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  1. /* package whatever; // don't place package name! */
  2. import java.text.SimpleDateFormat;
  3. import java.text.ParseException;
  4.  
  5. import java.util.Calendar;
  6. import java.util.Date;
  7. import java.util.HashSet;
  8. import java.util.Set;
  9. import java.util.Map;
  10. import java.util.TreeMap;
  11.  
  12.  
  13. /* Name of the class has to be "Main" only if the class is public. */
  14. class Ideone
  15. {
  16. 	public static void main (String[] args) throws java.lang.Exception
  17. 	{
  18. 	  Set<MyDate> allDates = getAllDates();
  19.       Map<String, Set<MyDate>> map = new TreeMap<>();
  20.       for (MyDate date : allDates) {
  21.         String key = date.getWeekStamp();
  22.         if (map.get(key) == null) {
  23.           map.put(key, new HashSet<MyDate>());
  24.         }
  25.         map.get(key).add(date);
  26.       }
  27.       printDates(map);
  28. 	}
  29.  
  30. 	public static Set<MyDate> getAllDates() {
  31.        String dateFormat = "MM/dd/yyyy";
  32.        String[] inputDates = {
  33.            "04/01/2015",
  34.            "04/02/2015",
  35.            "04/03/2015",
  36.            "04/04/2015",
  37.            "04/05/2015",
  38.            "04/06/2015",
  39.            "04/07/2015",
  40.            "04/08/2015",
  41.            "04/09/2015"};
  42.  
  43.        Set<MyDate> dates = new HashSet<>(inputDates.length);
  44.        for (String s : inputDates) {
  45.          MyDate date = new MyDate(s, dateFormat);
  46.          dates.add(date);
  47.        }
  48.        return dates;
  49.     }
  50.  
  51.     public static void printDates(Map<String, Set<MyDate>> map) {
  52.        int week = 0;
  53.        for (Set<MyDate> set : map.values()) {
  54.           week++;
  55.           System.out.println("Week : " + week);
  56.           for (MyDate date : set) {
  57.             System.out.println(date.getDate());  
  58.           }
  59.         }
  60.     }
  61.  
  62.     private static class MyDate {
  63.       final Calendar cal;
  64.  
  65.       public MyDate (String strDate, String dateFormat) {
  66.         cal = Calendar.getInstance();
  67.         try {
  68.           SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
  69.           Date date = sdf.parse(strDate);
  70.           cal.setTime(date);
  71.         }
  72.         catch (ParseException e) {
  73.           throw new IllegalArgumentException("Invalid date " + strDate);
  74.         }
  75.       }
  76.  
  77.       public String getWeekStamp() {
  78.         return cal.get(Calendar.YEAR) + "-" + cal.get(Calendar.WEEK_OF_YEAR);
  79.       }
  80.  
  81.       public Date getDate() {
  82.         return cal.getTime();
  83.       }
  84.     }
  85.  
  86. }
Success #stdin #stdout 0.16s 321152KB
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stdin
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Standard input is empty
stdout
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Week : 1
Wed Apr 01 00:00:00 GMT 2015
Sat Apr 04 00:00:00 GMT 2015
Thu Apr 02 00:00:00 GMT 2015
Fri Apr 03 00:00:00 GMT 2015
Week : 2
Sun Apr 05 00:00:00 GMT 2015
Tue Apr 07 00:00:00 GMT 2015
Thu Apr 09 00:00:00 GMT 2015
Mon Apr 06 00:00:00 GMT 2015
Wed Apr 08 00:00:00 GMT 2015
https://ideone.com/uw5Caa
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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