de.mhus.lib.core.io

Class CSVReader

java.lang.Object

de.mhus.lib.core.io.CSVReader

public class CSVReader
extends Object

Read CSV (Comma Separated Value) files. This format is used my Microsoft Word and Excel. Fields are separated by commas, and enclosed in quotes if they contain commas or quotes. Embedded quotes are doubled. Embedded spaces do not normally require surrounding quotes. The last field on the line is not followed by a comma. Null fields are represented by two commas in a row. We optionally trim leading and trailing spaces on fields, even inside quotes. File must normally end with a single CrLf, other wise you will get a null when trying to read a field on older JVMs.

Author:

copyright (c) 2002-2006 Roedy Green Canadian Mind Products version 1.0 2002 March 27
1.1 2002 March 28 - close - configurable separator char - no longer sensitive to line-ending convention. - uses a categorise routine to massage categories for use in case clauses. - faster skipToNextLine
1.2 2002 April 23 - put in to separate package
1.4 2002 April 19 - fix bug if last field on line is empty, was not counting as a field.
1.6 2002 May 25 - allow choice of " or ' quote char.
1.7 2002 August 29 - getAllFieldsInLine
1.8 2002 November 12 - allow Microsoft Excel format fields that can span several lines. sponsored by Steve Hunter of agilense.com
1.9 2002 November 14 - trim parameter to control whether fields are trimmed of lead/trail whitespace (blanks, Cr, Lf, Tab etc.)
2.0 2003 August 10 - getInt, getLong, getFloat, getDouble
2.1 2005-07-16 - reorganisation, new bat files.
2.2 2005-08-28 - add CSVAlign and CSVPack to the suite.

There is another CSVReader at: at http://ostermiller.org/utils/ExcelCSV.html If this CSVReader is not suitable for you, try that one.
There is one written in C# at http://www.csvreader.com/
Future ideas:
1. allow specify various comment chars that mean the rest of the line should be ignored. e.g. ; ! #. These chars have to be in quotes in data then.
2. allow \ to be used for quoting characters.

Field Summary

Fields

Modifier and Type	Field and Description
static char	NO_QUOTS

Constructor Summary

Constructors

Constructor and Description
CSVReader(Reader r) convenience Constructor, default to comma separator, " for quote, no multiline fields, with trimming.
CSVReader(Reader r, char separator, char quote, boolean allowMultiLineFields, boolean trim) Constructor

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close the Reader.
String	get() Read one field from the CSV file
String	get(int row)
String	get(String row)
String[]	getAllFieldsInLine() Get all fields in the line
double	getDouble() Read one double field from the CSV file.
float	getFloat() Read one float field from the CSV file.
int	getInt() Read one integer field from the CSV file
int	getLineCount()
long	getLong() Read one long field from the CSV file
String[]	getRowNames()
static void	main(String[] args) Test driver
boolean	next()
void	readHeader(boolean lower)
void	skip(int fields) Skip over fields you don't want to process.
void	skipToNextLine() Skip over remaining fields on this line you don't want to process.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NO_QUOTS

public static final char NO_QUOTS

See Also:

Constant Field Values

Constructor Detail

CSVReader

public CSVReader(Reader r)

convenience Constructor, default to comma separator, " for quote, no multiline fields, with trimming.

Parameters:

r - input Reader source of CSV Fields to read.

CSVReader

public CSVReader(Reader r,
         char separator,
         char quote,
         boolean allowMultiLineFields,
         boolean trim)

Constructor

Parameters:

r - input Reader source of CSV Fields to read.

separator - field separator character, usually ',' in North America, ';' in Europe and sometimes '\t' for tab.

quote - char to use to enclose fields containing a separator, usually '\"'

allowMultiLineFields - true if reader should allow quoted fields to span more than one line. Microsoft Excel sometimes generates files like this.

trim - true if reader should trim lead/trailing whitespace e.g. blanks, Cr, Lf. Tab off fields.

Method Detail

close

public void close()
           throws IOException

Close the Reader.

Throws:

IOException

get

public String get()
           throws EOFException,
                  IOException

Read one field from the CSV file

Returns:

String value, even if the field is numeric. Surrounded and embedded double quotes are stripped. possibly "". null means end of line.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

getAllFieldsInLine

public String[] getAllFieldsInLine()
                            throws EOFException,
                                   IOException

Get all fields in the line

Returns:

Array of strings, one for each field. Possibly empty, but never null.

Throws:

EOFException

IOException

getDouble

public double getDouble()
                 throws EOFException,
                        IOException,
                        NumberFormatException

Read one double field from the CSV file.

Returns:

houble value, empty field returns 0, as does end of line.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

NumberFormatException - , if field does not contain a well-formed int.

getFloat

public float getFloat()
               throws EOFException,
                      IOException,
                      NumberFormatException

Read one float field from the CSV file.

Returns:

float value, empty field returns 0, as does end of line.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

NumberFormatException - , if field does not contain a well-formed int.

getInt

public int getInt()
           throws EOFException,
                  IOException,
                  NumberFormatException

Read one integer field from the CSV file

Returns:

int value, empty field returns 0, as does end of line.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

NumberFormatException - , if field does not contain a well-formed int.

getLong

public long getLong()
             throws EOFException,
                    IOException,
                    NumberFormatException

Read one long field from the CSV file

Returns:

long value, empty field returns 0, as does end of line.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

NumberFormatException - , if field does not contain a well-formed int.

skip

public void skip(int fields)
          throws EOFException,
                 IOException

Skip over fields you don't want to process.

Parameters:

fields - How many field you want to bypass reading. The newline counts as one field.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

skipToNextLine

public void skipToNextLine()
                    throws EOFException,
                           IOException

Skip over remaining fields on this line you don't want to process.

Throws:

EOFException - at end of file after all the fields have been read.

IOException - Some problem reading the file, possibly malformed data.

readHeader

public void readHeader(boolean lower)
                throws EOFException,
                       IOException

Throws:

EOFException

IOException

getRowNames

public String[] getRowNames()

next

public boolean next()
             throws IOException

Throws:

IOException

get

public String get(String row)
           throws IOException

Throws:

IOException

get

public String get(int row)

getLineCount

public int getLineCount()

main

public static void main(String[] args)

Test driver

Parameters:

args - not used