This one gets asked alot, so I thought I’d post it seperately.
Attributions:
Contributed to the community by TheLorax.
This version from mbishop’s pacman clone.
// SleepTimer.java
// Here we have "thelorax"'s famous "sleep" timer. This uses Thread.sleep()
// to get higher-resolution timing under Windows 9x platforms.
public class SleepTimer implements Runnable {
// Number of elapsed ticks. A tick is fired every time a sleep occurs.
private int ticks;
// The Thread that will be run.
private Thread timerThread;
// Our current delay and our desired delay.
private long msDelay, targetMs;
// Do we let this Thread correct itself?
private boolean autoCorrection = true;
// Is this Thread running?
private boolean running = false;
// Difference since last tick.
private long timeDiff;
// Desired frames per second.
private int autoLength;
// Start time and end time.
private long startTime, endTime;
// Of course we want a high priority to do our timing right.
public SleepTimer() {
timerThread = new Thread(this);
timerThread.setPriority(Thread.MAX_PRIORITY);
timerThread.setDaemon(true);
}
public int getTickCount() {
return ticks;
}
// I added this so I could see the number of ticks missed
// on a per-second basis.
public void resetTickCount() {
ticks = 0;
}
public void startTimer() {
running = true;
timerThread.start();
}
public void stopTimer() {
running = false;
try {
timerThread.join();
}
catch (Exception e) {}
}
// We set auto-correction with a desired frames (ticks) per second.
public void setAutoCorrection(boolean on, int sampleLength) {
autoCorrection = on;
autoLength = sampleLength;
}
public void setDelay(int tmsDelay) {
msDelay = tmsDelay;
targetMs = msDelay;
}
// Sleeps the specified amount, lets other Threads know, then
// corrects itself if auto-correcting is set.
public void run() {
startTime = System.currentTimeMillis();
try {
while (running) {
Thread.sleep(msDelay);
ticks++;
synchronized(this) {
notifyAll();
}
if (autoCorrection && (ticks % autoLength == 0)) {
endTime = System.currentTimeMillis();
timeDiff = ((endTime - startTime) / autoLength) - targetMs;
startTime = endTime;
if (timeDiff > 0) {
msDelay--;
}
if (timeDiff < 0) {
msDelay++;
}
}
}
}
catch (Exception e) {
System.err.println("Exception in Timer Thread.");
e.printStackTrace();
}
}
}
