how to parse a csv file which has some null value in java

Question

I want to parse csv like following :

12:50 AM,11.0,10.0,94,1013,10.0,NNW,14.8,-,N/A,,Mostly Cloudy,330,2011-10-27 23:50:00

for parsing it I use a code like below :

while((mylines = rdr.readLine()) != null)
        {   
            Pattern p = Pattern.compile("<br />");
            mylines=mylines.replaceAll("<br />", "");
            System.out.println(mylines);
            StringTokenizer st = new StringTokenizer(mylines , ",");
            while(st.hasMoreTokens())
            {
                System.out.println(st.nextToken());
            }
        }

for the 10th element which I call it Null I don't get any token response which is not good. how can I get token for all the elements?

regards

Why does your CSV file contain html breaks?

Thomas Jungblut
– Thomas Jungblut

2011-11-27 13:00:21 +00:00
Commented Nov 27, 2011 at 13:00 — Thomas Jungblut
– Thomas Jungblut, Commented Nov 27, 2011 at 13:00
what's the expected output and what's the actual output?

happymeal
– happymeal

2011-11-27 13:00:32 +00:00
Commented Nov 27, 2011 at 13:00 — happymeal
– happymeal, Commented Nov 27, 2011 at 13:00

GETah · Accepted Answer · 2011-11-27 13:00:12Z

3

That is the expected behavior of the StringTokenizer class. You can always force your program to return something, "***" for example for empty tokens by adding the following line right before splitting your string:

mylines=mylines.replaceAll(",,", ",***,");

In this case, the StringTokenizer will return *** instead of null

answered Nov 27, 2011 at 13:00

GETah

21.5k7 gold badges67 silver badges110 bronze badges

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

1 Comment

Shahood ul Hassan Over a year ago

What if the first value is null?

Amos M. Carpenter · Accepted Answer · 2011-11-27 13:01:21Z

1

If you're comfortable using a third-party library, use Apache's commons-lang and try StringUtils.splitPreserveAllTokens() - see the API doc.

answered Nov 27, 2011 at 13:01

Amos M. Carpenter

4,9584 gold badges47 silver badges74 bronze badges

Comments

mort · Accepted Answer · 2011-11-27 13:01:07Z

0

At the tenth position, you have ,,, which is an empty string, which in Java is represented by a null value. To avoid that the null value is printed, do something like

String str;
if((str = st.nextToken())!=null) {
  System.out.println(str);
} else {
  //print nothing or maybe a newline
}

answered Nov 27, 2011 at 13:01

mort

13.7k14 gold badges60 silver badges97 bronze badges

Comments

Giovanni · Accepted Answer · 2011-11-27 13:01:22Z

Hi here is a simple test case that parse the line and gives you all the elements including the empty one:

package com.sg2net.test;

public class TestSplit {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String[] data="12:50 AM,11.0,10.0,94,1013,10.0,NNW,14.8,-,N/A,,Mostly Cloudy,330,2011-10-27 23:50:00§".split(",");
        //String[] data="valore##valore1".split("##");
        System.out.println(data.length);
        if (data.length>0) {
            int i=1;
            for (String element : data) {
                if (element==null || element.length()==0) {
                    System.out.println("empty element at position " + i);
                }
                System.out.println(element);
                i++;
            }
        }

    }

}

rajah9 · Accepted Answer · 2011-11-27 13:01:54Z

0

Instead of null, look for a token whose length is > 0. In Java, the value null is not the same as an empty string.

answered Nov 27, 2011 at 13:01

rajah9

12.5k5 gold badges49 silver badges59 bronze badges

Comments

Michael Konietzka · Accepted Answer · 2011-11-27 13:07:03Z

0

ostermiller.org has a jar with nice utility-classes like CSV-Parser/Writer etc.

answered Nov 27, 2011 at 13:07

Michael Konietzka

5,4992 gold badges30 silver badges29 bronze badges

Collectives™ on Stack Overflow

how to parse a csv file which has some null value in java

6 Answers 6

1 Comment

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

1 Comment

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related