[英]Get week start and end days from week number
我想獲取給定周數的開始和結束日期。 我嘗試了以下代碼,但它總是返回相同的日期(當前周)
val c: Calendar = Calendar.getInstance()
val week = 39
c.set(Calendar.WEEK_OF_YEAR, week)
val firstDayOfWeek = c.firstDayOfWeek
c.set(Calendar.DAY_OF_WEEK,firstDayOfWeek)
startDate = SimpleDateFormat("yyyy-MM-dd",Locale.getDefault()).format(c.time).toString()
c.set(Calendar.DAY_OF_WEEK, firstDayOfWeek+6)
endDate = SimpleDateFormat("yyyy-MM-dd",Locale.getDefault()).format(c.time).toString()
我通過在使用之前額外調用c.time
來解決它。 這是工作代碼:
val c: Calendar = Calendar.getInstance()//Locale.getDefault())
val week = 39
c.set(Calendar.WEEK_OF_YEAR, week)
val t = c.time;
val firstDay = c.firstDayOfWeek
c.set(Calendar.DAY_OF_WEEK,firstDay)
startDate = SimpleDateFormat("yyyy-MM-dd",Locale.getDefault()).format(c.time).toString()
c.set(Calendar.DAY_OF_WEEK,firstDay+6)
endDate = SimpleDateFormat("yyyy-MM-dd",Locale.getDefault()).format(c.time).toString()
無法理解它的工作原理,在閱讀此https://developer.android.com/reference/java/util/Calendar#field-manipulation后嘗試
您一定遺漏了某些東西或犯了一些基本錯誤。 下面給出證明:
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
int week = 39;
Calendar c = Calendar.getInstance();
c.set(Calendar.WEEK_OF_YEAR, week);
int firstDayOfWeek = c.getFirstDayOfWeek();
// Start date
c.set(Calendar.DAY_OF_WEEK, firstDayOfWeek);
String startDate = sdf.format(c.getTime());
System.out.println(startDate);
// End date
c.set(Calendar.DAY_OF_WEEK, firstDayOfWeek + 6);
String endDate = sdf.format(c.getTime());
System.out.println(endDate);
}
}
輸出:
2020-09-21
2020-09-27
注意:我不知道 Kotlin 但 AFAIK,你也可以在 Kotlin 中運行 Java 代碼。 如果您想堅持使用 Kotlin 語法,我希望您能夠輕松地將其轉換為 Kotlin 語法。
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