AndroidStudio Calendar.get(Calendar.DAY_OF_MONTH)

问题:

I have a problem with my calendar. Here is the code:

Calendar mCalendar = Calendar.getInstance();
mToday[0] = mCalendar.get(Calendar.DAY_OF_MONTH);
mToday[1] = mCalendar.get(Calendar.MONTH); // zero based
mToday[2] = mCalendar.get(Calendar.YEAR);

Can not run my project because AndroidStudio shows error on the Calendar.DAY_OF_MONTH, Calendar.MONTH etc... I get nullPointException while running in emulator

It sais that

Must be one of: java.util.Calendar.DAY_OF_MONTHjava.util.Calendar.MONTH etc...

I don't understand this error because Calendar.MONTH is one of java.util.calendar.MONTH

I have an import for it

import java.util.Calendar;

Sorry I missed that it's initialized but there is an other class where I want to use Calendar.MONTH and so on like this:

mCalendarToday = Calendar.getInstance();

...

int dayOfWeek = mCalendar.get(Calendar.DAY_OF_WEEK);
int firstDay = getDay(mCalendar.get(Calendar.DAY_OF_WEEK);

OR

private Calendar mCalendarToday;

...

private boolean isToday(int day, int month, int year) {
    if (mCalendarToday.get(Calendar.MONTH) == month
        && mCalendarToday.get(Calendar.YEAR) == year
        && mCalendarToday.get(Calendar.DAY_OF_MONTH) == day) {
        return true;
    }
    return false;
}

Here shows error too. And all the other lines where I would use.

回答1:

It looks like a bug of Android Studio: 0.5.5

see http://code.google.com/p/android/issues/detail?id=68758

回答2:

I do believe that the way you access the calendar is correct.

I'm guessing the int[] you try to add the values to is not initialized. You must call

int[] mToday = new int[3];

回答3:

Hardcoded. But must work.

    int[] mToday = new int[]{};
    java.util.Calendar calendar = java.util.Calendar.getInstance();
    mToday[0] = calendar.get(java.util.Calendar.DAY_OF_MONTH);
    mToday[1] = calendar.get(java.util.Calendar.MONTH);
    mToday[2] = calendar.get(java.util.Calendar.YEAR);

回答4:

maybe you did not initialize you field. I tried it in Eclipse and this worked

int[] mToday = new int[10];
Calendar mCalendar = Calendar.getInstance();
mToday[0] = mCalendar.get(Calendar.DAY_OF_MONTH);
mToday[1] = mCalendar.get(Calendar.MONTH); // zero based
mToday[2] = mCalendar.get(Calendar.YEAR);