我怎样才能使进度条慢慢降低时间限制？
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
答案 0 :(得分：11)
抱歉，我仍然找不到实际阅读代码的动机，但只是根据问题将这个例子汇总在一起。看看它是否给你一些想法。
请注意，它是一个SSCCE，并且只使用了40行代码。
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();
}
});
}
}
答案 1 :(得分：4)
从它的外观来看，所有这些代码都在一个大的Java文件中？这是个坏主意。
你应该有充分的理由将一个类定义为一个内部类，从它的外观来看，你没有一个用于QuestionPanel和其他类。
至于问题，每次更新计数器时都会调用paintComponent方法，现在大约每0.1秒调用一次，但每次更新时只需按1个像素，所以到最后5秒，你已经切断了10 * 5像素（50）。您应该做的是通过不同的机制更新进度条，例如计算当前处理的时间：
long processed = System.currentTimeMillis() - startTime;
double percent = Math.max(0, 1 - processed / 5000.0);
int width = (int)(590 * percent);
答案 2 :(得分：2)
这绝对是太多的信息，而且是一个非常广泛的问题。我要说的最多只需要包含定时器所在类的代码，以及绘制进度条的类。
从略读代码，我猜你正在使用矩形来绘制进度条。基于此，您可以采用的一种方法是使用变量来存储条的宽度，并且每次计时器滴答时，将条的宽度减小一定量。然后只需将绘制的矩形的宽度设置为存储在变量中的值。