date is null and crashing on a few devices

Question

I am using the this code to convert date time to unixtime gmt . It is working fine on most of the devices but it is crashing in a few . I am unable to determine the cause. How can I fix it ?

int gmtOffset = TimeZone.getDefault().getRawOffset() + TimeZone.getDefault().getDSTSavings();
        String dt="11-01-2016 5:8 AM";
        DateFormat format = new SimpleDateFormat("dd-MM-yyyy hh:mm a");
        format.setTimeZone(TimeZone.getTimeZone("GMT"));
        Date date = null;
        try {
            date = format.parse(dt);
            System.out.println("Date ->" + date);
        } catch (Exception e) {
            e.printStackTrace();
        }
        long unixtime = (date.getTime() -(gmtOffset))/1000;

error:

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'long java.util.Date.getTime()' on a null object reference

score 6 · Accepted Answer · edited May 23 '17 at 12:33

When the locale is not set to US English, the locale's Am/pm marker may be different. For example, in Chinese, the AM/PM maker will be 上午/下午.

Thus, to force use of AM/PM, you'd need to use a US date format:

DateFormat format = new SimpleDateFormat("dd-MM-yyyy hh:mm a", Locale.US)

I ran this code when in the US locale, and it worked fine. When I switched to Chiense, I got the message:

java.text.ParseException: Unparseable date: "11-01-2016 5:8 AM" (at offset 15)

Offset 15 is the AM/PM marker. Thus, when exiting the try/catch block, the date object will remain null, causing the NullPointerException when calling the getTime() method.

By the way, you might consider using Joda DateTime to get the Unix epoch, something along the lines of: Joda DateTime to Unix DateTime.

score 0 · Answer 2 · answered Jan 28 '16 at 16:58

0

Maybe the dtStart doesn't have the same format always (in this case it is hardcoded). If the format of dtStart is not correct after try catch block "date" is null and the app crashes at the last line because the date is null. (date.getTime())

answered Jan 28 '16 at 16:58

David Rauca

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But the same code works fine in other devices. It only crashes in a few devices . I mean the same hard-coded value – jason Jan 28 '16 at 17:01
Could you give me an example of a device where the app crashes? – David Rauca Jan 28 '16 at 17:02

score 0 · Answer 3 · answered Jan 28 '16 at 17:01

The exception is throw when date is null. And date will be null if dtStart can't be parsed. Try like this:

int gmtOffset = TimeZone.getDefault().getRawOffset() + TimeZone.getDefault().getDSTSavings();
String dtStart="11-01-2016 5:8 AM";
DateFormat format = new SimpleDateFormat("dd-MM-yyyy hh:mm a");
format.setTimeZone(TimeZone.getTimeZone("GMT"));
Date date = null;
long unixtime = 0;
try {
    date = format.parse(dtStart);
    System.out.println("Date ->" + date);
    unixtime = (date.getTime() -(gmtOffset))/1000;
} catch (Exception e) {
    e.printStackTrace();
}

date is null and crashing on a few devices

3 Answers3