How to send a Calendar object from one activity to another in android?

Question

I have a Calendar object having some date and time manually stored in by the user. I want this object to be available for use in the next activity.

How do i do it? The putextra method using Parcelable are giving discrepancies.

Answer 1

Calendar does not implement Parcelable.

It does look like it implements Serializable however, so you might be able to serialize it down into a string and pass that as an Extra to your other activity.

Another option you have is to use cal.getTimeInMillis() which will give you a long that you can add as an Extra to your intent. Then you can pull it out on the other side and make a new Calendar object and immediately call setTimeInMillis() on it so that it will be set to the same time as the Calendar object in the old activity.

Answer 2

cal.getTimeInMillis() is half right. The problem with just getTimeInMillis() is you lose Timezone information. So a Calendar variable in UTC will be converted to the local timezone when reading that value in, possibly changing the actual date.

I don't know if I have the perfect answer but I saved the time in milliseconds AND the timezone id so I could fully recreate the calendar object on the other side.

public void writeToParcel(Parcel out, int flags) {
    out.writeLong(mycal.getTimeInMillis());
    out.writeString(mycal.getTimeZone().getID());
}

private MyClassObject(Parcel in) {

    long milliseconds = in.readLong();
    String timezone_id = in.readString();

    mycal = new GregorianCalendar(TimeZone.getTimeZone(timezone_id));
    mycal.setTimeInMillis(milliseconds);

}

out.writeSerializable(); is an option but I have read that it is sluggish and does not perform well, so I opted to just avoid it.