Class CsvOutput


  • public final class CsvOutput
    extends java.lang.Object
    Outputs a CSV formatted file.

    Provides a simple tool for writing a CSV file.

    Each line in the CSV file will consist of comma separated entries. Each entry may be quoted using a double quote. If an entry contains a double quote, comma or trimmable whitespace, it will be quoted. If an entry starts with '=' or '@', it will be quoted. Two double quotes will be used to escape a double quote.

    There are two modes of output. Standard mode provides the encoding described above which is accepted by most CSV parsers. Safe mode provides extra encoding to protect unsafe content from being run as a script in tools like Excel.

    Instances of this class contain mutable state. A new instance must be created for each file to be output.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static CsvOutput safe​(java.lang.Appendable underlying)
      Creates an instance, using the system default line separator and using a comma separator.
      static CsvOutput safe​(java.lang.Appendable underlying, java.lang.String newLine)
      Creates an instance, allowing the new line character to be controlled and using a comma separator.
      static CsvOutput safe​(java.lang.Appendable underlying, java.lang.String newLine, java.lang.String separator)
      Creates an instance, allowing the new line character to be controlled, specifying the separator.
      static CsvOutput standard​(java.lang.Appendable underlying)
      Creates an instance, using the system default line separator and using a comma separator.
      static CsvOutput standard​(java.lang.Appendable underlying, java.lang.String newLine)
      Creates an instance, allowing the new line character to be controlled and using a comma separator.
      static CsvOutput standard​(java.lang.Appendable underlying, java.lang.String newLine, java.lang.String separator)
      Creates an instance, allowing the new line character to be controlled, specifying the separator.
      CsvOutput writeCell​(java.lang.String cell)
      Writes a single cell to the current line, only quoting if needed.
      CsvOutput writeCell​(java.lang.String cell, boolean alwaysQuote)
      Writes a single cell to the current line.
      void writeLine​(java.util.List<java.lang.String> line)
      Writes a single CSV line to the underlying, only quoting if needed.
      void writeLine​(java.util.List<java.lang.String> line, boolean alwaysQuote)
      Writes a single CSV line to the underlying.
      void writeLines​(java.lang.Iterable<? extends java.util.List<java.lang.String>> lines, boolean alwaysQuote)
      Writes multiple CSV lines to the underlying.
      CsvOutput writeNewLine()
      Writes a new line character.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Method Detail

      • standard

        public static CsvOutput standard​(java.lang.Appendable underlying)
        Creates an instance, using the system default line separator and using a comma separator.

        See the standard quoting rules in the class-level documentation.

        Parameters:
        underlying - the destination to write to
        Returns:
        the CSV outputter
      • standard

        public static CsvOutput standard​(java.lang.Appendable underlying,
                                         java.lang.String newLine)
        Creates an instance, allowing the new line character to be controlled and using a comma separator.

        See the standard quoting rules in the class-level documentation.

        Parameters:
        underlying - the destination to write to
        newLine - the new line string
        Returns:
        the CSV outputter
      • standard

        public static CsvOutput standard​(java.lang.Appendable underlying,
                                         java.lang.String newLine,
                                         java.lang.String separator)
        Creates an instance, allowing the new line character to be controlled, specifying the separator.

        See the standard quoting rules in the class-level documentation.

        Parameters:
        underlying - the destination to write to
        newLine - the new line string
        separator - the separator used to separate each field, typically a comma, but a tab is sometimes used
        Returns:
        the CSV outputter
      • safe

        public static CsvOutput safe​(java.lang.Appendable underlying)
        Creates an instance, using the system default line separator and using a comma separator.

        This applies the standard quoting rules from the class-level documentation, plus an additional rule. If an entry starts with an expression character, '=', '@', '+' or '-', the entry will be quoted and the quote section will be preceeded by equals. Thus, the string '=Foo' will be written as '="=Foo"'. This avoids the string being treated as an expression by tools like Excel. Simple numbers are not quoted. Thus, the number '-1234' will still be written as '-1234'.

        Parameters:
        underlying - the destination to write to
        Returns:
        the CSV outputter
      • safe

        public static CsvOutput safe​(java.lang.Appendable underlying,
                                     java.lang.String newLine)
        Creates an instance, allowing the new line character to be controlled and using a comma separator.

        This applies the standard quoting rules from the class-level documentation, plus an additional rule. If an entry starts with an expression character, '=', '@', '+' or '-', the entry will be quoted and the quote section will be preceeded by equals. Thus, the string '=Foo' will be written as '="=Foo"'. This avoids the string being treated as an expression by tools like Excel. Simple numbers are not quoted. Thus, the number '-1234' will still be written as '-1234'.

        Parameters:
        underlying - the destination to write to
        newLine - the new line string
        Returns:
        the CSV outputter
      • safe

        public static CsvOutput safe​(java.lang.Appendable underlying,
                                     java.lang.String newLine,
                                     java.lang.String separator)
        Creates an instance, allowing the new line character to be controlled, specifying the separator.

        This applies the standard quoting rules from the class-level documentation, plus an additional rule. If an entry starts with an expression character, '=', '@', '+' or '-', the entry will be quoted and the quote section will be preceeded by equals. Thus, the string '=Foo' will be written as '="=Foo"'. This avoids the string being treated as an expression by tools like Excel. Simple numbers are not quoted. Thus, the number '-1234' will still be written as '-1234'.

        Parameters:
        underlying - the destination to write to
        newLine - the new line string
        separator - the separator used to separate each field, typically a comma, but a tab is sometimes used
        Returns:
        the CSV outputter
      • writeLines

        public void writeLines​(java.lang.Iterable<? extends java.util.List<java.lang.String>> lines,
                               boolean alwaysQuote)
        Writes multiple CSV lines to the underlying.

        The boolean flag controls whether each entry is always quoted or only quoted when necessary.

        Parameters:
        lines - the lines to write
        alwaysQuote - when true, each column will be quoted, when false, quoting is selective
        Throws:
        java.io.UncheckedIOException - if an IO exception occurs
      • writeLine

        public void writeLine​(java.util.List<java.lang.String> line)
        Writes a single CSV line to the underlying, only quoting if needed.

        This can be used as a method reference from a Stream pipeline from Stream.forEachOrdered(Consumer).

        This method writes each cell in the specified list to the underlying, followed by a new line character.

        Parameters:
        line - the line to write
        Throws:
        java.io.UncheckedIOException - if an IO exception occurs
      • writeLine

        public void writeLine​(java.util.List<java.lang.String> line,
                              boolean alwaysQuote)
        Writes a single CSV line to the underlying.

        The boolean flag controls whether each entry is always quoted or only quoted when necessary.

        This method writes each cell in the specified list to the underlying, followed by a new line character.

        Parameters:
        line - the line to write
        alwaysQuote - when true, each column will be quoted, when false, quoting is selective
        Throws:
        java.io.UncheckedIOException - if an IO exception occurs
      • writeCell

        public CsvOutput writeCell​(java.lang.String cell)
        Writes a single cell to the current line, only quoting if needed.

        When using this method, either writeNewLine() or one of the writeLine methods must be called at the end of the line.

        Parameters:
        cell - the cell to write
        Returns:
        this, for method chaining
        Throws:
        java.io.UncheckedIOException - if an IO exception occurs
      • writeCell

        public CsvOutput writeCell​(java.lang.String cell,
                                   boolean alwaysQuote)
        Writes a single cell to the current line.

        The boolean flag controls whether each entry is always quoted or only quoted when necessary.

        When using this method, either writeNewLine() or one of the writeLine methods must be called at the end of the line.

        Parameters:
        cell - the cell to write
        alwaysQuote - when true, the cell will be quoted, when false, quoting is selective
        Returns:
        this, for method chaining
        Throws:
        java.io.UncheckedIOException - if an IO exception occurs
      • writeNewLine

        public CsvOutput writeNewLine()
        Writes a new line character.
        Returns:
        this, for method chaining
        Throws:
        java.io.UncheckedIOException - if an IO exception occurs