Escape sequence not working as desired

Question

I have to read a file and then write something to some output file. In both input and output files, I used pipeline delimiter :-

private static final String COLUMNDELIMITER = "\\|";

I can read the input file perfectly but for the output file, the lines are coming as below:

abc\|123\|kk

But I want it to be:

abc|123|kk

Why the same delimiter behaving differently for read and write?

When I am reading a line, I am using:

String[] elements = record.split(COLUMNDELIMITER); //works perfect

And while writing I am using:

String lineToWrite = String1 + COLUMNDELIMITER + String2 + COLUMNDELIMITER + String3 //Does not work rightly

Answer 1

String.split takes a regular expression, and a pipe ( | ) has special meaning, so it needs to be escaped. This is done using a backslash ( \\ ), which needs to be escaped in Java strings, so you need to use double-backslash (\\) in the string literal. However, when concatenating, you just need | , not \\| .

So, instead use:

private static final String COLUMNDELIMITER = "|";

And when splitting, quote it using java.util.regex.Pattern#quote :

String[] elements = record.split(Pattern.quote(COLUMNDELIMITER));

Your concatenation will then just work.