Reading a text file (which i already know) and then displaying it in a GUI?

Question

Okay so my program appears to be very basic, I have one class that inputs the students to a text file and this class has to read them, display them in a GUI so the user can pic which student the want and then a remove method to delete the students from the text file. The problem is that this is way more complex than the stuff that I have ever studied, and I am really in need of help, here is my code for the removing students class:

import java.io.*;
import java.awt.*;
import java.awt.event.*;

public class StudentsRemove extends Frame implements ActionListener
{
    String messsage="";
    Button buttonView, buttonClose, buttonRemove; // Implements all the buttons 
    Label labelAnswer; // Implements all the different text boxes
    TextField textAnswer;

    StudentsRemove(String name)
    {
        super(name);
        setLayout(new GridLayout(7,7));

        labelAnswer = new Label("Remove Student: ");
        textAnswer = new TextField(""); 
        buttonView = new Button("VIEW STUDENTS");
        buttonRemove = new Button("REMOVE");
        buttonClose = new Button("CLOSE");

        add(labelAnswer);
        add(textAnswer);
        add(buttonView);
        add(buttonRemove);
        add(buttonClose);
        setVisible(true);

        buttonView.addActionListener(this);
        buttonRemove.addActionListener(this);
        buttonClose.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) 
    {
         String s="";

        String str = e.getActionCommand();
        if(str.equals("VIEW STUDENTS"))
        {

        try 
        {
            BufferedReader BuffRe = new BufferedReader(new FileReader("Students.txt"));
            StringBuilder StrBu = new StringBuilder();
            String line = BuffRe.readLine(); 

            while (line != null)
            {
                StrBu.append(line);
                StrBu.append(System.lineSeparator());
                line = BuffRe.readLine();
                //numStudents++;
            }
                    String everything = StrBu.toString();
                    BuffRe.close();
        }   

        catch(Exception z)
        {
            System.out.println("The Exception Is : " +z);
        }

        }
     }

}

I need help displaying them in a GUI once I've read the entire program, and then allowing the user to select one of the students and removing them. I know it's a lot but I am completely lost and don't have an "extensive" knowledge of programming.

Thanks in advance guys.

Cyla.

Answer 1

Start by declaring a JList and ListModel instance variables...

private JList studentList;
private DefaultListModel model;

This is what will be used to display your information and allow the user to interact with.

Create some methods to update the model...

public void addStudent(String student) {
    model.addElement(student);
}

public void deleteStudent(String student) {
    model.removeElement(student);
}

Create methods to read and write the student information from and to disk...

public List<String> loadStudents() throws IOException {
    List<String> students = new ArrayList<>(25);
    try (BufferedReader br = new BufferedReader(new FileReader("Students.txt"))) {

        String student = null;
        while ((student = br.readLine()) != null) {
            students.add(student);
        }

    } finally {
    }
    return students;
}

public void saveStudents(List<String> students) throws IOException {
    try (BufferedWriter bw = new BufferedWriter(new FileWriter("Students.txt"))) {

        for (String student : students) {
            bw.write(student);
            bw.newLine();
        }
        bw.flush();

    } finally {
    }
}

Then load the student information from the file into the model...

protected void save() {
    try {
        List<String> students = loadStudents();
        model = new DefaultListModel();
        for (String student : students) {
            model.addElement(student);
        }
    } catch (IOException ex) {
        JOptionPane.showMessageDialog(this, "Could not read students.txt: " + ex.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
    }
    studentList.setModel(model);
}

And write a method to save the information from the model to disk...

protected void save() {
    List<String> students = new ArrayList<>(model.getSize());
    for (int index = 0; index < model.getSize(); index++) {
        students.add((String)model.get(index));
    }

    try {
        saveStudents(students);
    } catch (IOException ex) {
        JOptionPane.showMessageDialog(this, "Could not write students.txt: " + ex.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
    }
}

Now, obviously, you need to create the JList and add it your UI, but I'll leave that up to you.

Take a look at Creating a GUI With JFC/Swing and How to Use Lists for more details