opencsv

opencsv - Frequently Asked Questions

Reading and Writing

1. How do I read and parse a CSV file?
2. Can I use my own separators and quote characters?
3. Can I write csv files with opencsv?
4. Can I dump out SQL tables to CSV?
5. Is there a way to bind my CSV file to a list of Javabeans?

Other Stuff

1. Can I use opencsv in my commercial applications?
2. Can I get the source? More example code?
3. How can I use it in my Maven projects?
4. Who maintains opencsv?

opencsv Development Stuff

1. Is there a snapshot Maven repo for opencsv?
2. I'm an opencsv developer, how do you go about releasing a new version?

General

What is opencsv?

opencsv is a very simple csv (comma-separated values) parser library for
Java. It was developed because all of current csv parsers I've come across
don't have commercial-friendly licenses.

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Where can I get it?

Source and binaries are available from
Sourceforge. You can check out
the javadocs online.

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What features does opencsv support?

opencsv supports all the basic csv-type things you're likely to want to do:

• Arbitrary numbers of values per line
• Ignoring commas in quoted elements
• Handling quoted entries with embedded carriage returns (ie entries
  that span multiple lines)
• Configurable separator and quote characters (or use sensible defaults)
• Read all the entries at once, or use an Iterator style model
• Creating csv files from String[] (ie. automatic escaping of embedded quote chars)

Reading and Writing

How do I read and parse a CSV file?

If you want to use an Iterator style pattern, you might do something like
this:

    CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
    String [] nextLine;
    while ((nextLine = reader.readNext()) != null) {
        // nextLine[] is an array of values from the line
        System.out.println(nextLine[0] + nextLine[1] + "etc...");
    }
           

Or, if you might just want to slurp the whole lot into a List, just call
readAll()...

    CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
    List myEntries = reader.readAll();
           

which will give you a List of String[] that you
can iterate over. If all else fails, check out the Javadoc.

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Can I use my own separators and quote characters?

Yes. There are constructors that cater for supplying your own
separator and quote characters. Say you're using a tab for your
separator, you can do something like this:

    CSVReader reader = new CSVReader(new FileReader("yourfile.csv"), '\t');
               

And if you single quoted your escaped characters rather than double
quote them, you can use the three arg constructor:

    CSVReader reader = new CSVReader(new FileReader("yourfile.csv"), '\t', '\'');
           

You may also skip the first few lines of the file if you know that
the content doesn't start till later in the file. So, for example,
you can skip the first two lines by doing:

    CSVReader reader = new CSVReader(new FileReader("yourfile.csv"), '\t', '\'', 2);
           

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Can I write csv files with opencsv?

Yes. There is a CSVWriter in the same package that follows the same
semantics as the CSVReader. For example, to write a tab separated file:

     CSVWriter writer = new CSVWriter(new FileWriter("yourfile.csv"), '\t');
     // feed in your array (or convert your data to an array)
     String[] entries = "first#second#third".split("#");
     writer.writeNext(entries);
	writer.close();
               

If you'd prefer to use your own quote characters, you may use the
three arg version of the constructor, which takes a quote
character (or feel free to pass in CSVWriter.NO_QUOTE_CHARACTER).

You can also customise the line terminators used in the generated
file (which is handy when you're exporting from your Linux web
application to Windows clients). There is a constructor argument
for this purpose.

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Can I dump out SQL tables to CSV?

Yes you can. Sean Sullivan added a neat feature to CSVWriter so you
can pass writeAll() a ResultSet.

java.sql.ResultSet myResultSet = ....
writer.writeAll(myResultSet, includeHeaders);
           

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Is there a way to bind my CSV file to a list of Javabeans?

Yes there is. Kyle Miller added a new set of classes to allow you to bind
a CSV file to a list of JavaBeans based on column name, column position, or a
custom mapping strategy. You can find the new classes in
the au.com.bytecode.opencsv.bean package.
Here's how you can map to a java bean based on
the field positions in your CSV file:

ColumnPositionMappingStrategy strat = new ColumnPositionMappingStrategy();
strat.setType(YourOrderBean.class);
String[] columns = new String[] {"name", "orderNumber", "id"}; // the fields to bind do in your JavaBean
strat.setColumnMapping(columns);

CsvToBean csv = new CsvToBean();
List list = csv.parse(strat, yourReader);
           

For more detailed examples, check out the test cases for each of the available
mapping strategies under the /test/au/com/bytecode/opencsv/bean/.

Other Stuff

Can I use opencsv in my commercial applications?

Yes. opencsv is available under a commercial-friendly Apache 2.0 license.
You are free to include it in your commericial applications without any fee
or charge, and you are free to modify it to suit your circumstances. To find
out more details of the license, read the Apache 2.0
license agreement.

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Can I get the source? More example code?

Yes. The download from the SourceForge page includes the full source in the
/src directory. It's just a few files, so go crazy. There is also a
sample addressbook csv reader in the /examples directory.
And for extra marks, there's a JUnit test suite in the /test
directory.

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How can I use it in my Maven projects?

Add a dependency element to your pom:

<dependency>
	<groupId>net.sf.opencsv</groupId>
	<artifactId>opencsv</artifactId>
	<version>2.0</version>
</dependency>