GUI display info from ArrayList using JButton, JTextArea and showInputDialog

Question

Does anyone know how to iterate through an ArrayList and retrieve an item by using the actionPerformed method?

Basically I'm trying to let the user click a button. After that button is clicked a showInputDialog appears, then the user for instance enters the id number of a student. All that student's details will appear in a jtextArea or showMessageDialog box.

Can anyone show me? here is the actual code I was just using the student as example.

import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*; 

public class DepotAdmin 
{
    private ArrayList<Vehicle> DepoVehicle = new ArrayList<Vehicle>(); 
    public DepotAdmin(String hd,String c, String m, String d,Fuel p,int EngSize)
    {
          DepoVehicle = new ArrayList<Vehicle>();

    }


     private void setupDepot(){
        //DepotArraylist vehicles = new DepotArraylist("1111","1111","1111","1111",new Fuel(""),0);

        DepoVehicle.add(new Car("BobMart","567890","Volvo","04/06/2014", new Fuel("Diesel"),6000));
        DepoVehicle.add(new Car("BobMart","465783","BMW","12/052014", new Fuel ("Petrol"), 8000));
        DepoVehicle.add(new Car("BobMart","348709","Ford","13/08/2014",new Fuel ("Petrol"), 3000));
        DepoVehicle.add(new Car("BobMart","145367","Lexus","18/08/2015",new Fuel ("Diesel"), 2000));
        DepoVehicle.add(new RentableCar("BobMart","847469","Citreon","08/07/2015",new             Fuel("Diesel"),1000));
        Car car1 = new Car("BobMart","567890","Volvo","04/06/2014", new Fuel("Diesel"),6000);



    public Vehicle byMake(String make)
    {
            String st[]=DepoVehicle.toArray(new String[DepoVehicle.size()]); 
              for ( Vehicle v : DepoVehicle)
         if (v.getMake().equals(make)){
            return v;
            }
           return null;

      }




    private JFrame Depot ;
    private JMenu Vehicles;
    private JMenu searchVehicle;    
    private JMenu rentVehicle;    
    private JMenu returnVehicle;
    private JMenuItem vehicles1;
    private JMenuItem searchVehicle1;
    private JMenuItem rentVehicle1;
    private JMenuItem returnVehicle1; 
    private JTextArea textArea;
    private JMenuBar menubar;
    private JList vList;
    private ResDepotAdmin listener;
    private ResDepotAdmin listener1;
    private ResDepotAdmin listener2;
    private ResDepotAdmin listener3;
    private JLabel repeatLabel;
    private JTextField inputText;
    private JPanel textPanel;
    public DepotAdmin(){
    //creating the frame to place the menu bar
    Depot = new JFrame ("Depot");
    //creating the menubar to place the menu items
    menubar = new JMenuBar();
    //set the menu bar in the frame
    Depot.setJMenuBar(menubar);
    //set the menus on the menu bar
    Vehicles = new JMenu ("vehicles");
    menubar.add(Vehicles);
    searchVehicle = new JMenu ("search");
    menubar.add(searchVehicle);
    rentVehicle = new JMenu ("rent");
    menubar.add(rentVehicle);
    returnVehicle = new JMenu ("return");
    menubar.add(returnVehicle);
    //set the menu items on the menues
    vehicles1 = new JMenuItem ("Vehicle List");
    Vehicles.add(vehicles1);
    searchVehicle1 = new JMenuItem ("Search Vehicle");
    searchVehicle.add(searchVehicle1);
    rentVehicle1 = new JMenuItem ("Rent Vehicle");
    rentVehicle.add(rentVehicle1);
    returnVehicle1 = new JMenuItem ("Return Vehicle");
    returnVehicle.add(returnVehicle1);
    //data display section
    textArea = new JTextArea(70,70);
    textPanel = new JPanel();
    //add textarea to panel
    textPanel.add(textArea);
    //add panel to frame
    Depot.add((textPanel),BorderLayout.CENTER);
    listeners to respond to click by uaer
    listener = new ResDepotAdmin();
    listener1 = new ResDepotAdmin();
    listener2 = new ResDepotAdmin();
    listener3 = new ResDepotAdmin();
    vehicles1.addActionListener(listener);
    searchVehicle1.addActionListener(listener1);
    rentVehicle1.addActionListener(listener2);
    returnVehicle.addActionListener(listener3);


    String vehicleMake = "make";
    //JOptionPane.showInputDialog(searchVehicle1,"Enter vehicle make");
    //set the size of the frame
    Depot.setSize(600,600);
    //aet the visibility of the frame
    Depot.setVisible(true);
    //prevent the running the the program on exit
    Depot.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



         }
         public class ResDepotAdmin implements ActionListener
    {


       private String make; 
     private void setupDepot(){
        DepotArraylist vehicles = new DepotArraylist("1111","1111","1111","1111",new Fuel(""),0);
        vehicles.addVehicle(new Car("BobMart","567890","Volvo","04/06/2014", new Fuel("Diesel"),6000));
        vehicles.addVehicle(new Car("BobMart","465783","BMW","12/052014", new Fuel ("Petrol"), 8000));
        vehicles.addVehicle(new Car("BobMart","348709","Ford","13/08/2014",new Fuel ("Petrol"), 3000));
        vehicles.addVehicle(new Car("BobMart","145367","Lexus","18/08/2015",new Fuel ("Diesel"), 2000));
        vehicles.addVehicle(new RentableCar("BobMart","847469","Citreon","08/07/2015",new Fuel("Diesel"),1000));
        Car car1 = new Car("BobMart","567890","Volvo","04/06/2014", new Fuel("Diesel"),6000);



}


         public Vehicle findVehicle(String make)
          {
           for (Vehicle dv : DepoVehicle)
             if (dv.getMake().equals(make))
            return dv;
              return null;
            }


             public void actionPerformed(ActionEvent e)
             {
                       //DepotAdmin DepoVehicle = new DepotAdmin("null","null","null","null",new Fuel(""),0);

                       ArrayList<Vehicle> DepoVehicle = new ArrayList<Vehicle>();
                               DepoVehicle.add(new Car("BobMart","567890","Volvo","04/06/2014",    new Fuel("Diesel"),6000));
                               DepoVehicle.add(new Car("BobMart","348709","Ford","13/08/2014",new Fuel ("Petrol"), 3000));


                     if ( e.getSource() == vehicles1){
                     textArea.append(DepoVehicle.toString()+"\n"+"\n");
                     }


                     String make = JOptionPane.showInputDialog(null,"Enter vehicle make");

                      if (e.getSource()== searchVehicle1){

                           for ( Vehicle v : DepoVehicle){ if (v.getMake().equals(make)){
                                                        textArea.append(make);

                                                                  }
                                                     }

                     }
            }
      }
}

Answer 1

I wasn't really sure how to interpret the fact that you have a message about a car, but you want the student as an input. So I changed it around a little. Make your changes accordingly.

I just looped, and if the student Id matches the input, I appended the student to the text area

public void actionPerformed{

   String stuId = JOptionPane.showInputDialog(null,"Enter Student ID");

   for (Student student : pupils){
       if (student.getId().equals(stuId)){
           textArea.append(student);
           break;
       }
   }
}

---

• Also, I noticed you have an actionPerformed inside the main method. Are you trying to create a GUI program? Becuase at this point, your code is far from accomplishing it.

• You also seem to have a method inside of a main which is a no no. You're code in no way compiles. Please post a compileable program so we can see exactly what you trying to accomplish. Because the code in your post is rubbish.

---

Another HUGE fault I noticed is here

    String name;
    String id;
    public Student (String n, String i) {
        n = name;
        i = id;
    }

Your constructor is wrong. n = name does nothing. Instead you want

    name = n;
    id = i;

---

Also Student take a String input, but you're trying to add an int . Maybe that was just for an SSCCE attempt, but it were getting those input from a text field, it would work, but if you're hard coding it in, they need to be String.

    pupils.add(new Student("james", "2345"));
    pupils.add(new Student ("taylor", "5768"));
    pupils.add(new Student("andy", "9874"));

---

Also for your Student class if you want the String representation of the Student object, you should @Override the toString() method, something like this

    public String toString() {
       //am i wrong here?  
        return "Student Name: " + name + ", ID: " + id;
    }

---

Here's a simple complete runnable program so you can see how everything fits together. Examine it to see where you may be going wrong. Feel free to ask questions.

import java.awt.BorderLayout;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;

public class StudentGUI extends JFrame {

    private JTextArea jtaStudent = new JTextArea(10, 30);
    private JButton showStudents = new JButton("Show Students");
    ArrayList<Student> pupils = new ArrayList<>();

    public StudentGUI() {
        pupils.add(new Student("james", "2345"));
        pupils.add(new Student("taylor", "5768"));
        pupils.add(new Student("andy", "9874"));

        add(showStudents, BorderLayout.SOUTH);
        add(jtaStudent, BorderLayout.CENTER);

        showStudents.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                for (Student student : pupils) {
                    jtaStudent.append(student + "\n");
                }
            }
        });
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new StudentGUI();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);

            }
        });
    }
}

class Student {
    String name;
    String id;

    public Student(String n, String i) {
        name = n;
        id = i;
    }

    public String getName() {
        return name;
    }

    public String getId() {
        return id;
    }

    public String toString() {
        // am i wrong here?
        return "Student Name: " + name + ", ID: " + id;
    }
}

Answer 2

You created a constructor for:

public Students(parameter, parameter){}

, but you did not create a constructor for:

public Student(){}

Normally, if you do not create any constructors yourself, the compiler will create a no-arg cosntructor for you, but when you create any constructors yourself, you will need to create a no-arg constructor yourself. Hope this helps.