Question

I have this code and when I run the script, I pass in valid parameters, but I keep on getting a NPE.
Help?

Code:

private static Date getNearestDate(List<Date> dates, Date currentDate) {
    long minDiff = -1, currentTime = currentDate.getTime();
    Date minDate = null;
    if (!dates.isEmpty() && currentDate != null) {
        for (Date date : dates) {
            long diff = Math.abs(currentTime - date.getTime());
            if ((minDiff == -1) || (diff < minDiff)) {
                minDiff = diff;
                minDate = date;
            }
        }
    }
    return minDate;
}

I get the NullPointerException from line 2 of the code above and I use the following code to pass in thisDate as the currentDate variable.

Date thisDate = null;
try {
    thisDate = (new SimpleDateFormat("MM/dd/yyyy")).parse(Calendar.getInstance().getTime().toString());
} catch (Exception e) {}

Answer 1

Since you’ve indicated that the NullPointerException is thrown on line 2, we can deduce that you’re passing in null for the currentDate argument. currentDate.getTime() is the only part of line 2 that can cause a NullPointerException.

Update:

I just wrote the following Test.java code to really understand what your problem is:

import java.util.*;
import java.text.*;

class Test {
    public static void main(String[] args) {
        Date thisDate = null;
        try {
            thisDate = (new SimpleDateFormat("MM/dd/yyyy")).parse(Calendar.getInstance().getTime().toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

When I run it, I get:

java.text.ParseException: Unparseable date: "Sat Aug 20 12:42:30 PDT 2011"
    at java.text.DateFormat.parse(DateFormat.java:337)
    at Test.main(Test.java:8)

So the problem is that your SimpleDateFormat.parse() expects the month/day/year format, but the Date class’s toString() method is giving you something different.

It seems as though all you really want is the current date. Why bother formatting it? Just trim it down to this and be done with it:

Date thisDate = new Date(); // this gives you the current date