使用StopWatch类来计时

package com.generationjava.test;
/**
* 在调试或者测试情形下需要计时非常有用
*/
public class StopWatch {
static public int AN_HOUR = 60 * 60 * 1000;
static public int A_MINUTE = 60 * 1000;
private long startTime = -1;
private long stopTime = -1;
/**
* 启动秒表
*/
public void start() {
this.startTime =System.currentTimeMillis();
}
/**
* 停止秒表
*/
public void stop() {
this.stopTime =System.currentTimeMillis();
}
/**
* 重置秒表
*/
public void reset() {
this.startTime = -1;
this.stopTime = -1;
}
/**
* 分割时间
*/
public void split() {
this.stopTime =System.currentTimeMillis();
}
/**
* 移除分割
*/
public void unsplit() {
this.stopTime = -1;
}
/**
* 获得秒表的时间，这个时间或者是启动时和最后一个分割时刻的时间差，
* 或者是启动时和停止时的时间差，或者是启动时和这个方法被调用时的差
*/
public long getTime() {
if(stopTime != -1) {
return(System.currentTimeMillis() - this.startTime);
} else {
return this.stopTime - this.startTime;
}
}
public String toString() {
return getTimeString();
}
/**
* 取得String类型的时间差
* 形式为小时，分钟，秒和毫秒
*/
public String getTimeString() {
int hours, minutes, seconds,milliseconds;
long time = getTime();
hours = (int) (time / AN_HOUR);
time = time - (hours *AN_HOUR);
minutes = (int) (time /A_MINUTE);
time = time - (minutes *A_MINUTE);
seconds = (int) (time / 1000);
time = time - (seconds * 1000);
milliseconds = (int) time;
return hours + "h:" +minutes + "m:"
+ seconds + "s:" + milliseconds +
}