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.

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

Modifier and Type	Method and Description
void	close() Closes resources.
long	getCurrentLineNumber() Returns the current line number in the input stream.
String	getFirstEndOfLine() Gets the first end-of-line string encountered.
Map<String,Integer>	getHeaderMap() Returns a copy of the header map.
List<String>	getHeaderNames() Returns a read-only list of header names 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(InputStream inputStream, Charset charset, CSVFormat format) Creates a CSV parser using the given CSVFormat.
static CSVParser	parse(Path path, Charset charset, CSVFormat format) Creates a parser for the given Path.
static CSVParser	parse(Reader reader, CSVFormat format) Creates a CSV parser using the given CSVFormat
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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

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.

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(InputStream inputStream,
                              Charset charset,
                              CSVFormat format)
                       throws IOException

Creates a 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:

inputStream - an InputStream containing CSV-formatted input. Must not be null.

charset - a Charset.

format - the CSVFormat used for CSV parsing. Must not be null.

Returns:

a new CSVParser configured with the given reader and format.

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:

1.5

parse

public static CSVParser parse(Path path,
                              Charset charset,
                              CSVFormat format)
                       throws IOException

Creates a parser for the given Path.

Parameters:

path - 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

Since:

1.5

parse

public static CSVParser parse(Reader reader,
                              CSVFormat format)
                       throws IOException

Creates a 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.

Returns:

a new CSVParser configured with the given reader and format.

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:

1.5

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

getFirstEndOfLine

public String getFirstEndOfLine()

Gets the first end-of-line string encountered.

Returns:

the first end-of-line string

Since:

1.5

getHeaderMap

public Map<String,Integer> getHeaderMap()

Returns a copy of the header map.

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

Returns:

a copy of the header map.

getHeaderNames

public List<String> getHeaderNames()

Returns a read-only list of header names that iterates in column order.

Returns:

read-only list of header names that iterates in column order.

Since:

1.7

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.

An IOException caught during the iteration are re-thrown as an IllegalStateException.

If the parser is closed a call to Iterator.next() will throw a NoSuchElementException.

Specified by:

iterator in interface Iterable<CSVRecord>