I have created an xml layout which is in effect a grid. I need to use it as a calendar and have read about the calendar class but i've been unable to get any of the code it suggests to work.
How would i go about displaying the current year,month and days in the various text views?
This is what i have so far:
Calendar c = Calendar.getInstance();
int month = c.get(Calendar.MONTH);
String month_name = Integer.toString(month);
TextView monthdisp = (TextView) findViewById(R.id.month_disp);
monthdisp.setText(month_name);
setContentView(R.layout.main);
However a null pointer excpetion is generated at monthdisp.setText(month_name);
See the Android Developers guide To get the current year, month and days you'd use the following:
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR); // get the current year
int month = cal.get(Calendar.MONTH); // month...
int day = cal.get(Calendar.DAY_OF_MONTH); // current day in the month
// sets your textview to e.g. 2012/03/15 for today
textview.setText("Year / month / day: "+ year + "/" + month + "/" + day);
Alternatively, you can use SimpleDateFormat like so:
// set-up the desired formatting
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Calendar cal = Calendar.getInstance();
Date now = cal.getTime(); // set the current datetime in a Date-object
// SimpleDateFormat.format( Date date ) returns a formatted string
// with the predefined format
String mTimeString = sdf.format( now ); // contains yyyy-MM-dd (e.g. 2012-03-15 for March 15, 2012)
TextView textView = new TextView(this);
textView.setText( mTimeString );
The other way around also works:
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
String mDateString = "14-05-2012";
Date mDate = sdf.parse( mDateString ); // returns a Date-object
// with date set to May 14, 2012
The other answers here provide good info about the Calendar class and date/time manipulation, but that's not why your code is throwing a NullPointerException:
TextView monthdisp = (TextView) findViewById(R.id.month_disp);
monthdisp.setText(month_name); // NPE here indicates monthdisp is null
Calling findViewById(R.id.month_disp) returned null. This is probably because you haven't inflated your view yet, or month_disp just isn't in your layout.
Typically, view inflation occurs in the Activity.onCreate() method, and you can do it in several ways, for instance setContentView(). Check that you are doing this before calling findViewById(), and that the layout you are inflating actually has that view in it.
Related
Actually i want to display a set of data with the start and end date of the week were that particular date falls on. In my emulator its working fine. Eg. If i give Apr 23 its giving me start date of the week as 22 Apr and end date as 28 Apr, but if i try to build the same code in my device its showing start date of the week as 27 Apr and end date as 28 Apr.
Piece of Code which i am using:
//to get first day of week
cal1.set(Calendar.DAY_OF_WEEK, 1);
int day1 = cal1.get(Calendar.DAY_OF_MONTH);
//to get last day of week
cal1.set(Calendar.DAY_OF_WEEK, 7);
int day7 = cal1.get(Calendar.DAY_OF_MONTH);
I don't know why you getting that data but this is how I get the first and last date, take look might help. (its written to give current week's first and last date, so might have to tweak it little bit.)
Calendar calendar = Calendar.getInstance();
Date date1 = calendar.getTime();
//current date to check that our week lies in same month or not
SimpleDateFormat checkformate = new SimpleDateFormat("MM/yyyy");
String currentCheckdate= checkformate.format(date1);
int weekn = calendar.get(Calendar.WEEK_OF_MONTH);
int month = calendar.get(Calendar.MONTH);
int year = calendar.get(Calendar.YEAR);
//resat calender without date
calendar.clear();
calendar.setFirstDayOfWeek(Calendar.MONDAY);
calendar.set(Calendar.WEEK_OF_MONTH,weekn);
calendar.set(Calendar.MONTH,month);
calendar.set(Calendar.YEAR,year);
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd/MM/yyyy");
Date datef = calendar.getTime();
//move date to 6 days + to get last date of week
Long timeSixDayPlus = calendar.getTimeInMillis()+518400000L;
Date dateL = new Date(timeSixDayPlus);
String firtdate = simpleDateFormat.format(datef);
String lastdate = simpleDateFormat.format(dateL);
String firtdateCheck = checkformate.format(datef);
String lastdateCheck = checkformate.format(dateL);
//if our week lies in two different months then we show only current month week part only
if (!firtdateCheck.toString().equalsIgnoreCase(currentCheckdate)) {
firtdate = "1" + "/" + calendar.get(Calendar.MONTH) + "/" + calendar.get(Calendar.YEAR);
}
if (!lastdateCheck.toString().equalsIgnoreCase(currentCheckdate)) {
int ma = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
lastdate = String.valueOf(ma) + "/" + calendar.get(Calendar.MONTH) + "/" + calendar.get(Calendar.YEAR);
}
Log.e("current","=>>"+firtdate+" to "+lastdate);
To get the first day of the week -
initialize the Calendar as per your need. in this case, I am getting the current date calendar.
set the current day of the week to the first day of the week.
get the corresponding date.
Calendar calendar = Calendar.getInstance();
//optional step
calendar.setFirstDayOfWeek(Calendar.SUNDAY);
calendar.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
int firstDateOfWeek = calendar.get(Calendar.DATE);
To get the last date of the week -
follow the step as above to initialize.
set the day of the week as Saturday.
get the corresponding date.
Calendar calendar = Calendar.getInstance();
//optional step
calendar.setFirstDayOfWeek(Calendar.SUNDAY);
calendar.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);
int lastDateOfWeek = calendar.get(Calendar.DATE);
In this way, you can get eh first and the last date for the week. one thing to keep in mind that I have set the first day of the week as SUNDAY. set as per your need. although it is purely optional to set the first day of the week. this gives you a more transparency in code.
During the signup process, I'm trying to implement a code that stores a date value into a string value in the following format: "dd-mm-yyyy".
So, on the onCreate() method part, I declared a DatePicker variable as follows:
DatePicker dob = (DatePicker) findViewById(R.id.dob);
And on the onClick() method part, I wrote a code to convert this DatePicker value into the String.
String entered_dob = dob.toString();
But later when I opened the database I found out that this only returns a value which looks nonsense. How should I implement in order to get what I wanted?
If you want to store your date as a String (which is not a good practice)
DatePicker datePicker ;
SimpleDateFormat dateFormatter ;
Date d ;
String entered_dob ;
datePicker = (DatePicker) findViewById(R.id.dob);
int day = datePicker.getDayOfMonth();
int month = datePicker.getMonth() + 1;
int year = datePicker.getYear()
d = new Date(year, month, day);
dateFormatter = new SimpleDateFormat("MM-dd-yyyy");
entered_dob = dateFormatter.format(d);
If you want to get the timestamp you can do it like this
Calendar calendar = new GregorianCalendar(year, month, day);
long enterded_dob_ts = calendar.getTimeInMillis();
I would recommend storing the timestamp.
Use the Calendar to create this value. This one you can easily store as long (or string if you really want this)
Checkout this Example
I am using DatePickerDialog to show the calender. I want to access First day and last day of the week of the date selected.
Here is what I have tried
this.tv_date.setText( new StringBuilder()
// Month is 0 based so add 1
.append(mDay).append("-")
.append(monthName).append("-")
.append(mYear).append(""));
tv_date.setHighlightColor(Color.CYAN);
String str=mDay+"-"+mMonth+"-"+mYear;
SimpleDateFormat sdf=new SimpleDateFormat("dd-MM-yyyy");
sdf.format(""+str); //here I am getting exception
Calendar cal=Calendar.getInstance();
int s= cal.getFirstDayOfWeek();
Toast.makeText(getApplicationContext(), "first day of the week : "+s, 1).show();
But I am getting "IllegalArguementException".
Please help me
Thanks
sdf.format(""+str); - is wrong. You either need to pass a Date object to it, or else, change it to sdf.parse(str); to get a Date object from it.
Edit:- To get the first day of the week, do this.
String str=mDay+"-"+mMonth+"-"+mYear;
SimpleDateFormat sdf=new SimpleDateFormat("dd-MM-yyyy");
Date myDate = new Date();
try{
myDate = sdf.parse(str);
}catch(ParseException pe){
// Do Something
}
Calendar cal = Calendar.getInstance();
cal.setTime(myDate);
cal.set(Calendar.DAY_OF_WEEK, 1);
int s = cal.get(Calendar.DATE);
Here is an example of calculating the first day of week.
private void firstDayOfThisWeek(){
DateTime today = DateTime.today(TimeZone.getDefault());
DateTime firstDayThisWeek = today; //start value
int todaysWeekday = today.getWeekDay();
int SUNDAY = 1;
if(todaysWeekday > SUNDAY){
int numDaysFromSunday = todaysWeekday - SUNDAY;
firstDayThisWeek = today.minusDays(numDaysFromSunday);
}
System.out.println("The first day of this week is : " + firstDayThisWeek);
}
Instead of assigning today you can assign any other day with exact format
I am getting date and time from DatePicker and TimePicker like:
int dateofmonth = date.getDayOfMonth();
int month = date.getMonth() + 1;
int year = date.getYear();
int hour = time.getCurrentHour();
int minutes = time.getCurrentMinute();
But i want date and time like this format:
Friday, December 14,2012 - 4:30 PM.
Any help?
formate it as you want ....
public void SetMyCustomFormat()
{
// Set the Format type and the CustomFormat string.
dateTimePicker1.Format = DateTimePickerFormat.Custom;
dateTimePicker1.CustomFormat = "put your formate here ";
}
for more help
http://msdn.microsoft.com/en-us/library/system.windows.forms.datetimepicker.customformat.aspx
You could try to use SimpleDateFormat, see SimpleDateFormat
Under the examples section is a date that represents your required format.
You need to create a Date Object first from Calendar, you can do as below:
Calendar cal= Calendar.getInstance();
cal.setTime(new Date());
int dateofmonth = date.getDayOfMonth();
int month = date.getMonth();
int year = date.getYear();
cal.set(dateofmonth, month, year);
Now create a SimpleDateFormat object, with the format, you desire, and format date with that format, by
String formattedDate=simpleDateFormat.format(cal.getTime());
If all you need is formatting a Date object in the current locale, you can use DateFormat:
Calendar date = Calendar.getInstance();
date.set(Calendar.YEAR, picker.getYear());
...
String str = DateFormat.getDateTimeInstance().format(date);
The method getDateTimeInstance() returns the preferred display for the current locale, which is desirable to internationalize your application because different locales have different preferences for the order of the components. For example:
US: Friday, December 14,2012 - 4:30 PM
Italy: Venerdì 14 Dicembre 2012, 16:30
In my app I have a date saved in a remote database that I want the date picker to be set to. I've researched and only found examples of setting the datepicker today's date via Calender java util. Example:
final Calendar c = Calendar.getInstance();
year = c.get(Calendar.YEAR);
month = c.get(Calendar.MONTH);
day = c.get(Calendar.DAY_OF_MONTH);
How can I use the Calendar to display my date from the database and not today's date? Do you have any suggestions or examples I can follow?
Update:
After experimenting with Calendar I tried to use
// set Date
String eventYear =date.substring(0,4);
String eventDay =date.substring(5,7);
String eventMonth =date.substring(8,10);
//convert string to int for because calendar only takes int: set(int,int)
int month = Integer.parseInt(eventMonth);
final Calendar c = Calendar.getInstance();
mMonth=c.get(c.set(Calendar.MONTH, Calendar.month));
// or mMonth=c.get(Calendar.MONTH, Calendar.month);
Generates error that says cannot convert int to void.
How can I use Calendar to set it to a specific date? According to google's developers site I should be able to do this.
http://developer.android.com/reference/java/util/Calendar.html
example:
set(Calendar.MONTH, Calendar.SEPTEMBER)
I'd like the date to be display in the datepicker from the server as a default value.
U can use the updateDate(year, month, day_of_month);
date picker returns integer values of day, month and year. so the parameters must be integer values. and the integer value for the month jan in the date picker is 0.
i needed to put the date extracted from a database into a datepicker. I wrote the following code and it works.
DatePicker DOB;
SQLiteDatabase db;
DOB=(DatePicker)findViewById(R.id.datePicker1);
db = openOrCreateDatabase("BdaySMS", SQLiteDatabase.CREATE_IF_NECESSARY, null);
Cursor cur = db.rawQuery("select * from BdaySMS where ph='"+pn+"';", null);//pn is the phone no.
if(cur.moveToFirst())
{
name.setText(cur.getString(0));
phone.setText(cur.getString(1));
DOB.updateDate(Integer.parseInt(cur.getString(4)),Integer.parseInt(cur.getString(3)),Integer.parseInt(cur.getString(2)));
message.setText(cur.getString(5));
}
Use JodaTime
Here's a simple example of how I set a DatePicker and TimePicker from a DateTime object, which could be the current date or any date from the past or future (the attribute in this case is called inspected_at):
DatePicker dp = (DatePicker) findViewById(R.id.inspected_at_date);
TimePicker tp = (TimePicker) findViewById(R.id.inspected_at_time);
DateTime inspected_at = DateTime.now().minusYears(1); // Typically pulled from DB.
int year = inspected_at.getYear() ;
int month = inspected_at.getMonthOfYear() - 1; // Need to subtract 1 here.
int day = inspected_at.getDayOfMonth();
int hour = inspected_at.getHourOfDay();
int minutes = inspected_at.getMinuteOfHour();
dp.updateDate(year, month, day);
tp.setCurrentHour(hour);
tp.setCurrentMinute(minutes);
Hope that helps.
JP