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java计算算法时间代码,Java计算时间间隔
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JAVA计时算法
你可以在开始和结束的时候，分别记录下当前的时间的这毫秒数。然后再减，以下是一段代码。
public
class
Test{
public
static
void
main(String[]
args)
{
long
startMili=System.currentTimeMillis();//
当前时间对应的毫秒数
System.out.println("开始
"+startMili);
//
执行一段代码,求一百万次随机值
for(int
i=0;i1000000;i++){
Math.random();
}
long
endMili=System.currentTimeMillis();
System.out.println("结束
s"+endMili);
System.out.println("总耗时为："+(endMili-startMili)+"毫秒");
}
}
相关问答
Q1: java计算时间
可以这么写：
public static void compute() {
Scanner scanner = new Scanner(System.in);
int time1, time2, hours, minutes;
time1 = scanner.nextInt();
time2 = scanner.nextInt();
String t1 = String.valueOf(time1);
String t2 = String.valueOf(time2);
//开始时间的小时
int t1_hour = Integer.parseInt(t1.substring(0, t1.length()-2));
//结束时间的小时
int t2_hour = Integer.parseInt(t2.substring(0, t2.length() - 2));
//开始时间的分钟
int t1_minute = Integer.parseInt(t1.substring(t1.length()-2));
//结束时间的分钟
int t2_minute = Integer.parseInt(t2.substring(t2.length() - 2));
//时间差的小时
hours =((t2_hour * 60 + t2_minute)- (t1_hour * 60 + t1_minute))/60;
//时间差的分钟
minutes =((t2_hour * 60 + t2_minute)- (t1_hour * 60 + t1_minute))%60;
System.out.println("The train journey time is "+hours+" hrs "+ minutes+" mins.");
scanner.close();
}
Q2: JAVA 时间计算
如果今天是2011年1月5日，先引入import java.util.Date;import java.text.SimpleDateFormat;
Date time=new Date();
Calendar cal=Calendar.getInstance();
cal.setTime(time);//日历为今天
long tm,tm1;
tm=cal.getTimeInMillis();//得到当前时间与1970年1月1日0点相距的毫秒数
tm1=tm-(24*60*60*1000);//得到昨天与1970年1月1日0点相距的毫秒数
Date time1=new Date(tm1);
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
String tm=sdf.format(time1);//tm就是昨天的日期的字符串表示
Q3: java整么计算时间
提供一个时间操作类给你，你可以调用里面的dateDiff方法，dateDiff（new Date(), getDateFromString("明天的字符串"）表示的就是现在到明天0点之前的差距天数。
你要分钟数的话就自己改一下dateDiff，不要除以60和24就是分钟了
以下是工具类代码
import org.apache.log4j.Logger;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class AdDateUtil {
private static Logger logger = Logger.getLogger(AdDateUtil.class);
static public String getNowStr(String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
String now = sdf.format(new Date());
return now;
}
static public Date getFormatDate(String date, String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
Date d = new Date();
try {
d = sdf.parse(date);
} catch (ParseException e) {
logger.error(e);
}
return d;
}
static public String getDateStr(Date date, String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
String d = sdf.format(date);
return d;
}
static public String getPadZeroString(String s, int size) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i (size - s.length()); i++) {
sb.append("0");
}
sb.append(s);
return sb.toString();
}
/**
* 得到某月的天数
*
* @param year
* @param month
* @return
*/
static public int getDayCountOfMonth(String year, String month) {
Calendar cal = Calendar.getInstance();
// 年
cal.set(Calendar.YEAR, Integer.parseInt(year));
// 月，因为Calendar里的月是从0开始，所以要-1
cal.set(Calendar.MONTH, Integer.parseInt(month) - 1);
return cal.getActualMaximum(Calendar.DAY_OF_MONTH);
}
static public String getYesterday(String format) {
SimpleDateFormat df = new SimpleDateFormat(format);
Calendar now = Calendar.getInstance();
now.roll(Calendar.DAY_OF_YEAR, -1); //昨天
return df.format(now.getTime());
}
/**
* 获取和今天附近的某天
* @param format
* @param diff
* @return
*/
static public String getADay(String format, int diff) {
SimpleDateFormat df = new SimpleDateFormat(format);
Calendar now = Calendar.getInstance();
int beforeM = now.get(Calendar.MONTH);
now.roll(Calendar.DAY_OF_YEAR, diff); //
int nowM = now.get(Calendar.MONTH);
//必须进行日期处理，否则2009-01-04日前七天是2009-12-28
if (nowM beforeM) {
now.roll(Calendar.YEAR, -1);
}
return df.format(now.getTime());
}
static public String getTomorrow(String format) {
SimpleDateFormat df = new SimpleDateFormat(format);
Calendar now = Calendar.getInstance();
now.roll(Calendar.DAY_OF_YEAR, 1); //明天
return df.format(now.getTime());
}
/**
* 得到最近num天的全部日期
* 说明:
* 1.日期是从昨天开始算的.
* 2.如果num=2 , 日期是2008-03-14 ,则返回的结果为 2008-03-12、2008-03-13
* @param num
* @return
*/
public static String[] getDaysByNum(int num, String date) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String[] result = { };
Calendar cal = Calendar.getInstance();
cal.setTime(getDateFromString(date, "yyyy-MM-dd"));
//最近一周
result = new String[num];
for (int i = num; i 0; i--) {
cal.add(Calendar.DAY_OF_YEAR, -1);
result[i - 1] = sdf.format(new Date(cal.getTimeInMillis()));
}
return result;
}
public static Date getDateFromString(String dateStr, String format) {
if ((dateStr == null) || (format == null)) {
try {
throw new Exception("数据类型异常" + dateStr + "|" + format);
} catch (Exception e) {
logger.error("数据类型异常:" + e);
}
}
SimpleDateFormat df = new SimpleDateFormat(format);
Date date;
try {
date = df.parse(dateStr);
return date;
} catch (Exception ex) {
logger.error(ex);
return new Date();
}
}
static public int getNowYear() {
Calendar cal = Calendar.getInstance();
return cal.get(Calendar.YEAR);
}
static public int getNowMonth() {
Calendar cal = Calendar.getInstance();
return cal.get(Calendar.MONTH) + 1;
}
public static String[] getMonthRang(String year, String month) {
String beginDate = year + "-" + month + "-01";
String endDate = year + "-" + month + "-" +
getDayCountOfMonth(year, month);
return getDaysByRang(beginDate, endDate);
}
public static String[] getDaysByRang(String beginDate, String endDate) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
//得到两个日期间相差多少天
int num = dateDiff(beginDate, endDate);
if (num 0) {
//颠倒一下日期
String tmp = beginDate;
beginDate = endDate;
endDate = tmp;
num = 0 - num;
}
String[] result = { };
Calendar cal = Calendar.getInstance();
try {
cal.setTime(sdf.parse(beginDate));
} catch (ParseException e) {
e.printStackTrace();
}
num = num + 1; //把开始和结束日期都包含进去
result = new String[num];
for (int i = 0; i num; i++) {
if (i 0) {
cal.add(Calendar.DAY_OF_YEAR, 1);
}
result[i] = sdf.format(new Date(cal.getTimeInMillis()));
}
return result;
}
public static int dateDiff(String beginDate, String endDate) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date date = null;
try {
date = sdf.parse(endDate);
} catch (ParseException e) {
date = new Date();
e.printStackTrace();
}
long end = date.getTime();
try {
date = sdf.parse(beginDate);
} catch (ParseException e) {
date = new Date();
e.printStackTrace();
}
long begin = date.getTime();
long day = (end - begin) / (1000 * 3600 * 24); //除1000是把毫秒变成秒
return Integer.parseInt(Long.toString(day));
}
public static void main(String[] args) {
System.out.println(AdDateUtil.getADay("yyyy-MM-dd", -7));
}
}
