Array is not storing objects from database

Question

I m retriving data from database and want to store that data in the form of objects in my arraylist that furthermore can be use in display custom tables.

I have tried the solutions from prev related queries but couldn't solve my problem.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.ArrayList;

public class Appointment {

public int no;
public String patient;
public String doctor;
public String disease;
public String scheduleDay;

public void setNo(int no){
    this.no = no;}

public void setPatient(String patient){
    this.patient = patient;}

public void setDoctor(String doctor){

    this.doctor = doctor;} 

public void setDisease(String disease){

    this.disease = disease;} 

public void setScheduleDay(String scheduleDay){

    this.scheduleDay = scheduleDay;} 

public int getNo(){
    return no;}
public String getPatient(){
    return patient;}
public String getDoctor(){
    return doctor;}
public String getDisease(){
    return disease;}
public String getScheduleDay(){
    return scheduleDay;}


public Appointment(){
    no = 0;
    patient = "not set";
    doctor = "not set";
    disease = "not set";
    scheduleDay = "not set";
}

public Appointment(int no, String patient, String doctor, String 
disease, String scheduleDay){
    setNo(no);
    setPatient(patient);
    setDoctor(doctor);
    setDisease(disease);
    setScheduleDay(scheduleDay);
}

public Appointment (Appointment ap){
    no = ap.no;
    patient = ap.patient;
    doctor = ap.doctor;
    disease = ap.disease;
    scheduleDay = ap.scheduleDay;
} 

public ArrayList<Appointment> appointmentArr() throws 
ClassNotFoundException, SQLException {

 String url = "jdbc:ucanaccess://D:/MC140202550/MC140202550.accdb";
 Connection con = DriverManager.getConnection(url);
 Statement st = con.createStatement();
 String sql = "select * from  Patient, Doctor where Patient.Disease = 
Doctor.Specialization";

 ResultSet rs = st.executeQuery(sql);
 ArrayList<Appointment> appointments = new ArrayList<>();

while(rs.next()==true){
    Appointment ap = new Appointment();
     ap.setPatient(rs.getString(1));
     ap.setDoctor(rs.getString(6));
     ap.setDisease(rs.getString(4));
     ap.setScheduleDay(rs.getString(8));
     int i = 1;
     ap.setNo(i);
     i++;
   appointments.add(ap);  
   System.out.println(ap.getNo() + " " + ap.getPatient() + " " + 
ap.getDoctor() + " " + ap.getDisease() + " " + ap.getScheduleDay());

}
st.executeQuery(sql);

 con.close(); 
 st.close();
 st.close();

return appointments;
} 
}

I want to call this Appointment class in another main class and print the objects stored in array.

public class Main{
public static void main(String args[]){
Main main=new Main();

Appointment ap = new Appointment();
}
}

what array? the only array in your code is String[] args. If you mean your list, you never call the method that populates it, so what exactly are you talking about? — Stultuske
– Stultuske, Commented May 29, 2019 at 6:19
Where is the call to appointment appointmentArr() method? Try adding a call to that method in the constructor of Appointment class. — Sanket Parikh
– Sanket Parikh, Commented May 29, 2019 at 6:23
And just for the record: an array is ot the same as an ArrayList. And: separate concerns. The process of reading objects from a DB has nothing to do with that class itself. The code for reading Appointment objects should sit in its own distinct class. It doesnt belong into the Appointment class! — GhostCat
– GhostCat, Commented May 29, 2019 at 6:33
Plus: format/indenting matters. Make sure each line is correctly indented. Not only for us here, but also when you write code for your own. You want your code to be as easy to read as possible. Yours is not, mainly because of the inconsistent indentation. — GhostCat
– GhostCat, Commented May 29, 2019 at 6:45

MD Ruhul Amin · Accepted Answer · 2019-05-29 06:26:28Z

3

you need to call appointmentArr() from main method and assign it into a variable, then print it. for example:

public class Main{
   public static void main(String args[]){

    Appointment ap = new Appointment();
    List<Appointment> list = ap.appointmentArr();
    // now you can iterate over list and print it.
    for(Appointment ap: list){
        System.out.println(ap.getNo() + " " + ap.getPatient() + " " +
                ap.getDoctor() + " " + ap.getDisease() + " " + ap.getScheduleDay());
    }

   }
}

answered May 29, 2019 at 6:26

MD Ruhul Amin

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