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https://issues.apache.org/jira/browse/SANDBOX-209?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12574319#action_12574319
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Trejkaz commented on SANDBOX-209:
---------------------------------
The following methods should throw NullPointerException or
IllegalArgumentException if the parameter itself is null, depending on your
preference:
public void println(String[] values) {
public void println(String[][] values) {
public void printlnComment(String comment) {
The following two methods should behave similarly with null values:
public void println(String value) {
public void print(String value) {
(well, I guess println(String) just does print(String) followed by println()...)
I think leaving it completely empty is okay. So for instance...
printer.println(new String[] { "1", null, "3" });
This would result in:
1,,3
(I'll use 1,,3 and 1,"",3 to describe the two possible forms from here on.)
The issue comes down to how to distinguish null from "" when reading CSV back
in. Many people have this problem with CSV in other systems and there is no
good solution. Some applications say that 1,,3 is a null and 1,"",3 is "" but
this isn't standardised at all.
You can test spreadsheet app behaviour by entering a single quote by itself to
create a proper empty string. Excel's behaviour is to export both as 1,,3.
OpenOffice Calc appears to assume that a single quote means a string which is
the single quote (a bug, probably.)
So IMO, leaving both as empty is acceptable, and at least consistent with apps
which do distinguish between the two internally even if they don't export them
in different ways.
Later, a new CSVStrategy parameter might be introduced, something like
get/setQuoteEmptyStrings -- assuming users actually need to distinguish between
the two. Personally when reading from a CSV file I use StringUtils.isEmpty
anyway, so whether it's null or "" doesn't matter to me.
As for ignoreEmptyLines, it's my belief that this should only apply to truly
empty lines. If users insist on having a CSV file with a single column then
yes, there is a risk of this single column being null and thus empty, and thus
generating a blank line. On the other hand, I don't think many users would be
using a CSV library if their data is only in a single column -- and two column
data wouldn't have this issue as they should at the very least have a single
comma even if both cells are blank for a given row (both Excel and
OpenOffice.org do it this way.)
> NullPointerException
> --------------------
>
> Key: SANDBOX-209
> URL: https://issues.apache.org/jira/browse/SANDBOX-209
> Project: Commons Sandbox
> Issue Type: Bug
> Components: CSV
> Affects Versions: Nightly Builds
> Reporter: Andriy Sholokh
> Fix For: Nightly Builds
>
>
> If
> public void print(String value) method of CSVPrinter class gets null
> parameter it throws NullPointerException.
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