Package com.Ostermiller.util

Class CSVParser

java.lang.Object
com.Ostermiller.util.CSVParser
All Implemented Interfaces:
CSVParse
public class CSVParser extends Object implements CSVParse
Read files in comma separated value format. More information about this class is available from ostermiller.org. CSV is a file format used as a portable representation of a database. Each line is one entry or record and the fields in a record are separated by commas. Commas may be preceded or followed by arbitrary space and/or tab characters which are ignored.

If field includes a comma or a new line, the whole field must be surrounded with double quotes. When the field is in quotes, any quote literals must be escaped by \" Backslash literals must be escaped by \\. Otherwise a backslash and the character following will be treated as the following character, IE. "\n" is equivalent to "n". Other escape sequences may be set using the setEscapes() method. Text that comes after quotes that have been closed but come before the next comma will be ignored.

Empty fields are returned as as String of length zero: "". The following line has three empty fields and three non-empty fields in it. There is an empty field on each end, and one in the middle. One token is returned as a space.

,second,," ",fifth,

Blank lines are always ignored. Other lines will be ignored if they start with a comment character as set by the setCommentStart() method.

An example of how CSVParser might be used: 

 CSVParser shredder = new CSVParser(System.in);
 shredder.setCommentStart("#;!");
 shredder.setEscapes("nrtf", "\n\r\t\f");
 String t;
 while ((t = shredder.nextValue()) != null){
     System.out.println("" + shredder.lastLineNumber() + " " + t);
 }

Many applications use the CSV formatted that Microsoft supports in Excel Spreadsheet. It is subtly different than the CSV format implemented by this class. It does not use backslash as an escape character, for example. For reading CSV for interoperability with Microsoft Excel or RFC 4180 use the com.Ostermiller.util.ExcelCSVParser class.

Since:
ostermillerutils 1.00.00
Author:
Stephen Ostermiller https://ostermiller.org/contact.pl?regarding=Java+Utilities
See Also:

  • Constructor Details

    • CSVParser

      public CSVParser(InputStream in)
      Create a parser to parse comma separated values from an InputStream.

      Byte to character conversion is done using the platform default locale.

      Parameters:
      in - stream that contains comma separated values.
      Since:
      ostermillerutils 1.00.00

    • CSVParser

      public CSVParser(InputStream in, char delimiter) throws BadDelimiterException
      Create a parser to parse delimited values from an InputStream.

      Byte to character conversion is done using the platform default locale.

      Parameters:
      in - stream that contains comma separated values.
      delimiter - record separator
      Throws:
      BadDelimiterException - if the specified delimiter cannot be used
      Since:
      ostermillerutils 1.02.24

    • CSVParser

      public CSVParser(Reader in)
      Create a parser to parse comma separated values from a Reader.
      Parameters:
      in - reader that contains comma separated values.
      Since:
      ostermillerutils 1.00.00

    • CSVParser

      public CSVParser(Reader in, char delimiter) throws BadDelimiterException
      Create a parser to parse delimited values from a Reader.
      Parameters:
      in - reader that contains comma separated values.
      delimiter - record separator
      Throws:
      BadDelimiterException - if the specified delimiter cannot be used
      Since:
      ostermillerutils 1.02.24

    • CSVParser

      public CSVParser(InputStream in, char delimiter, String escapes, String replacements, String commentDelims) throws BadDelimiterException
      Create a parser to parse delimited values from an InputStream.

      Byte to character conversion is done using the platform default locale.

      Parameters:
      in - stream that contains comma separated values.
      delimiter - record separator
      escapes - a list of characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Throws:
      BadDelimiterException - if the specified delimiter cannot be used
      Since:
      ostermillerutils 1.02.24

    • CSVParser

      public CSVParser(InputStream in, String escapes, String replacements, String commentDelims)
      Create a parser to parse comma separated values from an InputStream.

      Byte to character conversion is done using the platform default locale.

      Parameters:
      in - stream that contains comma separated values.
      escapes - a list of characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Since:
      ostermillerutils 1.00.00

    • CSVParser

      public CSVParser(Reader in, char delimiter, String escapes, String replacements, String commentDelims) throws BadDelimiterException
      Create a parser to parse delimited values from a Reader.
      Parameters:
      in - reader that contains comma separated values.
      delimiter - record separator
      escapes - a list of characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Throws:
      BadDelimiterException - if the specified delimiter cannot be used
      Since:
      ostermillerutils 1.02.24

    • CSVParser

      public CSVParser(Reader in, String escapes, String replacements, String commentDelims)
      Create a parser to parse comma separated values from a Reader.
      Parameters:
      in - reader that contains comma separated values.
      escapes - a list of characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Since:
      ostermillerutils 1.00.00

  • Method Details

    • close

      public void close() throws IOException
      Close any stream upon which this parser is based.
      Specified by:
      close in interface CSVParse
      Throws:
      IOException - if an error occurs while closing the stream.
      Since:
      ostermillerutils 1.02.22

    • nextValue

      public String nextValue() throws IOException
      get the next value.
      Specified by:
      nextValue in interface CSVParse
      Returns:
      the next value or null if there are no more values.
      Throws:
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.00.00

    • lastLineNumber

      public int lastLineNumber()
      Get the line number that the last token came from.

      New line breaks that occur in the middle of a token are no counted in the line number count.

      Specified by:
      lastLineNumber in interface CSVParse
      Returns:
      line number or -1 if no tokens have been returned yet.
      Since:
      ostermillerutils 1.00.00

    • getLine

      public String[] getLine() throws IOException
      Get all the values from a line.

      If the line has already been partially read, only the values that have not already been read will be included.

      Specified by:
      getLine in interface CSVParse
      Returns:
      all the values from the line or null if there are no more values.
      Throws:
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.00.00

    • getAllValues

      public String[][] getAllValues() throws IOException
      Get all the values from the file.

      If the file has already been partially read, only the values that have not already been read will be included.

      Each line of the file that has at least one value will be represented. Comments and empty lines are ignored.

      The resulting double array may be jagged.

      Specified by:
      getAllValues in interface CSVParse
      Returns:
      all the values from the file or null if there are no more values.
      Throws:
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.00.00

    • setEscapes

      public void setEscapes(String escapes, String replacements)
      Specify escape sequences and their replacements. Escape sequences set here are in addition to \\ and \". \\ and \" are always valid escape sequences. This method allows standard escape sequenced to be used. For example "\n" can be set to be a newline rather than an 'n'. A common way to call this method might be:
      setEscapes("nrtf", "\n\r\t\f");
      which would set the escape sequences to be the Java escape sequences. Characters that follow a \ that are not escape sequences will still be interpreted as that character.
      The two arguments to this method must be the same length. If they are not, the longer of the two will be truncated.
      Parameters:
      escapes - a list of characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      Since:
      ostermillerutils 1.00.00

    • changeDelimiter

      public void changeDelimiter(char newDelim) throws BadDelimiterException
      Change this parser so that it uses a new delimiter.

      The initial character is a comma, the delimiter cannot be changed to a quote or other character that has special meaning in CSV.

      Specified by:
      changeDelimiter in interface CSVParse
      Parameters:
      newDelim - delimiter to which to switch.
      Throws:
      BadDelimiterException - if the character cannot be used as a delimiter.
      Since:
      ostermillerutils 1.02.08

    • changeQuote

      public void changeQuote(char newQuote) throws BadQuoteException
      Change this parser so that it uses a new character for quoting.

      The initial character is a double quote ("), the delimiter cannot be changed to a comma or other character that has special meaning in CSV.

      Specified by:
      changeQuote in interface CSVParse
      Parameters:
      newQuote - character to use for quoting.
      Throws:
      BadQuoteException - if the character cannot be used as a quote.
      Since:
      ostermillerutils 1.02.16

    • setCommentStart

      public void setCommentStart(String commentDelims)
      Set the characters that indicate a comment at the beginning of the line. For example if the string "#;!" were passed in, all of the following lines would be comments:
       # Comment
 ; Another Comment
 ! Yet another comment
      By default there are no comments in CVS files. Commas and quotes may not be used to indicate comment lines.
      Parameters:
      commentDelims - list of characters a comment line may start with.
      Since:
      ostermillerutils 1.00.00

    • getLastLineNumber

      public int getLastLineNumber()
      Get the number of the line from which the last value was retrieved.
      Specified by:
      getLastLineNumber in interface CSVParse
      Returns:
      line number or -1 if no tokens have been returned.
      Since:
      ostermillerutils 1.00.00

    • parse

      public static String[][] parse(String s)
      Parse the comma delimited data from a string.

      Only escaped backslashes and quotes will be recognized as escape sequences. The data will be treated as having no comments.

      Parameters:
      s - string with comma delimited data to parse.
      Returns:
      parsed data.
      Since:
      ostermillerutils 1.02.03

    • parse

      public static String[][] parse(String s, char delimiter) throws BadDelimiterException
      Parse the delimited data from a string.

      Only escaped backslashes and quotes will be recognized as escape sequences. The data will be treated as having no comments.

      Parameters:
      s - string with delimited data to parse.
      delimiter - record separator
      Returns:
      parsed data.
      Throws:
      BadDelimiterException - if the character cannot be used as a delimiter.
      Since:
      ostermillerutils 1.02.24

    • parse

      public static String[][] parse(String s, String escapes, String replacements, String commentDelims)
      Parse the comma delimited data from a string. Escaped backslashes and quotes will always recognized as escape sequences.
      Parameters:
      s - string with comma delimited data to parse.
      escapes - a list of additional characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Returns:
      parsed data.
      Since:
      ostermillerutils 1.02.03

    • parse

      public static String[][] parse(String s, char delimiter, String escapes, String replacements, String commentDelims) throws BadDelimiterException
      Parse the delimited data from a string. Escaped backslashes and quotes will always recognized as escape sequences.
      Parameters:
      s - string with delimited data to parse.
      delimiter - record separator
      escapes - a list of additional characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Returns:
      parsed data.
      Throws:
      BadDelimiterException - if the character cannot be used as a delimiter.
      Since:
      ostermillerutils 1.02.24

    • parse

      public static String[][] parse(Reader in, char delimiter) throws IOException, BadDelimiterException
      Parse the comma delimited data from a stream.

      Only escaped backslashes and quotes will be recognized as escape sequences. The data will be treated as having no comments.

      Parameters:
      in - Reader with comma delimited data to parse.
      delimiter - record separator
      Returns:
      parsed data.
      Throws:
      BadDelimiterException - if the character cannot be used as a delimiter.
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.02.24

    • parse

      public static String[][] parse(Reader in) throws IOException
      Parse the delimited data from a stream.

      Only escaped backslashes and quotes will be recognized as escape sequences. The data will be treated as having no comments.

      Parameters:
      in - Reader with comma delimited data to parse.
      Returns:
      parsed data.
      Throws:
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.02.03

    • parse

      public static String[][] parse(Reader in, char delimiter, String escapes, String replacements, String commentDelims) throws IOException, BadDelimiterException
      Parse the delimited data from a stream. Escaped backslashes and quotes will always recognized as escape sequences.
      Parameters:
      in - Reader with delimited data to parse.
      delimiter - record separator
      escapes - a list of additional characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Returns:
      parsed data.
      Throws:
      BadDelimiterException - if the character cannot be used as a delimiter.
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.02.24

    • parse

      public static String[][] parse(Reader in, String escapes, String replacements, String commentDelims) throws IOException
      Parse the comma delimited data from a stream. Escaped backslashes and quotes will always recognized as escape sequences.
      Parameters:
      in - Reader with comma delimited data to parse.
      escapes - a list of additional characters that will represent escape sequences.
      replacements - the list of replacement characters for those escape sequences.
      commentDelims - list of characters a comment line may start with.
      Returns:
      parsed data.
      Throws:
      IOException - if an error occurs while reading.
      Since:
      ostermillerutils 1.02.03