Build a Java Exam App: Step‑by‑Step Swing Implementation

Project Background

With the rise of mobile internet, online exams offer many advantages over traditional paper tests, such as reduced time, labor, and cost, as well as improved objectivity and fairness. Leveraging existing computer hardware, software, and network resources enables paper‑less examinations.

Project Goals

Design an application that displays driving‑license theory questions, includes a timer, evaluates user answers upon submission, calculates the score, and presents the exam result.

Implementation

First, review the previous simple Java exam system (part one) to complete the window, questions, options, progress display, buttons, timer, total score, and emoticon display. The initial UI looks like the image below.

Next, complete the remaining features as follows.

(1) Show background image and design the UI

Set component opacity:

buttona.setOpaque(false);
buttonb.setOpaque(false);
buttonc.setOpaque(false);
buttond.setOpaque(false);
panel01.setOpaque(false);
panel02.setOpaque(false);
panel03.setOpaque(false);
panel04.setOpaque(false);

Set bounds for the background label:

label.setBounds(0, 0, bg.getIconWidth(), bg.getIconHeight());

Convert the content pane to a panel:

imagePanel = (JPanel) this.getContentPane();
imagePanel.setOpaque(false);

Add the background label to the lowest layer of the layered pane:

this.getLayeredPane().add(label, new Integer(Integer.MIN_VALUE));

(2) Add listeners to components

btn_last.addActionListener(ml);
btn_next.addActionListener(ml);
btn_finish.addActionListener(ml);
buttona.addActionListener(ml);
buttonb.addActionListener(ml);
buttonc.addActionListener(ml);
buttond.addActionListener(ml);

(3) Create and start the timer

timer = new Timer(1000, new TimerListener());
timer.start();

(4) Event handling

Red button = unanswered, green button = answered.

public class MyListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
        for (int i = 0; i < 5; i++) {
            if (e.getSource() == btn_index[i]) { // buttons 1‑5
                num = i; // update current question index
                showItem(num);
                showMychoice(num);
                showButton(num);
            }
        }
    }
}

Previous question:

if (e.getSource() == btn_last) {
    if (num > 0) {
        num--;
    }
    showItem(num);
    showMychoice(num);
    showButton(num);
}

Next question:

if (e.getSource() == btn_next) {
    if (num < str_problem.length - 1) {
        num++;
    }
    showItem(num);
    showMychoice(num);
    showButton(num);
}

Single‑choice handling:

if (e.getSource() == buttona) { my_answer[num] = 1; btn_index[num].setBackground(Color.GREEN); }
if (e.getSource() == buttonb) { my_answer[num] = 2; btn_index[num].setBackground(Color.GREEN); }
if (e.getSource() == buttonc) { my_answer[num] = 3; btn_index[num].setBackground(Color.GREEN); }
if (e.getSource() == buttond) { my_answer[num] = 4; btn_index[num].setBackground(Color.GREEN); }

Submit exam and stop timer:

if (e.getSource() == btn_finish) {
    timer.stop();
    TextFinish();
}

(5) Helper methods

public void showItem(int i) {
    problem.setText(str_problem[i]);
    buttona.setText(answer_a[i]);
    buttonb.setText(answer_b[i]);
    buttonc.setText(answer_c[i]);
    buttond.setText(answer_d[i]);
    group.clearSelection();
}

public void showMychoice(int i) {
    switch (my_answer[i]) {
        case 1: buttona.setSelected(true); break;
        case 2: buttonb.setSelected(true); break;
        case 3: buttonc.setSelected(true); break;
        case 4: buttond.setSelected(true); break;
    }
}

public void showButton(int i) {
    if (i == 0) {
        btn_last.setEnabled(false);
        btn_next.setEnabled(true);
    } else if (i == str_problem.length - 1) {
        btn_last.setEnabled(true);
        btn_next.setEnabled(false);
    } else {
        btn_last.setEnabled(true);
        btn_next.setEnabled(true);
    }
}

public void TextFinish() {
    btn_last.setEnabled(false);
    btn_next.setEnabled(false);
    btn_finish.setEnabled(false);
    buttona.setEnabled(false);
    buttonb.setEnabled(false);
    buttonc.setEnabled(false);
    buttond.setEnabled(false);
}

for (int i = 0; i < 4; i++) {
    btn_index[i].setEnabled(false);
    if (my_answer[i] == right[i]) {
        score = score + 20;
    }
}

label_score.setText("Total Score:" + score);
if (score == 100) {
    image.setIcon(new ImageIcon("image//lauge.jpg"));
} else {
    image.setIcon(new ImageIcon("image//cry.jpg"));
}

(6) Timer for automatic submission

public class TimerListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
        second--;
        if (second < 0) {
            minute--;
            second = 59;
        }
        label_time.setText(minute + ":" + second);
        if (minute == 0 && second == 0) {
            timer.stop();
            label_time.setText("Exam Over!");
            TextFinish();
        }
    }
}

Conclusion

1. Demonstrated basic usage of JLabel, JButton, JPanel, ButtonGroup, and JRadioButton components and their event handling to build the UI.

2. Added event‑handling functions; the main difficulty lies in understanding constructors and inner‑class creation. The code is straightforward and serves as a simple example.

3. To obtain the full project code, reply with the keyword “考试系统” in the backend.