怎么用Java实现精确到毫秒的倒计时器
现在要用Java实现一个倒计时器,我采用的办法是:先获得总的毫秒数matchTime,然后用Timer,每隔一毫秒就让matchTime减1,然后再把matchTime转换成时间的格式。但是这样做出来的时间走的比现实时间要慢得多,如果改成每100秒减100次,就和现实时间差不多了,这也就是说精确到了0.1秒。但是有没有办法精确到毫秒呢?
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看起来是timer的精度不够
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getMilliseconds(),返回毫秒数。
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System.nanoTime()
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windows系统的计时精确度在15毫秒左右。
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import java.util.Date;import java.io.PrintWriter;import java.io.StringWriter;import java.awt.Font;import java.awt.BorderLayout;import java.awt.event.MouseEvent;import java.awt.event.MouseAdapter;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.SwingConstants;/** * TimerFrame - 倒计时窗口 * @author SageZk * @version 1.0 */@SuppressWarnings("serial")public class TimerFrame extends JFrame { private long time = (long) (1.2 * 60 * 1000L); //倒计时时间(单位毫秒) private JLabel lblTime; private Thread runner; public TimerFrame() { super("TimerFrame"); this.lblTime = new JLabel("单击开始"); this.lblTime.setFont(new Font("Monospaced", Font.BOLD, 60)); this.lblTime.setHorizontalAlignment(SwingConstants.CENTER); this.lblTime.addMouseListener(new MouseAdapter() { public void mouseClicked(MouseEvent e) { if (runner != null) runner.start(); } }); this.runner = new Thread(new Runnable() { public void run() { Date t = new Date(); StringWriter sw = new StringWriter(); StringBuffer sb = sw.getBuffer(); PrintWriter pw = new PrintWriter(sw); long cur = 0L, end = System.currentTimeMillis() + time; while ((cur = end - System.currentTimeMillis()) > 0) { t.setTime(cur); pw.format("%1$tM:%1$tS.%tL", t); pw.flush(); lblTime.setText(sb.toString()); sb.setLength(0); try { Thread.sleep(6L); } catch (InterruptedException e) { } } lblTime.setText("00:00.000"); try { Thread.sleep(1200L); } catch (InterruptedException e) { } lblTime.setText("Bomb!!!"); } }); this.runner.setDaemon(true); getContentPane().add(this.lblTime, BorderLayout.CENTER); setResizable(false); setBounds(0, 0, 460, 330); setLocationRelativeTo(null); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } public static void main(String[] args) { new TimerFrame().setVisible(true); }}
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顶楼上的.
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import java.util.Date;
import java.io.PrintWriter;
import java.awt.Font;
import java.swing.JFrame;
public TimerFrame() {
super("TimerFrame");
this.lblTime = new JLabel("单击开始");
this.lblTime.setFont(new Font("Monospaced", Font.BOLD, 60));
this.lblTime.setHorizontalAlignment(SwingConstants.CENTER);
this.lblTime.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if (runner != null) runner.start();
}
});
this.runner = new Thread(new Runnable() {
public void run() {
Date t = new Date();
StringWriter sw = new StringWriter();
StringBuffer sb = sw.getBuffer();
PrintWriter pw = new PrintWriter(sw);
long cur = 0L, end = System.currentTimeMillis() + time;
while ((cur = end - System.currentTimeMillis()) > 0) {
t.setTime(cur);
pw.format("%1$tM:%1$tS.%tL", t);
pw.flush();
lblTime.setText(sb.toString());
sb.setLength(0);
try {
Thread.sleep(6L);
} catch (InterruptedException e) {
}
}
lblTime.setText("00:00.000");
try {
Thread.sleep(1200L);
} catch (InterruptedException e) {
}
lblTime.setText("Bomb!!!");
}
});
this.runner.setDaemon(true);
getContentPane().add(this.lblTime, BorderLayout.CENTER);
setResizable(false);
setBounds(0, 0, 460, 330);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new TimerFrame().setVisible(true);
}
}
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8楼的 Copy 我代码也不贴全,你那能通过编译吗?
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用Timer 不就行了,quartz 也可以。
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看见线程我就头疼
怎么学那玩意?
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this.runner = new Thread(new Runnable() {
public void run() {
Date t = new Date();
StringWriter sw = new StringWriter();
StringBuffer sb = sw.getBuffer();
PrintWriter pw = new PrintWriter(sw);
long cur = 0L, end = System.currentTimeMillis() + time;
while ((cur = end - System.currentTimeMillis()) > 0) {
t.setTime(cur);
pw.format("%1$tM:%1$tS.%tL", t);
pw.flush();
lblTime.setText(sb.toString());
sb.setLength(0);
try {
Thread.sleep(6L);
} catch (InterruptedException e) {
}
}
lblTime.setText("00:00.000");
try {
Thread.sleep(1200L);
} catch (InterruptedException e) {
}
lblTime.setText("Bomb!!!");
}
});
this.runner.setDaemon(true);
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估计毫秒级,应该不好实现。我的机器,所有线程轮一圈,大概10毫秒。
所以,一旦程序中出现sleep,那么下次执行的毫秒数很有可能会滞后(每次最多10毫秒)。
JDK1.5当中的Timer类。楼主可以去看看。如果应用简单的话。应该能够达到要求。