【发布时间】：2012-03-28 14:13:58
【问题描述】：
我想找到给定月份的所有周六和周日。我该怎么做？
【问题讨论】：
标签： java android date calendar
【发布时间】：2012-03-28 14:13:58
【问题描述】：
java.util 日期时间 API 及其格式化 API SimpleDateFormat 已过时且容易出错。建议完全停止使用，改用modern Date-Time API*。
另外，下面引用的是Home Page of Joda-Time的通知：
请注意，从 Java SE 8 开始，用户被要求迁移到 java.time (JSR-310) - JDK 的核心部分，它取代了这个项目。
使用现代日期时间 API java.time 的解决方案：
import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.YearMonth;
import java.time.temporal.TemporalAdjusters;
import java.util.List;
import java.util.stream.Collectors;
public class Main {
public static void main(String[] args) {
// Test
System.out.println(getWeekends(2));// All weekends of Feb in the current year
System.out.println(getWeekends(2020, 2));// All weekends of Feb 2020
}
/*
* All weekends (Sat & Sun) of the given month in the current year
*/
static List<LocalDate> getWeekends(int month) {
LocalDate firstDateOfTheMonth = LocalDate.now().withMonth(month).with(TemporalAdjusters.firstDayOfMonth());
return firstDateOfTheMonth
.datesUntil(firstDateOfTheMonth.plusMonths(1))
.filter(date -> date.getDayOfWeek() == DayOfWeek.SATURDAY || date.getDayOfWeek() == DayOfWeek.SUNDAY)
.collect(Collectors.toList());
}
/*
* All weekends (Sat & Sun) of the given year and the month
*/
static List<LocalDate> getWeekends(int year, int month) {
LocalDate firstDateOfTheMonth = YearMonth.of(year, month).atDay(1);
return firstDateOfTheMonth
.datesUntil(firstDateOfTheMonth.plusMonths(1))
.filter(date -> date.getDayOfWeek() == DayOfWeek.SATURDAY || date.getDayOfWeek() == DayOfWeek.SUNDAY)
.collect(Collectors.toList());
}
}
输出：
[2021-02-06, 2021-02-07, 2021-02-13, 2021-02-14, 2021-02-20, 2021-02-21, 2021-02-27, 2021-02-28]
[2020-02-01, 2020-02-02, 2020-02-08, 2020-02-09, 2020-02-15, 2020-02-16, 2020-02-22, 2020-02-23, 2020-02-29]
非Stream解决方案：
import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.YearMonth;
import java.time.temporal.TemporalAdjusters;
import java.util.ArrayList;
import java.util.List;
public class Main {
public static void main(String[] args) {
// Test
System.out.println(getWeekends(2));// All weekends of Feb in the current year
System.out.println(getWeekends(2020, 2));// All weekends of Feb 2020
}
/*
* All weekends (Sat & Sun) of the given month in the current year
*/
static List<LocalDate> getWeekends(int month) {
LocalDate firstDateOfTheMonth = LocalDate.now().withMonth(month).with(TemporalAdjusters.firstDayOfMonth());
List<LocalDate> list = new ArrayList<>();
for (LocalDate date = firstDateOfTheMonth; !date
.isAfter(firstDateOfTheMonth.with(TemporalAdjusters.lastDayOfMonth())); date = date.plusDays(1))
if (date.getDayOfWeek() == DayOfWeek.SATURDAY || date.getDayOfWeek() == DayOfWeek.SUNDAY)
list.add(date);
return list;
}
/*
* All weekends (Sat & Sun) of the given year and the month
*/
static List<LocalDate> getWeekends(int year, int month) {
LocalDate firstDateOfTheMonth = YearMonth.of(year, month).atDay(1);
List<LocalDate> list = new ArrayList<>();
for (LocalDate date = firstDateOfTheMonth; !date
.isAfter(firstDateOfTheMonth.with(TemporalAdjusters.lastDayOfMonth())); date = date.plusDays(1))
if (date.getDayOfWeek() == DayOfWeek.SATURDAY || date.getDayOfWeek() == DayOfWeek.SUNDAY)
list.add(date);
return list;
}
}
从 Trail: Date Time 了解有关现代日期时间 API 的更多信息。
* 出于任何原因，如果您必须坚持使用 Java 6 或 Java 7，您可以使用 ThreeTen-Backport，它将大部分 java.time 功能向后移植到 Java 6 和 7 . 如果您正在为一个 Android 项目工作并且您的 Android API 级别仍然不符合 Java-8，请检查 Java 8+ APIs available through desugaring 和 How to use ThreeTenABP in Android Project。
【讨论】：
最简单的方法是遍历一个月中的所有日子，并检查每一天的星期几。例如：
// This takes a 1-based month, e.g. January=1. If you want to use a 0-based
// month, remove the "- 1" later on.
public int countWeekendDays(int year, int month) {
Calendar calendar = Calendar.getInstance();
// Note that month is 0-based in calendar, bizarrely.
calendar.set(year, month - 1, 1);
int daysInMonth = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
int count = 0;
for (int day = 1; day <= daysInMonth; day++) {
calendar.set(year, month - 1, day);
int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
if (dayOfWeek == Calendar.SUNDAY || dayOfweek == Calendar.SATURDAY) {
count++;
// Or do whatever you need to with the result.
}
}
return count;
}
我绝对肯定有更有效的方法来做到这一点 - 但这是我开始的，当我发现它太慢时进行优化。
请注意，如果您能够使用Joda Time，那会让您的生活更轻松...
【讨论】：
试试这个：
import java.util.Calendar;
import java.util.GregorianCalendar;
public class Sundays {
public static void main(String[] args) {
int year = 2012;
// put the month you want
int month = Calendar.JANUARY;
Calendar cal = new GregorianCalendar(year, month, 1);
do {
int day = cal.get(Calendar.DAY_OF_WEEK);
if (day == Calendar.SATURDAY || day == Calendar.SUNDAY) {
System.out.println(cal.get(Calendar.DAY_OF_MONTH));
}
cal.add(Calendar.DAY_OF_YEAR, 1);
} while (cal.get(Calendar.MONTH) == month);
}
}
【讨论】：
根据上一个答案，我有一个小的修改 当您找到第一个星期六和星期日时，您可以简单地添加 7 天，直到更改月份。
【讨论】：
请通过这个方法，我遇到了很多最后我创建了自己的。
public static int getDayDiff(String dateFrom, String dateTo){ // DD/MM/YYYY
Timestamp tDtF = getTimestampDDmmYYYY(dateFrom);//returning timestamp from / DD/MM/YYYY
Timestamp tDtT = getTimestampDDmmYYYY(dateTo);
Calendar dtF = new GregorianCalendar();
Calendar dtT = new GregorianCalendar();
dtF.setTimeInMillis(tDtF.getTime());
dtT.setTimeInMillis(tDtT.getTime());
int count = 0;
while(dtF.before(dtT)){
count++;
dtF.add(Calendar.DAY_OF_YEAR, 1);
}
return count;
}
public static int countDateSatOrSun(String dateFrom, String dateTo){//DD/MM/YYYY
Timestamp tDtF = getTimestampDDmmYYYY(dateFrom);//returning timestamp from / DD/MM/YYYY
Timestamp tDtT = getTimestampDDmmYYYY(dateTo);
Calendar dtF = new GregorianCalendar();
Calendar dtT = new GregorianCalendar();
dtF.setTimeInMillis(tDtF.getTime());
dtT.setTimeInMillis(tDtT.getTime());
int count = 0;
while(dtF.before(dtT)){
if((dtF.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY| dtF.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY))
count++;
dtF.add(Calendar.DAY_OF_YEAR, 1);
}
return count;
}
它会给你准确的结果。
【讨论】：