java - 数组不存储数据库中的对象

Question

我正在从数据库中检索数据，并希望以对象的形式将该数据存储在我的数组列表中，并且可以在显示自定义表格中使用。

我已尝试了之前相关查询中的解决方案，但无法解决我的问题。

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;
} 
}

我想在另一个主类中调用这个 Appointment 类并打印存储在数组中的对象。

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

Appointment ap = new Appointment();
}
}

Answer 1

您需要从 main 方法调用 appointmentArr() 并将其分配给变量，然后打印它。例如:

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());
    }

   }
}