package canghailan.util;
import java.util.concurrent.TimeUnit;
/**
* User: canghailan
* Date: 11-12-9
* Time: 下午3:45
* <pre>
* RUNNING:
* startTime split now
* |<- getSplitTime() ->|<- getTimeFromSplit() ->|
* |<- getTime() ->|
* <pre/>
* <pre>
* STOPPED:
* startTime stop now
* |<- getTime() ->|
* <pre/>
*/
public class StopWatch {
private long startTime;
private long stopTime;
private State state;
private boolean split;
public StopWatch() {
reset();
}
public void start() {
if (state == State.UNSTARTED) {
startTime = System.nanoTime();
state = State.RUNNING;
return;
}
throw new RuntimeException("Stopwatch already started or stopped.");
}
public void stop() {
switch (state) {
case RUNNING: {
stopTime = System.nanoTime();
}
case SUSPENDED: {
state = State.STOPPED;
split = false;
return;
}
}
throw new RuntimeException("Stopwatch is not running.");
}
public void reset() {
state = State.UNSTARTED;
split = false;
}
public void split() {
if (state == State.RUNNING) {
stopTime = System.nanoTime();
split = true;
return;
}
throw new RuntimeException("Stopwatch is not running.");
}
public void suspend() {
if (state == State.RUNNING) {
stopTime = System.nanoTime();
state = State.SUSPENDED;
return;
}
throw new RuntimeException("Stopwatch must be running to suspend.");
}
public void resume() {
if (state == State.SUSPENDED) {
startTime += System.nanoTime() - stopTime;
state = State.RUNNING;
return;
}
throw new RuntimeException("Stopwatch must be suspended to resume.");
}
public long getTime() {
return TimeUnit.NANOSECONDS.toMillis(getNanoTime());
}
public long getNanoTime() {
switch (state) {
case RUNNING: {
return System.nanoTime() - startTime;
}
case STOPPED:
case SUSPENDED: {
return stopTime - startTime;
}
case UNSTARTED: {
return 0;
}
}
throw new RuntimeException("Should never get here.");
}
public long getSplitTime() {
return TimeUnit.NANOSECONDS.toMillis(getSplitNanoTime());
}
public long getSplitNanoTime() {
if (split) {
return stopTime - startTime;
}
throw new RuntimeException("Stopwatch must be running and split to get the split time.");
}
public long getTimeFromSplit() {
return TimeUnit.NANOSECONDS.toMillis(getNanoTimeFromSplit());
}
public long getNanoTimeFromSplit() {
if (state == State.RUNNING && split) {
return System.nanoTime() - stopTime;
}
throw new RuntimeException("Stopwatch must be running and split to get the time from split.");
}
enum State {
UNSTARTED,
RUNNING,
STOPPED,
SUSPENDED
}
}