How to make Timer countdown along with progress ba

How can I make it so that the progress bar slowly goes down with the time limit?

class GamePanel extends JPanel implements MouseListener, ActionListener
{
    private JButton quit;
    private JButton q;
    private Font loadFont;

    public GamePanel()
    {
        setBackground(Color.blue); // sets background color
        this.setLayout(null);
        quit = new JButton("Quit");
        quit.addActionListener(this);
        quit.setBounds(550, 700, 100, 30);
        this.add(quit);

        q = new JButton("Questions");
        q.addActionListener(this);
        q.setBounds(100, 100, 120, 30);
        this.add(q);

        loadFont = new Font("Serif", Font.PLAIN, 30);
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g.setColor(Color.black);
        g.fillRect(80, 100, 610, 560);
        g.setColor(Color.white);
        g.fillRect(90, 110, 110, 100);// 1st column
        g.fillRect(90, 220, 110, 100);//
        g.fillRect(90, 330, 110, 100);//
        g.fillRect(90, 440, 110, 100);//
        g.fillRect(90, 550, 110, 100);//
        g.fillRect(210, 110, 110, 100);// 2nd column
        g.fillRect(210, 220, 110, 100);//
        g.fillRect(210, 330, 110, 100);//
        g.fillRect(210, 440, 110, 100);//
        g.fillRect(210, 550, 110, 100);//
        g.fillRect(330, 110, 110, 100);// 3rd column
        g.fillRect(330, 220, 110, 100);//
        g.fillRect(330, 330, 110, 100);//
        g.fillRect(330, 440, 110, 100);//
        g.fillRect(330, 550, 110, 100);//
        g.fillRect(450, 110, 110, 100);// 4th column
        g.fillRect(450, 220, 110, 100);//
        g.fillRect(450, 330, 110, 100);//
        g.fillRect(450, 440, 110, 100);//
        g.fillRect(450, 550, 110, 100);//
        g.fillRect(570, 110, 110, 100);// 5th column
        g.fillRect(570, 220, 110, 100);//
        g.fillRect(570, 330, 110, 100);//
        g.fillRect(570, 440, 110, 100);//
        g.fillRect(570, 550, 110, 100);//
        g.setColor(Color.green);
        g.setFont(loadFont);
        g.drawString(input + ":", 100, 710);
    }

    public void actionPerformed(ActionEvent e)
    {
        String order = e.getActionCommand();
        if(order.equals("Quit"))
            cards.show(c, "Introduction");
        if(order.equals("Questions"))
            cards.show(c, "Questions");
    }

    public void mousePressed(MouseEvent e) {}
    public void mouseReleased(MouseEvent e) {}
    public void mouseClicked(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}
}

class QuestionPanel extends JPanel implements ActionListener
{
    private long startTime, elapsedTime;
    private Timer timer;
    private int countdown;
    private Font loadFont;

    public QuestionPanel()
    {
        setBackground(Color.pink); // sets background color
        this.setLayout(null);  // moved into constructor from ActionPerformed: only change layout in constructor
        startTime = 0;
        elapsedTime = 0;
        countdown = 590;
        loadFont = new Font("Segoe Script", Font.BOLD, 20);
        if(timer == null)
        {// use the biggest value possible that provides your desired time keeping precision (usually no less than 15 on Windows)
            timer = new Timer(100, this);  
            startTime = System.currentTimeMillis();  // gets start time in milliseconds
            timer.start();
        }
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g.fillRect(100, 100, 600, 25);
        g.setColor(Color.green);
        g.fillRect(105, 105, countdown, 15);
        g.setColor(Color.black);
        g.setFont(loadFont);
        g.drawString("" + ((System.currentTimeMillis() - startTime) / 1000.0), 100, 80);  // display remaining time
    }

    public void actionPerformed(ActionEvent e)
    {
        String command = e.getActionCommand();
        elapsedTime = System.currentTimeMillis() - startTime;
        if(elapsedTime < (5000))
        {
            countdown--;
            repaint();
        }
        else
        {
            timer.stop();
            if(timer == null)
            {
                timer = new Timer(500, this);
                timer.start();
            }
        }
        if(elapsedTime >= (5000))  // can't use == here because of limited precision of system clock
            cards.show(c, "Correct!");
    }
}

class AnswerPanel extends JPanel implements ActionListener
{
    private JButton revert;

    public AnswerPanel()
    {
        setBackground(Color.yellow); // sets background color
        this.setLayout(null);
        revert = new JButton("Back");
        revert.addActionListener(this);
        revert.setBounds(340, 700, 100, 30);
        this.add(revert);
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
    }

    public void actionPerformed(ActionEvent e)
    {
        String directive = e.getActionCommand();
        if(directive.equals("Back"))
            cards.show(c, "Start");
    }
}

class FailPanel extends JPanel implements ActionListener
{
    private JButton turnaround;

    public FailPanel()
    {
        setBackground(Color.green); // sets background color
        this.setLayout(null);
        turnaround = new JButton("Back");
        turnaround.addActionListener(this);
        turnaround.setBounds(340, 700, 100, 30);
        this.add(turnaround);
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
    }

    public void actionPerformed(ActionEvent e)
    {
        String bidding = e.getActionCommand();
        if(bidding.equals("Back"))
            cards.show(c, "Start");
    }
}
}// end of the entire program

回答1:

Sorry, I still could not find the motivation to actually read your code, but just threw together this example based on the question. See if it gives you some ideas.

Note that it is an SSCCE and uses just 40 lines of code in all.

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

class CountDownProgressBar {

    Timer timer;
    JProgressBar progressBar;

    CountDownProgressBar() {
        progressBar = new JProgressBar(JProgressBar.VERTICAL, 0, 10);
        progressBar.setValue(10);
        ActionListener listener = new ActionListener() {
            int counter = 10;
            public void actionPerformed(ActionEvent ae) {
                counter--;
                progressBar.setValue(counter);
                if (counter<1) {
                    JOptionPane.showMessageDialog(null, "Kaboom!");
                    timer.stop();
                } 
            }
        };
        timer = new Timer(1000, listener);
        timer.start();
        JOptionPane.showMessageDialog(null, progressBar);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater( new Runnable() {
            public void run() {
                CountDownProgressBar cdpb = new CountDownProgressBar();
            }
        });
    }
}

回答2:

From the looks of it, all of this code is within a big Java file? That is a bad idea.

You should have a good reason to define a class as an inner class, and from the looks of it, you do not have one for QuestionPanel and others.

As for the problem, your paintComponent method is called every time your counter is updated, which is right now roughly once every 0.1 seconds, yet you only tick by 1 pixel on each update, so by the end of 5 seconds, you've cut off 10*5 pixels (50). What you should do is update the progress bar by a different mechanism, such as a calculating the current time processed:

long processed = System.currentTimeMillis() - startTime;
double percent = Math.max(0, 1 - processed / 5000.0);
int width = (int)(590 * percent);

回答3:

That is definitely too much information, and a very broad question. I'd say at most you only need to include the code for the class where the timer is, and the class where the progress bar gets drawn.

From skimming the code, I'm guessing you're using a rectangle to draw the progress bar. Based on that, one way you could go about it would be using a variable to store the width of the bar, and every time the timer ticks, decrease the width of the bar by a set amount. Then just set the width of the rectangle drawn to the value stored in the variable.