Parsing String to Calendar in Java?

Question

I am having trouble parsing a string to a calendar object in java by pulling it from an XML element (I'm writing an android app) so I can calculate the length of time between the time in the string and the current time. I am brand new to java and come from the .NET world, so any additional background here can be really helpful.

The code I am trying to use is:

// Using this class to define the format for date parsing.
SimpleDateFormat sdf = new SimpleDateFormat("yyyymmdd HH:mm:ss", Locale.ENGLISH);

// readArrivalValue reads the element from XML, which seems to be working.
String prdt = readArrivalValue(parser, "prdt");
// At this point prdt evaluates to the correct value: "20150331 20:14:40"

Date datePRDT = sdf.parse(prdt);
// datePRDT doesn't seem to be set properly. It evaluates to:
//    datePRDT = {java.util.Date@830031077456}"Sat Jan 31 20:14:40 CST 2015"
//      milliseconds = 1422761216000

// element.prdt is of type Calendar. Nothing is done to this prior to this statement.
element.prdt.setTime(datePRDT); // This throws a null pointer exception

Sorry, should have specified that - Calendar. I'll edit the post. And now I'm realizing I probably have to initialize that in some way, as it might be a reference type? — tarun713
– tarun713, Commented Apr 1, 2015 at 2:40
I am guessing that datePRDT is not causing the NPE but either element or element.prdt object is causing it. Make sure you initialized them — Rod_Algonquin
– Rod_Algonquin, Commented Apr 1, 2015 at 2:42
That makes sense, as it's not initialized. Is it best practice to use Calendar.getInstance() in this case to initialize, or just new GregorianCalendar() ? And why is my parse coming back with the wrong value? — tarun713
– tarun713, Commented Apr 1, 2015 at 2:45
I would recommend using the getInstance that it will directly use the date of the system where you are running it. — Rod_Algonquin
– Rod_Algonquin, Commented Apr 1, 2015 at 2:46

Ravi K Thapliyal · Accepted Answer · 2015-04-01 02:50:08Z

1

Two issues with your code:

Fix your SimpleDateFormat pattern as you're parsing minutes mm in place of months MM too!

new SimpleDateFormat("yyyyMMdd HH:mm:ss", Locale.ENGLISH);
                          ^

You most likely forgot to initialize your Calendar instance and hence get an NPE.
```
element.prdt = Calendar.getInstance();
element.prdt.setTime(datePRDT);
```

answered Apr 1, 2015 at 2:50

Ravi K Thapliyal

51.9k9 gold badges80 silver badges90 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Parsing String to Calendar in Java?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related