The special case for non-multiline strings aside, look at the following example;
String s = "abc\ndef\nghi\n";
System.out.println(s.lines().collect(Collectors.joining("\n", "",
"\n")).lines().count());
System.out.println(s.lines().collect(Collectors.joining("\n")).lines().count());
As expected the result is
3
3
Now try
String s = "abc\ndef\n\n";
System.out.println(s.lines().collect(Collectors.joining("\n", "",
"\n")).lines().count());
System.out.println(s.lines().collect(Collectors.joining("\n")).lines().count());
The result is now
3
2
We started with 3 lines but ended up with 2 lines. This is because
String::split(“\\R”), BufferedReader::lines() and String::lines() have the
definition of line-ness as
* A <i>line</i> is either a sequence of zero or more characters
* followed by a line terminator, or it is a sequence of one or
* more characters followed by the end of the string. A
* line does not include the line terminator.
So if we didn’t add the final line terminator, then we would drop a line every
time we had an empty line at the end of the string.
Adding to the cases above
String s = "abc\ndef\n \n".indent(-3);
System.out.println(s.lines().collect(Collectors.joining("\n", "",
"\n")).lines().count());
System.out.println(s.lines().collect(Collectors.joining("\n")).lines().count());
Would also result in
3
2
Thus, it is a line terminator and not a line separator. As a bonus. the use
cases we see with String::indent(int n) are consistent with having a final line
terminator.
String composite = head.indent(4) + body.indent(8) + tail.indent(4);
vs
String composite = head.indent(4) + "\n" + body.indent(8) + "\n" +
tail.indent(4) + "\n";
Your point about consistency with non-multiline is valid, and we will drop the
special case since it is inconsistent with the spec. The correction will treat
non-multiline strings as single line. (Adding indentation to simple strings
can easily be done with " ".repeat(n) and removing indentation with
s.substring(n).)
Note:
"a single line".lines().count() == 1
"".lines().count() == 0
Cheers,
— Jim
> On Aug 29, 2018, at 6:48 PM, Ivan Gerasimov <[email protected]> wrote:
>
> Hi Jim!
>
> Why a new line is always added to the result of indent(int):
>
> return stream.collect(Collectors.joining("\n", "", "\n"));
> Because of this, a call to str.indent(0) depends on whether the string is
> single-line or multi-line: In the former case it is unchanged, while in the
> later case it gets a newline appended.
> Moreover, if a multi-line string already ends with a new line, then a new
> new-line is not appended, which seems inconsistent.
>
> I think, it may be better to always preserve the number of existing trailing
> new lines.
>
> With kind regards,
> Ivan
>
>
> On 8/29/18 7:00 AM, Jim Laskey wrote:
>> Please review the code for String::align and String::indent at the link
>> below.
>>
>> Notes:
>> Includes a private version of String::isMultiline() which may be made
>> into a public method at some future date
>> Includes minor correctness clean up of StringLatin1.java,
>> StringUTF16.java
>>
>> webrev: http://cr.openjdk.java.net/~jlaskey/8200434/webrev/index.html
>> <http://cr.openjdk.java.net/~jlaskey/8200434/webrev/index.html>
>> jbs: https://bugs.openjdk.java.net/browse/JDK-8200434
>> <https://bugs.openjdk.java.net/browse/JDK-8200434>
>>
>> Cheers,
>>
>> — Jim
>>
>>
>
> --
> With kind regards,
> Ivan Gerasimov
