The document describes a Java program designed to manage patient data using multiple classes: an abstract class 'patient', a concrete class 'patientimpl', and a comparator class 'patientcomparator'. The main driver class facilitates user interaction to add patients, retrieve the next patient by priority, and exit the program. Key functionalities include storing patient details, comparing patients based on priority, and ordering them in a priority queue.

1. Here is how the code works
1. Patient.java is an Abstract Class which contains the required attributes and a constructor for
initializing the Patient object
2. PatientImpl.java is a class which extends the Abstract class Patient.java and contains a
constructor which makes a call to the superclass and initializes the superclass with passed
arguments
3. PatientComparator.java is a class which implements the comparator interface and specfies the
criteria for comparing two Patient objects
4. Main.java drives the complete program by providing a menu to the user with the three options
that is for adding a patient, finding the next highest priority patient to be served and exiting the
program
Please find the code as follows:-
Patient.java Code:-
package com.chegg.patient;
import java.util.Date;
abstract class Patient {
private String name;
private Date dob;
private Date admission;
private String complaint;
private int priority;
public Patient(String name, Date dob, Date admission, String complaint, int priority) {
this.name = name;
this.dob = dob;
this.admission = admission;
this.complaint = complaint;
this.priority = priority;
}
public String toString() {
return this.name + this.dob + this.admission + this.complaint + this.priority;
}
public String getName() {
return name;
}
public void setName(String name) {

2. this.name = name;
}
public Date getDob() {
return dob;
}
public void setDob(Date dob) {
this.dob = dob;
}
public Date getAdmission() {
return admission;
}
public void setAdmission(Date admission) {
this.admission = admission;
}
public String getComplaint() {
return complaint;
}
public void setComplaint(String complaint) {
this.complaint = complaint;
}
public int getPriority() {
return priority;
}
public void setPriority(int priority) {
this.priority = priority;
}
}
PatientImpl.java Code
package com.chegg.patient;
import java.util.Date;
public class PatientImpl extends Patient {
public PatientImpl(String name, Date dob, Date admission, String complaint, int priority) {
super(name, dob, admission, complaint, priority);
}
}
PatientComparator.java Code

3. package com.chegg.patient;
import java.util.Comparator;
public class PatientComparator implements Comparator {
@Override
public int compare(Patient arg0, Patient arg1) {
if(arg0.getPriority() == arg1.getPriority()){
if(arg0.getAdmission().compareTo(arg1.getAdmission())==-1){
return -1;
}
else
return 1;
}
if(arg0.getPriority() comparator = new PatientComparator();
PriorityQueue Pq = new PriorityQueue(10, comparator);
while (true) {
System.out.println("1. Enter New Patient Data");
System.out.println("2. Retrieve Next Patient to treat");
System.out.println("3. Exit");
choice = sc.nextInt();
sc.nextLine();
switch (choice) {
case 1: {
System.out.println("Enter Name");
name = sc.nextLine();
System.out.println("Enter Date of birth in format yyyy-mm-dd");
String dob_String = sc.next();
dob = parseDate(dob_String);
admission = new Date();
System.out.println("Enter Complaint");
sc.nextLine();
complaint = sc.nextLine();
System.out.println("Enter Priority");
priority = sc.nextInt();
Patient myPatient = new PatientImpl(name, dob, admission, complaint, priority);
Pq.add(myPatient);
System.out.println(myPatient.toString());

4. break;
}
case 2: {
if (Pq.size() > 0) {
Patient nextPatient = Pq.remove();
System.out.println(nextPatient.toString());
}else
System.out.println("No Patients Pending");
break;
}
case 3: {
if(Pq.size()>0){
System.out.println("Patients are pending in the queue");
continue;
}else{
sc.close();
System.exit(0);
}
}
}
}
}
public static Date parseDate(String date) {
try {
return new SimpleDateFormat("yyyy-MM-dd").parse(date);
} catch (ParseException e) {
return null;
}
}
}
Solution
Here is how the code works
1. Patient.java is an Abstract Class which contains the required attributes and a constructor for
initializing the Patient object

5. 2. PatientImpl.java is a class which extends the Abstract class Patient.java and contains a
constructor which makes a call to the superclass and initializes the superclass with passed
arguments
3. PatientComparator.java is a class which implements the comparator interface and specfies the
criteria for comparing two Patient objects
4. Main.java drives the complete program by providing a menu to the user with the three options
that is for adding a patient, finding the next highest priority patient to be served and exiting the
program
Please find the code as follows:-
Patient.java Code:-
package com.chegg.patient;
import java.util.Date;
abstract class Patient {
private String name;
private Date dob;
private Date admission;
private String complaint;
private int priority;
public Patient(String name, Date dob, Date admission, String complaint, int priority) {
this.name = name;
this.dob = dob;
this.admission = admission;
this.complaint = complaint;
this.priority = priority;
}
public String toString() {
return this.name + this.dob + this.admission + this.complaint + this.priority;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getDob() {
return dob;

6. }
public void setDob(Date dob) {
this.dob = dob;
}
public Date getAdmission() {
return admission;
}
public void setAdmission(Date admission) {
this.admission = admission;
}
public String getComplaint() {
return complaint;
}
public void setComplaint(String complaint) {
this.complaint = complaint;
}
public int getPriority() {
return priority;
}
public void setPriority(int priority) {
this.priority = priority;
}
}
PatientImpl.java Code
package com.chegg.patient;
import java.util.Date;
public class PatientImpl extends Patient {
public PatientImpl(String name, Date dob, Date admission, String complaint, int priority) {
super(name, dob, admission, complaint, priority);
}
}
PatientComparator.java Code
package com.chegg.patient;
import java.util.Comparator;
public class PatientComparator implements Comparator {
@Override

7. public int compare(Patient arg0, Patient arg1) {
if(arg0.getPriority() == arg1.getPriority()){
if(arg0.getAdmission().compareTo(arg1.getAdmission())==-1){
return -1;
}
else
return 1;
}
if(arg0.getPriority() comparator = new PatientComparator();
PriorityQueue Pq = new PriorityQueue(10, comparator);
while (true) {
System.out.println("1. Enter New Patient Data");
System.out.println("2. Retrieve Next Patient to treat");
System.out.println("3. Exit");
choice = sc.nextInt();
sc.nextLine();
switch (choice) {
case 1: {
System.out.println("Enter Name");
name = sc.nextLine();
System.out.println("Enter Date of birth in format yyyy-mm-dd");
String dob_String = sc.next();
dob = parseDate(dob_String);
admission = new Date();
System.out.println("Enter Complaint");
sc.nextLine();
complaint = sc.nextLine();
System.out.println("Enter Priority");
priority = sc.nextInt();
Patient myPatient = new PatientImpl(name, dob, admission, complaint, priority);
Pq.add(myPatient);
System.out.println(myPatient.toString());
break;
}
case 2: {
if (Pq.size() > 0) {

8. Patient nextPatient = Pq.remove();
System.out.println(nextPatient.toString());
}else
System.out.println("No Patients Pending");
break;
}
case 3: {
if(Pq.size()>0){
System.out.println("Patients are pending in the queue");
continue;
}else{
sc.close();
System.exit(0);
}
}
}
}
}
public static Date parseDate(String date) {
try {
return new SimpleDateFormat("yyyy-MM-dd").parse(date);
} catch (ParseException e) {
return null;
}
}
}