.println("What is the hour of your appointment?(1-31)");

hours = sc.nextInt();

System.out.println("What is the minutes of your appointment?(1-31)");

minutes = sc.nextInt();

onetime.setDescription(description);

onetime.setHours(hours);

onetime.setLastName(lastName);

onetime.setMonth(month);

onetime.setMinutes(minutes);

onetime.setYear(year);

onetime.setDay(day);

System.out.println("Appointment added with "+lastName+" on "+month+"/"+day+"/"+year+" at "+hours+":"+minutes);

System.out.println();

return onetime;

case 2:

Daily daily = new Daily();

System.out.println("What is the description of your appointment?");

description = sc.nextLine();

System.out.println("What is your person's name?");

lastName = sc.nextLine();

System.out.println("What is the hour of your appointment?(1-31)");

hours = sc.nextInt();

System.out.println("What is the minutes of your appointment?(1-31)");

minutes = sc.nextInt();

daily.setDescription(description);

daily.setHours(hours);

daily.setLastName(lastName);

daily.setMinutes(minutes);

System.out.println("Appointment added with "+lastName+" Daily at "+hours+":"+minutes);

System.out.println();

return daily;

case 3:

Monthly monthly = new Monthly();

System.out.println("What is the description of your appointment?");

description = sc.nextLine();

System.out.println("What is your person's name?");

lastName = sc.nextLine();

System.out.println("What day of the month is your appointment?(1-12)");

day = sc.nextInt();

System.out.println("What is the hour of your appointment?(1-31)");

hours = sc.nextInt();

System.out.println("What is the minutes of your appointment?(1-31)");

minutes = sc.nextInt();

monthly.setDescription(description);

monthly.setHours(hours);

monthly.setLastName(lastName);

monthly.setMinutes(minutes);

monthly.setDay(day);

System.out.println("Appointment added with "+lastName+" Monthly on day "+day+" at "+hours+":"+minutes);

System.out.println();

return monthly;

default:

System.out.println("Invalid Choice..!!");

return app;

}

}

public static boolean checkAppointment(Appointment a, int year, int month, int day) {

return a.occursOn(year, month, day);

}

}