Java operations on the day of the week

In the most recent OA, I need to determine whether two dates are the same week and get the dates of Monday and Friday of the week based on a given date.

After completing the preceding tasks, I found that the calendar is indeed a powerful class.

The source code is provided below for the reference of the brothers.

/*
* Creation date: 2005-3-30

Package com. infoearth;

Import java. SQL. timestamp;
Import java. Text .*;
Import java. util .*;
/**
* @ Li chunlei
*
Public class manageweek {
// Determine whether two dates are in the same week
Boolean issameweekdates (date date1, date date2 ){
Calendar cal1 = calendar. getinstance ();
Calendar cal2 = calendar. getinstance ();
Cal1.settime (date1 );
Cal2.settime (date2 );
Int subyear = cal1.get (calendar. Year)-cal2.get (calendar. year );
If (0 = subyear ){
If (cal1.get (calendar. week_of_year) = cal2.get (calendar. week_of_year ))
Return true;
}
Else if (1 = subyear & 11 = cal2.get (calendar. month )){
// If the last week of March spans the first week of the next year, the last week is counted as the first week of the next year.
If (cal1.get (calendar. week_of_year) = cal2.get (calendar. week_of_year ))
Return true;
}
Else if (-1 = subyear & 11 = cal1.get (calendar. month )){
If (cal1.get (calendar. week_of_year) = cal2.get (calendar. week_of_year ))
Return true;
}
Return false;
}
 
 
// Generate the weekly Sequence
Public static string getseqweek (){
Calendar c = calendar. getinstance (locale. China );
String week = integer. tostring (C. Get (calendar. week_of_year ));
If (Week. Length () = 1) Week = "0" + Week;
String year = integer. tostring (C. Get (calendar. Year ));
Return year + Week;

}

// Obtain the Monday date
Public static string getmonday (date ){
Calendar c = calendar. getinstance ();
C. settime (date );
C. Set (calendar. day_of_week, calendar. Monday );
Return new simpledateformat ("yyyy-mm-dd"). Format (C. gettime ());
}


// Obtain the Friday date
Public static string getfriday (date ){
Calendar c = calendar. getinstance ();
C. settime (date );
C. Set (calendar. day_of_week, calendar. Friday );
Return new simpledateformat ("yyyy-mm-dd"). Format (C. gettime ());
}

// The day before or after the current date

Public static string afternday (int n ){
Calendar c = calendar. getinstance ();
Dateformat df = new simpledateformat ("yyyy-mm-dd ");
C. settime (new date ());
C. Add (calendar. Date, N );
Date D2 = C. gettime ();
String S = DF. Format (D2 );
Return S;
}

Public static void main (string [] ARGs ){

}

}

I often encounter the problem of converting a string into a date. In fact, there are three sentences:

String mystring = "2005/12/20 ";

Simpledateformat SDF = new simpledateformat ("yyyy/mm/DD", locale. China );
Date d = SDF. parse (mystring );

The following is an example.

Package formatdatetime;

Import java. Text .*;
Import java. util .*;

/**
* @ Author Administrator
*
* To change the template of the type comment generated by todo, go
* Window-preferences-Java-code style-Code Template
*/
Public class stringtodatetimetest {

Public static void main (string [] ARGs ){

String mystring = "Tue Oct 18 04:11:56 CST 2005 ";
// String mystring = "2005/12/20 ";
Try {
Simpledateformat SDF = new simpledateformat ("eee Mmm dd hh: mm: ss zzz yyyy", locale. US );
// Simpledateformat SDF = new simpledateformat ("yyyy/mm/DD", locale. China );
Date d = SDF. parse (mystring );
Calendar c = calendar. getinstance ();
C. settime (d );
String S = new simpledateformat ("yyyy-mm-dd"). Format (C. gettime ());
System. Out. println (s );

} Catch (exception e ){
E. printstacktrace ();
}
}
}