# CSVParser (Apache Commons CSV 1.2 API)

org.apache.commons.csv

## Class CSVParser

- java.lang.Object
- - org.apache.commons.csv.CSVParser

- All Implemented Interfaces:
    Closeable, AutoCloseable, Iterable<CSVRecord>

      public final class CSVParser
      extends Object
      implements Iterable<CSVRecord>, Closeable

  Parses CSV files according to the specified format. Because CSV appears in many different dialects, the parser supports many formats by allowing the specification of a `CSVFormat`. The parser works record wise. It is not possible to go back, once a record has been parsed from the input stream.

  ## Creating instances

  There are several static factory methods that can be used to create instances for various types of resources:

  - `parse(java.io.File, Charset, CSVFormat)`
  - `parse(String, CSVFormat)`
  - `parse(java.net.URL, java.nio.charset.Charset, CSVFormat)`

  Alternatively parsers can also be created by passing a `Reader` directly to the sole constructor. For those who like fluent APIs, parsers can be created using `CSVFormat.parse(java.io.Reader)` as a shortcut:

       for(CSVRecord record : CSVFormat.EXCEL.parse(in)) {
           ...
       }

  ## Parsing record wise

  To parse a CSV input from a file, you write:

       File csvData = new File("/path/to/csv");
       CSVParser parser = CSVParser.parse(csvData, CSVFormat.RFC4180);
       for (CSVRecord csvRecord : parser) {
           ...
       }

  This will read the parse the contents of the file using the RFC 4180 format.

  To parse CSV input in a format like Excel, you write:

       CSVParser parser = CSVParser.parse(csvData, CSVFormat.EXCEL);
       for (CSVRecord csvRecord : parser) {
           ...
       }

  If the predefined formats don't match the format at hands, custom formats can be defined. More information about customising CSVFormats is available in `CSVFormat JavaDoc`.

  ## Parsing into memory

  If parsing record wise is not desired, the contents of the input can be read completely into memory.

       Reader in = new StringReader("a;b\nc;d");
       CSVParser parser = new CSVParser(in, CSVFormat.EXCEL);
       List<CSVRecord> list = parser.getRecords();

  There are two constraints that have to be kept in mind:

  1. Parsing into memory starts at the current position of the parser. If you have already parsed records from the input, those records will not end up in the in memory representation of your CSV data.
  2. Parsing into memory may consume a lot of system resources depending on the input. For example if you're parsing a 150MB file of CSV data the contents will be read completely into memory.

  ## Notes

  Internal parser state is completely covered by the format and the reader-state.

  Version:
    $Id: CSVParser.java 1695167 2015-08-10 21:08:58Z ggregory $
  See Also:
    package documentation for more details

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `CSVParser(Reader reader, CSVFormat format)` Customized CSV parser using the given `CSVFormat`
    `CSVParser(Reader reader, CSVFormat format, long characterOffset, long recordNumber)` Customized CSV parser using the given `CSVFormat`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `close()` Closes resources.
    `long` | `getCurrentLineNumber()` Returns the current line number in the input stream.
    `Map<String,Integer>` | `getHeaderMap()` Returns a copy of the header map that iterates in column order.
    `long` | `getRecordNumber()` Returns the current record number in the input stream.
    `List<CSVRecord>` | `getRecords()` Parses the CSV input according to the given format and returns the content as a list of `CSVRecords`.
    `boolean` | `isClosed()` Gets whether this parser is closed.
    `Iterator<CSVRecord>` | `iterator()` Returns an iterator on the records.
    `static CSVParser` | `parse(File file, Charset charset, CSVFormat format)` Creates a parser for the given `File`.
    `static CSVParser` | `parse(String string, CSVFormat format)` Creates a parser for the given `String`.
    `static CSVParser` | `parse(URL url, Charset charset, CSVFormat format)` Creates a parser for the given URL.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### CSVParser

          public CSVParser(Reader reader,
                   CSVFormat format)
                    throws IOException

      Customized CSV parser using the given `CSVFormat`

      If you do not read all records from the given `reader`, you should call `close()` on the parser, unless you close the `reader`.

      Parameters:
        `reader` - a Reader containing CSV-formatted input. Must not be null.
        `format` - the CSVFormat used for CSV parsing. Must not be null.
      Throws:
        `IllegalArgumentException` - If the parameters of the format are inconsistent or if either reader or format are null.
        `IOException` - If there is a problem reading the header or skipping the first record

    - #### CSVParser

          public CSVParser(Reader reader,
                   CSVFormat format,
                   long characterOffset,
                   long recordNumber)
                    throws IOException

      Customized CSV parser using the given `CSVFormat`

      If you do not read all records from the given `reader`, you should call `close()` on the parser, unless you close the `reader`.

      Parameters:
        `reader` - a Reader containing CSV-formatted input. Must not be null.
        `format` - the CSVFormat used for CSV parsing. Must not be null.
        `characterOffset` - Lexer offset when the parser does not start parsing at the beginning of the source.
        `recordNumber` - The next record number to assign
      Throws:
        `IllegalArgumentException` - If the parameters of the format are inconsistent or if either reader or format are null.
        `IOException` - If there is a problem reading the header or skipping the first record
      Since:
        1.1

  - ### Method Detail

    - #### parse

          public static CSVParser parse(File file,
                        Charset charset,
                        CSVFormat format)
                                 throws IOException

      Creates a parser for the given `File`.

      Note: This method internally creates a FileReader using `FileReader.FileReader(java.io.File)` which in turn relies on the default encoding of the JVM that is executing the code. If this is insufficient create a URL to the file and use `parse(URL, Charset, CSVFormat)`

      Parameters:
        `file` - a CSV file. Must not be null.
        `charset` - A charset
        `format` - the CSVFormat used for CSV parsing. Must not be null.
      Returns:
        a new parser
      Throws:
        `IllegalArgumentException` - If the parameters of the format are inconsistent or if either file or format are null.
        `IOException` - If an I/O error occurs

    - #### parse

          public static CSVParser parse(String string,
                        CSVFormat format)
                                 throws IOException

      Creates a parser for the given `String`.
      Parameters:
        `string` - a CSV string. Must not be null.
        `format` - the CSVFormat used for CSV parsing. Must not be null.
      Returns:
        a new parser
      Throws:
        `IllegalArgumentException` - If the parameters of the format are inconsistent or if either string or format are null.
        `IOException` - If an I/O error occurs

    - #### parse

          public static CSVParser parse(URL url,
                        Charset charset,
                        CSVFormat format)
                                 throws IOException

      Creates a parser for the given URL.

      If you do not read all records from the given `url`, you should call `close()` on the parser, unless you close the `url`.

      Parameters:
        `url` - a URL. Must not be null.
        `charset` - the charset for the resource. Must not be null.
        `format` - the CSVFormat used for CSV parsing. Must not be null.
      Returns:
        a new parser
      Throws:
        `IllegalArgumentException` - If the parameters of the format are inconsistent or if either url, charset or format are null.
        `IOException` - If an I/O error occurs

    - #### close

          public void close()
                     throws IOException

      Closes resources.
      Specified by:
        `close` in interface `Closeable`
      Specified by:
        `close` in interface `AutoCloseable`
      Throws:
        `IOException` - If an I/O error occurs

    - #### getCurrentLineNumber

          public long getCurrentLineNumber()

      Returns the current line number in the input stream.

      ATTENTION: If your CSV input has multi-line values, the returned number does not correspond to the record number.

      Returns:
        current line number

    - #### getHeaderMap

          public Map<String,Integer> getHeaderMap()

      Returns a copy of the header map that iterates in column order.

      The map keys are column names. The map values are 0-based indices.

      Returns:
        a copy of the header map that iterates in column order.

    - #### getRecordNumber

          public long getRecordNumber()

      Returns the current record number in the input stream.

      ATTENTION: If your CSV input has multi-line values, the returned number does not correspond to the line number.

      Returns:
        current record number

    - #### getRecords

          public List<CSVRecord> getRecords()
                                     throws IOException

      Parses the CSV input according to the given format and returns the content as a list of `CSVRecords`.

      The returned content starts at the current parse-position in the stream.

      Returns:
        list of `CSVRecords`, may be empty
      Throws:
        `IOException` - on parse error or input read-failure

    - #### isClosed

          public boolean isClosed()

      Gets whether this parser is closed.
      Returns:
        whether this parser is closed.

    - #### iterator

          public Iterator<CSVRecord> iterator()

      Returns an iterator on the records.

      IOExceptions occurring during the iteration are wrapped in a RuntimeException. If the parser is closed a call to `next()` will throw a NoSuchElementException.

      Specified by:
        `iterator` in interface `Iterable<CSVRecord>`

Copyright © 2015 The Apache Software Foundation. All rights reserved.