How do I use System getProperty line separator toString

Question

I have a Tab-delimited String  representing a table  that is passed to my method  When I print it to the command line  it appears like a table with rows   http   i stack imgur com 2fAyq gif  The command window is correctly buffered  My thinking is that there is definitely a new line character before or after each row   My problem is that I want to split up the incoming string into individual strings representing the rows of the table  So far I have   private static final String newLine   System getProperty  line separator   toString    private static final String tab     t   private static String   rows       rows   tabDelimitedTable split newLine        problem is here  System out println    System out println                      start debug                          System out println  tabDelimitedTable contains newLine      True     False     System out println                       end debug                       System out println      output                       start debug                      False                      end debug                      Obviously there is something in the string telling the OS to start a new line  Yet it apparently contains no newline characters   Running the latest JDK on Windows XP SP3   Any Ideas

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The other responders are correct that split   takes a regex as the argument  so you ll have to fix that first  The other problem is that you re assuming that the line break characters are the same as the system default  Depending on where the data is coming from  and where the program is running  this assumption may not be correct

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Try BufferedReader readLine   instead of all this complication  It will recognize all possible line terminators

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On Windows  line separator is a CR LF combination  reference here    The Java String split   method takes a regular expression  So I think there s some confusion here

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Try this   rows   tabDelimitedTable split     r  n        This should work regardless of what line delimiters are in the input  and will ignore blank lines

User · Answer

I think your problem is that String split   treats its argument as a regex  and regexes treat newlines specially   You may need to explicitly create a regex object to pass to split    there is another overload of it  and configure that regex to allow newlines by passing MULTILINE in the flags param of Pattern compile     Docs

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Try  rows   tabDelimitedTable split       newLine           This should solve the regex problem   Also not that important but return type of  System getProperty  line separator     is String so no need to call toString

User · Answer

The problem  You must NOT assume that an arbitrary input text file uses the  correct  platform-specific newline separator  This seems to be the source of your problem  it has little to do with regex   To illustrate  on the Windows platform  System getProperty  line separator   is   r n   CR LF   However  when you run your Java code on this platform  you may very well have to deal with an input file whose line separator is simply   n   LF   Maybe this file was originally created in Unix platform  and then transferred in binary  instead of text  mode to Windows  There could be many scenarios where you may run into these kinds of situations  where you must parse a text file as input which does not use the current platform s newline separator    Coincidentally  when a Windows text file is transferred to Unix in binary mode  many editors would display  M which confused some people who didn t understand what was going on    When you are producing a text file as output  you should probably prefer the platform-specific newline separator  but when you are consuming a text file as input  it s probably not safe to make the assumption that it correctly uses the platform specific newline separator     The solution  One way to solve the problem is to use e g  java util Scanner  It has a nextLine   method that can return the next line  if one exists   correctly handling any inconsistency between the platform s newline separator and the input text file   You can also combine 2 Scanner  one to scan the file line by line  and another to scan the tokens of each line  Here s a simple usage example that breaks each line into a List lt String gt   The entire file therefore becomes a List lt List lt String gt  gt    This is probably a better approach than reading the entire file into one huge String and then split into lines  which are then split into parts        String text            row1 tblah tblah tblah n             row2 t1 t2 t3 t4 r n             row3 tA tB tC r             row4        System out println text           row1    blah    blah    blah         row2    1   2   3   4         row3    A   B   C         row4      List lt List lt String gt  gt  input   new ArrayList lt List lt String gt  gt          Scanner sc   new Scanner text       while  sc hasNextLine              Scanner lineSc   new Scanner sc nextLine    useDelimiter   t            List lt String gt  line   new ArrayList lt String gt             while  lineSc hasNext                  line add lineSc next                       input add line             System out println input            row1  blah  blah  blah    row2  1  2  3  4    row3  A  B  C    row4     See also   Effective Java 2nd Edition  Item 25  Prefer lists to arrays   Related questions   Validating input using java util Scanner - has many examples of usage Scanner vs  StringTokenizer vs  String Split

[java] How do I use System.getProperty("line.separator").toString()?

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