android：将任何日期转换为周数

Question

I'd like to find out the week number of the year from any given date.

I've tried this:

int date = 17.08.2015 or date = 17082015
Calendar calendar = Calendar.getInstance(); 
date = calendar.get(Calendar.WEEK_OF_YEAR);

I thought it would work, but it did not.

Background:

I have a DatepickerDialog where the user can select the date. But I just need the weeknumber.

Thanks in advance

Answer 1

It wont work like that. You need to parse the date first. Have a look at the following code.

String strDate = "17.08.2015";
DateFormat dateFormat = new SimpleDateFormat("dd.MM.yyyy");
Date date = null
try{
    date = dateFormat.parse(strDate)
}
catch(Exception e){
    e.printStackTrace();
}

Calendar now = Calendar.getInstance();
now.setTime(date);
int week = now.get(Calendar.WEEK_OF_YEAR);

So when you select a date from Calendar (DatePicker). Just format that date in a particular date format and parse it and set it in Calendar . Get the week number like using above code.

Answer 2

try this one...

   SimpleDateFormat dateFormat=new SimpleDateFormat("yyyy-MM-dd");
  Calendar calendar=Calendar.getInstance();
  String demoDate="2015-01-15 11:09:00";
        try{
            calendar.setTime(dateFormat.parse(demoDate));
            int weekOfYear=Calendar.WEEK_OF_YEAR);
        }catch(Exception e){
            e.printStackTrace();
        }  

for more info try this link for simple date format: http://developer.android.com/reference/java/text/SimpleDateFormat.html

Answer 3

You can get week number using this method.

public int getDayOfWeek(Date date) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        return c.get(Calendar.DAY_OF_WEEK);
}

you have to pass formatted date to this method and it returns week number.

EDIT1:

SimpleDateFormat format = new SimpleDateFormat("EEEE", Locale.getDefault());;
Date date;
Calendar calendar = Calendar.getInstance();
try {
       date = format.parse(format.format(calendar.getTime()));
       int weekDay = getDayOfWeek(date);
    } catch (ParseException e) {
        e.printStackTrace();
    }

EDIT2:

String dtStart = "2010-10-15";  
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");  
try {  
    Date date = format.parse(dtStart);  
    //this date can be passed to getDayOfWeek method
} catch (ParseException e) {  
    // TODO Auto-generated catch block  
    e.printStackTrace();  
}

I hope it helps!

Answer 4

If you want you can also try this so you can get your current date as variable

 DateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
 String date_posted = df.format(Calendar.getInstance().getTime());

    Date date = null;

    try {

        date = df.parse(date_posted);

    } catch (ParseException e) {
        e.printStackTrace();
    }

    Calendar now = Calendar.getInstance();
    now.setTime(date);

    int week = now.get(Calendar.WEEK_OF_YEAR);

Answer 5

从谷歌搜索我找到了这个链接。一旦你能得到正确的解决方案，请检查这个