College Billing System - Java

Question

I developed a college fee report generator application using Java with internet as referance,but now I need you guys help in making it more obvious and a sturdy application as I am a rookie to Java Swing.

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.FileWriter;


public class College extends Frame {

    JLabel l1, l2, l3, l4,
            l5, l6, l7, l8,
            l9, l10, l12, l13,
            l14, l11, l15;

    JTextField tf1, tf2, tf3,
            tf4, tf5, tf6,
            tf7, tf8, tf9,
            tf10;

    JTextArea area2, area1;

    JRadioButton rb1, rb2, rb3,
            rb4, rb5, rb6,
            rb7;

    JFileChooser f1;

    // Default constructor to
    // initialize the parameters
    College()
    {


        l1 = new JLabel("Fee Report");
        l1.setBounds(550, 100, 250, 20);

        l2 = new JLabel(
                "Name of the Student:");
        l2.setBounds(50, 150, 250, 20);

        tf1 = new JTextField();
        tf1.setBounds(250, 150, 250, 20);

        l3 = new JLabel(
                "Name of the Father:");
        l3.setBounds(50, 200, 250, 20);

        tf2 = new JTextField();
        tf2.setBounds(250, 200, 250, 20);

        l4 = new JLabel("Roll Number:");
        l4.setBounds(50, 250, 250, 20);

        tf3 = new JTextField();
        tf3.setBounds(250, 250, 250, 20);

        l5 = new JLabel("Email ID:");
        l5.setBounds(50, 300, 250, 20);

        tf4 = new JTextField();
        tf4.setBounds(250, 300, 250, 20);

        l6 = new JLabel("Contact Number:");
        l6.setBounds(50, 350, 250, 20);

        tf5 = new JTextField();
        tf5.setBounds(250, 350, 250, 20);

        l7 = new JLabel("Address:");
        l7.setBounds(50, 400, 250, 20);

        area1 = new JTextArea();
        area1.setBounds(250, 400, 250, 90);

        l9 = new JLabel("Gender:");
        l9.setBounds(50, 500, 250, 20);

        JRadioButton r5
                = new JRadioButton(" Male");
        JRadioButton r6
                = new JRadioButton(" Female");

        r5.setBounds(250, 500, 100, 30);
        r6.setBounds(350, 500, 100, 30);

        ButtonGroup bg = new ButtonGroup();
        bg.add(r5);
        bg.add(r6);

        l10 = new JLabel("Nationality:");
        l10.setBounds(50, 550, 250, 20);

        String nationality[]
                = { "Indian","Other"};

        final JComboBox cb3
                = new JComboBox(nationality);

        cb3.setBounds(250, 550, 250, 20);

        l11 = new JLabel(
                "Year of passing 10th");
        l11.setBounds(50, 600, 250, 20);

        String language[]
                = { "2017","2016", "2015", "2014" ,"2013","2012"};

        final JComboBox cb1
                = new JComboBox(language);

        cb1.setBounds(250, 600, 90, 20);

        l12 = new JLabel(
                "Year of passing 12th");
        l12.setBounds(50, 650, 250, 20);

        String languagess[]
                = { "2020","2019", "2018", "2017","2016","2015" };


        l13 = new JLabel(
                "Percentage Secured in 10th:");
        l13.setBounds(50, 700, 250, 20);

        tf7 = new JTextField();
        tf7.setBounds(250, 700, 250, 20);

        l14 = new JLabel("Percentage Secured in 12th:");
        l14.setBounds(50, 750, 250, 20);

        tf8 = new JTextField();
        tf8.setBounds(250, 750, 250, 20);

        ImageIcon i2 = new ImageIcon("2.png");
        JLabel l15
                = new JLabel("", i2, JLabel.CENTER);

        l15.setBounds(900, 50, 600, 200);

        final JComboBox cb2
                = new JComboBox(languagess);

        cb2.setBounds(250, 650, 90, 20);
        l8 = new JLabel(
                "Groups Offered here are:");
        l8.setBounds(800, 150, 250, 20);

        rb1 = new JRadioButton("Engineering");
        rb1.setBounds(550, 150, 100, 30);

        rb2 = new JRadioButton("Arts");
        rb2.setBounds(650, 150, 100, 30);

        ButtonGroup bg1 = new ButtonGroup();

        bg1.add(rb1);
        bg1.add(rb2);

        rb3 = new JRadioButton("Hosteller / Residential ");
        rb3.setBounds(550, 200, 100, 30);

        rb4 = new JRadioButton("Day-Scholar");
        rb4.setBounds(650, 200, 120, 30);

        ButtonGroup bg2 = new ButtonGroup();
        bg2.add(rb3);
        bg2.add(rb4);

        String languages[]
                = { "CSE", "ECE", "EEE","IT","AERO","MCT","AUTO","PROD","TEXT","CIVIL", "MECH" };
        final JComboBox cb
                = new JComboBox(languages);
        cb.setBounds(800, 200, 90, 20);

        final JLabel label
                = new JLabel();
        label.setBounds(600, 430, 500, 30);
        JButton b = new JButton("Show");
        b.setBounds(1000, 300, 80, 30);

        final DefaultListModel<String> li1
                = new DefaultListModel<>();

        li1.addElement("CSE(2, 50, 000)");
        li1.addElement("ECE(2, 50, 000)");
        li1.addElement("EEE(2, 50, 000)");
        li1.addElement("IT(2, 50, 000)");
        li1.addElement("AERO(2, 50, 000)");
        li1.addElement("MCT(3, 50, 000)");
        li1.addElement("AUTO(3, 50, 000)");
        li1.addElement("CHEMICAL(3, 50, 000)");
        li1.addElement("BIOTECH(3, 50, 000)");
        li1.addElement("CIVIL(3, 50, 000)");
        li1.addElement("MECH(3, 50, 000)");

        final JList<String> list1
                = new JList<>(li1);

        list1.setBounds(600, 300, 125, 125);

        DefaultListModel<String> li2
                = new DefaultListModel<>();

        li2.addElement(
                "2 SHARE(1, 50, 000)");
        li2.addElement(
                "3 SHARE(1, 40, 000)");
        li2.addElement(
                "5 SHARE(1, 20, 000)");
        li2.addElement(
                "8 SHARE(1, 10, 000)");
        li2.addElement(
                "BUS(40, 000)");
        li2.addElement("SELF(0)");

        final JList<String> list2
                = new JList<>(li2);
        list2.setBounds(
                800, 300, 125, 125);

        JButton Receipt
                = new JButton("Generate Receipt");
        Receipt.setBounds(600, 490, 150, 30);
        JButton b2 = new JButton("Reset");
        b2.setBounds(750, 490, 150, 30);
        JButton Print = new JButton("Print");
        Print.setBounds(900, 490, 150, 30);

        area2 = new JTextArea();
        area2.setBounds(600, 540, 450, 240);

        add(l1);
        add(l2);
        add(l3);
        add(l4);
        add(l5);
        add(l6);
        add(l7);
        add(l8);
        add(l9);
        add(l10);
        add(l11);
        add(l12);
        add(l13);
        add(l14);
        add(tf1);
        add(tf2);
        add(tf3);
        add(tf4);
        add(tf5);
        add(tf7);
        add(tf8);
        add(area1);
        add(area2);
        add(l15);
        add(rb1);
        add(rb2);
        add(rb3);
        add(rb4);
        add(r5);
        add(r6);
        add(cb);
        add(cb3);
        add(cb1);
        add(cb2);
        add(list1);
        add(list2);
        add(b);
        add(label);
        add(Receipt);
        add(b2);
        add(Print);

        b.addActionListener(new ActionListener() {

            // Method to display the data
            // entered in the text fields
            public void actionPerformed(ActionEvent e)
            {
                String data = "";
                if (list1.getSelectedIndex() != -1) {
                    data = "You had selected the Group:"
                            + list1.getSelectedValue();
                    label.setText(data);
                }
                if (list2.getSelectedIndex() != -1) {
                    data += " and Hostel with the "
                            + "facility of: ";

                    for (Object frame :
                            list2.getSelectedValues()) {
                        data += frame + " ";
                    }
                }
                label.setText(data);
            }
        });

        // Reset the text fields
        b2.addActionListener(
                new ActionListener() {
                    public void actionPerformed(
                            ActionEvent e)
                    {
                        area2.setText("");
                        area1.setText(" ");
                        tf1.setText("");
                        tf2.setText("");
                        tf3.setText("");
                        tf4.setText("");
                        tf5.setText("");
                        tf6.setText(" ");
                    }
                });
        Print.addActionListener(
                new ActionListener() {
                    public void actionPerformed(
                            ActionEvent e)
                    {
                        try {
                            area2.print();
                        }
                        catch (java.awt.print
                                .PrinterException a) {
                            System.err.format(
                                    "NoPrinter Found",
                                    a.getMessage());
                        }
                    }
                });
        Receipt.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
            {

                area2.setText(
                        "--------------------"
                                + "-----------XYZ EDUCATIONAL INSTITUTIONS----"
                                + "--------------------"
                                + "----------"
                                + "---------\n");

                area2.setText(area2.getText()
                        + "Student Name: "
                        + tf1.getText()
                        + "\n");
                area2.setText(area2.getText()
                        + "Father's Name: "
                        + tf2.getText()
                        + "\n");
                area2.setText(area2.getText()
                        + "Register No : "
                        + tf3.getText()
                        + "\n");
                area2.setText(area2.getText()
                        + "Email ID: "
                        + tf4.getText()
                        + "\n");
                area2.setText(area2.getText()
                        + "Contact Number: "
                        + tf5.getText()
                        + "\n");
                area2.setText(area2.getText()
                        + "Department Chosen :  "
                        + cb.getSelectedItem()
                        .toString()
                        + "\n");

                if (rb1.isSelected()) {
                    area2.setText(area2.getText()
                            + "Interested to join in: " + " Engineering "
                            + "and Technology\n");
                }
                if (rb2.isSelected()) {
                    area2.setText(area2.getText()
                            + "Interested to join in: "
                            + "Arts and Sciences\n");
                }
                if (rb3.isSelected()) {
                    area2.setText(area2.getText()
                            + "Wants to be a "
                            + "Hosteller \n");
                }
                if (rb4.isSelected()) {
                    area2.setText(area2.getText()
                            + "Wants to be a "
                            + "Day Scholar \n");
                }
                area2.setText(area2.getText()
                        + "Had chosen: "
                        + list1.getSelectedValue()
                        .toString()
                        + "\n");
                area2.setText(area2.getText()
                        + "Had chosen: "
                        + list2.getSelectedValue()
                        .toString()
                        + "\n");

                int index2 = list2.getSelectedIndex();
                area2.setText(area2.getText()+"                             "+" Total amount to be paid "+" will be informed to you using e-mail/post\n ");

                if (e.getSource() == Receipt) {
                    try {
                        FileWriter fw
                                = new FileWriter(
                                "java.txt", true);
                        fw.write(area2.getText());
                        fw.close();
                    }
                    catch (Exception ae) {
                        System.out.println(ae);
                    }
                }

                JOptionPane.showMessageDialog(
                        area2, "Data stored in Server Successfully !");
            };
        });
        addWindowListener(
                new WindowAdapter() {
                    public void windowClosing(
                            WindowEvent we)
                    {
                        System.exit(0);
                    }
                });
        setSize(800, 800);
        setLayout(null);
        setVisible(true);
        setBackground(Color.lightGray);
    }
    public static void main(String[] args)
    {
        new College();
    }
}

Answer 1

Absolute positioning

This:

    l1.setBounds(550, 100, 250, 20);

and lines like it are non-ideal. Absolute positioning will fail to scale the controls and their positions according to different window sizes. Re-think your approach after reading about layouts. Instead of setting bounds, you should specify layouts and border widths, etc.

Members

There is no reason to store these:

JLabel l1, l2, l3, l4,
        l5, l6, l7, l8,
        l9, l10, l12, l13,
        l14, l11, l15;

as members on the class. They should just be declared at the function level. When they go out of scope they will not disappear; the Frame will keep a reference to them but you do not have to.

Variable names

Particularly for important variables like f1 - but probably all of the others, too - you're going to want to give that a more meaningful name, such as fileChooser.

Grouped add

Rather than issuing your adds all in one lump, I think it would be more legible to rearrange these such that they occur directly after the declaration of their respective control, i.e.

        l1 = new JLabel("Fee Report");
        l1.setBounds(550, 100, 250, 20);
        add(l1);

Action listeners

Given the length of your action listener methods, you should move the body of those methods to methods on your class rather than on the anonymous ActionListener object you make.

Answer 2

In addition to the valuable technical hints given by @Reinderien, I'd like to comment on your code structure.

You are doing everything within one class (even inside the constructor of that class):

• Creating the user interface (new JLabel(), setBounds(), add() and so on)
• Getting user interactions (addActionListener())
• Doing the business logic (e.g. generating various reports)
• Presenting results (print(), setText() etc.)

I'd typically expect an application like yours to be split into at least two major parts:

• The business logic, consisting of classes corresponding to the real-world concepts you're working with, e.g. Student, Group, Course, Year. There shouldn't be any user interface elements in there (nothing coming from javax.swing, java.awt, System.out etc.). There you should find the fields that describe a student, a group etc. as well as the actions necessary (e.g. in a class Group a method like add(Student student), modifying the Group's fields to now contain one more Student).

• The user interface, consisting of everything you need to show the user the current state of the application, and to get his commands. Execute them by just calling the business logic.

If you organize your code that way, you gain some benefits:

• Your code is more readable. If you want to know what it means to add a student to a group, you find it in the Group business class. There's no need to skip over the Swing code where get JLabel contents and add text to other JLabels. The same is true for the UI classes. They just define how to interact with the user, e.g. when a user presses this or that button, you want to add a student to a group, no matter how that works internally. That's responsibility of the business logic.
• You gain a better re-usability. Maybe you later want to deploy your app on a server and have the users interact from their browsers. Then you can keep the business logic unchanged, "just" write a fresh web-based front-end, replacing or adding to the Swing user interface.