我是编程的初学者（学生）并被指派创建游戏。 我正在制作的游戏叫做boggle。 其中玩家必须在给定时间内在随机字母板中找到单词。 但我在创建计时器时遇到了麻烦。 这就是我的计时器应该做的事情：
我需要知道的是如何让它倒计时。 我不认为我需要一个ActionListener，因为它在创建类的那一刻开始滴答作响。
任何帮助，建议，链接，向正确的方向推进都将被张开双臂接受。
答案 0 :(得分：33)
import java.util.Scanner;
import java.util.Timer;
import java.util.TimerTask;
public class Stopwatch {
static int interval;
static Timer timer;
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("Input seconds => : ");
String secs = sc.nextLine();
int delay = 1000;
int period = 1000;
timer = new Timer();
interval = Integer.parseInt(secs);
System.out.println(secs);
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
System.out.println(setInterval());
}
}, delay, period);
}
private static final int setInterval() {
if (interval == 1)
timer.cancel();
return --interval;
}
}
试试这个。
答案 1 :(得分：9)
您会看到有人使用Timer类来执行此操作。不幸的是，它并不总是准确的。最好的办法是在用户输入输入时获取系统时间，计算目标系统时间，并检查系统时间是否超过目标系统时间。如果有，那就打破循环。
答案 2 :(得分：3)
您可以使用applet创建倒数计时器，下面是代码，
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.Timer; // not java.util.Timer
import java.text.NumberFormat;
import java.net.*;
/**
* An applet that counts down from a specified time. When it reaches 00:00,
* it optionally plays a sound and optionally moves the browser to a new page.
* Place the mouse over the applet to pause the count; move it off to resume.
* This class demonstrates most applet methods and features.
**/
public class Countdown extends JApplet implements ActionListener, MouseListener
{
long remaining; // How many milliseconds remain in the countdown.
long lastUpdate; // When count was last updated
JLabel label; // Displays the count
Timer timer; // Updates the count every second
NumberFormat format; // Format minutes:seconds with leading zeros
Image image; // Image to display along with the time
AudioClip sound; // Sound to play when we reach 00:00
// Called when the applet is first loaded
public void init() {
// Figure out how long to count for by reading the "minutes" parameter
// defined in a <param> tag inside the <applet> tag. Convert to ms.
String minutes = getParameter("minutes");
if (minutes != null) remaining = Integer.parseInt(minutes) * 60000;
else remaining = 600000; // 10 minutes by default
// Create a JLabel to display remaining time, and set some properties.
label = new JLabel();
label.setHorizontalAlignment(SwingConstants.CENTER );
label.setOpaque(true); // So label draws the background color
// Read some parameters for this JLabel object
String font = getParameter("font");
String foreground = getParameter("foreground");
String background = getParameter("background");
String imageURL = getParameter("image");
// Set label properties based on those parameters
if (font != null) label.setFont(Font.decode(font));
if (foreground != null) label.setForeground(Color.decode(foreground));
if (background != null) label.setBackground(Color.decode(background));
if (imageURL != null) {
// Load the image, and save it so we can release it later
image = getImage(getDocumentBase(), imageURL);
// Now display the image in the JLabel.
label.setIcon(new ImageIcon(image));
}
// Now add the label to the applet. Like JFrame and JDialog, JApplet
// has a content pane that you add children to
getContentPane().add(label, BorderLayout.CENTER);
// Get an optional AudioClip to play when the count expires
String soundURL = getParameter("sound");
if (soundURL != null) sound=getAudioClip(getDocumentBase(), soundURL);
// Obtain a NumberFormat object to convert number of minutes and
// seconds to strings. Set it up to produce a leading 0 if necessary
format = NumberFormat.getNumberInstance();
format.setMinimumIntegerDigits(2); // pad with 0 if necessary
// Specify a MouseListener to handle mouse events in the applet.
// Note that the applet implements this interface itself
addMouseListener(this);
// Create a timer to call the actionPerformed() method immediately,
// and then every 1000 milliseconds. Note we don't start the timer yet.
timer = new Timer(1000, this);
timer.setInitialDelay(0); // First timer is immediate.
}
// Free up any resources we hold; called when the applet is done
public void destroy() { if (image != null) image.flush(); }
// The browser calls this to start the applet running
// The resume() method is defined below.
public void start() { resume(); } // Start displaying updates
// The browser calls this to stop the applet. It may be restarted later.
// The pause() method is defined below
public void stop() { pause(); } // Stop displaying updates
// Return information about the applet
public String getAppletInfo() {
return "Countdown applet Copyright (c) 2003 by David Flanagan";
}
// Return information about the applet parameters
public String[][] getParameterInfo() { return parameterInfo; }
// This is the parameter information. One array of strings for each
// parameter. The elements are parameter name, type, and description.
static String[][] parameterInfo = {
{"minutes", "number", "time, in minutes, to countdown from"},
{"font", "font", "optional font for the time display"},
{"foreground", "color", "optional foreground color for the time"},
{"background", "color", "optional background color"},
{"image", "image URL", "optional image to display next to countdown"},
{"sound", "sound URL", "optional sound to play when we reach 00:00"},
{"newpage", "document URL", "URL to load when timer expires"},
};
// Start or resume the countdown
void resume() {
// Restore the time we're counting down from and restart the timer.
lastUpdate = System.currentTimeMillis();
timer.start(); // Start the timer
}
// Pause the countdown
void pause() {
// Subtract elapsed time from the remaining time and stop timing
long now = System.currentTimeMillis();
remaining -= (now - lastUpdate);
timer.stop(); // Stop the timer
}
// Update the displayed time. This method is called from actionPerformed()
// which is itself invoked by the timer.
void updateDisplay() {
long now = System.currentTimeMillis(); // current time in ms
long elapsed = now - lastUpdate; // ms elapsed since last update
remaining -= elapsed; // adjust remaining time
lastUpdate = now; // remember this update time
// Convert remaining milliseconds to mm:ss format and display
if (remaining < 0) remaining = 0;
int minutes = (int)(remaining/60000);
int seconds = (int)((remaining)/1000);
label.setText(format.format(minutes) + ":" + format.format(seconds));
// If we've completed the countdown beep and display new page
if (remaining == 0) {
// Stop updating now.
timer.stop();
// If we have an alarm sound clip, play it now.
if (sound != null) sound.play();
// If there is a newpage URL specified, make the browser
// load that page now.
String newpage = getParameter("newpage");
if (newpage != null) {
try {
URL url = new URL(getDocumentBase(), newpage);
getAppletContext().showDocument(url);
}
catch(MalformedURLException ex) { showStatus(ex.toString()); }
}
}
}
// This method implements the ActionListener interface.
// It is invoked once a second by the Timer object
// and updates the JLabel to display minutes and seconds remaining.
public void actionPerformed(ActionEvent e) { updateDisplay(); }
// The methods below implement the MouseListener interface. We use
// two of them to pause the countdown when the mouse hovers over the timer.
// Note that we also display a message in the statusline
public void mouseEntered(MouseEvent e) {
pause(); // pause countdown
showStatus("Paused"); // display statusline message
}
public void mouseExited(MouseEvent e) {
resume(); // resume countdown
showStatus(""); // clear statusline
}
// These MouseListener methods are unused.
public void mouseClicked(MouseEvent e) {}
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
}