java - DatePickerDialog crash -

i'm android newbie...

this code:

final button taskdatebutton = (button)findviewbyid(r.id.tasktimebutton); taskdatebutton.setonclicklistener(new view.onclicklistener() {     @override     public void onclick(view v) {          datepickerdialog datepickerdialog = new datepickerdialog(taskactivity.this, new datepickerdialog.ondatesetlistener() {             @override             public void ondateset(datepicker view, int year, int monthofyear, int dayofmonth) {                  taskdatecalendar.set(calendar.year, year);                 taskdatecalendar.set(calendar.month, monthofyear);                 taskdatecalendar.set(calendar.day_of_month, dayofmonth);                 taskdate = taskdatecalendar.gettime();                 setdatebuttonswithdates();                 timepickerdialog timepickerdialog = new timepickerdialog(taskactivity.this, new timepickerdialog.ontimesetlistener() {                     @override                     public void ontimeset(timepicker view, int hourofday, int minute) {                         taskdatecalendar.set(calendar.hour_of_day, hourofday);                         taskdatecalendar.set(calendar.minute, minute);                         taskdate = taskdatecalendar.gettime();                         setdatebuttonswithdates();                     }                 }, taskdatecalendar.get(calendar.hour_of_day), taskdatecalendar.get(calendar.minute), false);                 timepickerdialog.show();              }         }, taskdatecalendar.get(calendar.year), taskdatecalendar.get(calendar.month), taskdatecalendar.get(calendar.day_of_month));         datepickerdialog.show();       } }); 

it seems crashing when loading datepickerdialog, on line:

datepickerdialog datepickerdialog = new datepickerdialog(taskactivity.this, new datepickerdialog.ondatesetlistener() { 

i looked around couldn't see what's causing this.

this error get:

java.lang.nullpointerexception: attempt invoke virtual method 'int java.util.calendar.get(int)' on null object reference 

any help?

thanks

your taskdatecalendar object seems null. call taskdatecalendar = calendar.getinstance() before taskdatecalendar.set(calendar.year, year).