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<?xml version="1.0" encoding="UTF-8"?>
<faqs xmlns="http://maven.apache.org/FML/1.0.1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/FML/1.0.1 http://maven.apache.org/xsd/fml-1.0.1.xsd"
title="Frequently Asked Questions"
toplink="false">
<part id="general">
<title>General</title>
<faq id="what-is-opencsv">
<question>What is opencsv?</question>
<answer>
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.
</answer>
</faq>
<faq id="where-can-I-get-it">
<question>Where can I get it?</question>
<answer>
Source and binaries are available from
<a href="http://www.sf.net/projects/opencsv">Sourceforge</a>. You can check out
the <a href="apidocs/index.html">javadocs</a> online.
</answer></faq>
<faq id="what-features">
<question>What features does opencsv support?</question>
<answer>
opencsv supports all the basic csv-type things you're likely to want to do:
<ul>
<li>Arbitrary numbers of values per line</li>
<li>Ignoring commas in quoted elements</li>
<li>Handling quoted entries with embedded carriage returns (ie entries
that span multiple lines)</li>
<li>Configurable separator and quote characters (or use sensible defaults)</li>
<li>Read all the entries at once, or use an Iterator style model</li>
<li>Creating csv files from String[] (ie. automatic escaping of embedded quote chars)</li>
</ul>
</answer></faq>
</part>
<part id="reading-and-writing">
<title>Reading and Writing</title>
<faq id="how-to-read">
<question>How do I read and parse a CSV file?</question>
<answer>
If you want to use an Iterator style pattern, you might do something like
this:
<source>
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...");
}
</source>
Or, if you might just want to slurp the whole lot into a <code>List</code>, just call
<code>readAll()</code>...
<source>
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
List myEntries = reader.readAll();
</source>
which will give you a <code>List</code> of <code>String[]</code> that you
can iterate over. If all else fails, check out the <a href="apidocs/index.html">Javadoc</a>.
</answer></faq>
<faq id="custom-sepators"><question>Can I use my own separators and quote characters?</question>
<answer>
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:
<source>
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"), '\t');
</source>
And if you single quoted your escaped characters rather than double
quote them, you can use the three arg constructor:
<source>
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"), '\t', '\'');
</source>
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:
<source>
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"), '\t', '\'', 2);
</source>
</answer></faq>
<faq id="can-I-write"><question>Can I write csv files with opencsv?</question>
<answer>
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:
<source>
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();
</source>
<p/>
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).
<p/>
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.
</answer></faq>
<faq id="sql-integration"><question>Can I dump out SQL tables to CSV?</question>
<answer>
Yes you can. Sean Sullivan added a neat feature to CSVWriter so you
can pass <code>writeAll()</code> a ResultSet.
<source>
java.sql.ResultSet myResultSet = ....
writer.writeAll(myResultSet, includeHeaders);
</source>
</answer></faq>
<faq id="javabean-integration"><question>Is there a way to bind my CSV file to a list of Javabeans?</question>
<answer>
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 <code>au.com.bytecode.opencsv.bean</code> package.
Here's how you can map to a java bean based on
the field positions in your CSV file:
<source>
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);
</source>
For more detailed examples, check out the test cases for each of the available
mapping strategies under the /test/au/com/bytecode/opencsv/bean/.
</answer></faq>
</part>
<part id="other">
<title>Other Stuff</title>
<faq id="using-commercially"><question>Can I use opencsv in my commercial applications?</question>
<answer>
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 <a
href="http://www.apache.org/licenses/LICENSE-2.0">Apache 2.0
license agreement</a>.
</answer></faq>
<faq id="getting-the-source"><question>Can I get the source? More example code?</question>
<answer>
Yes. The download from the SourceForge page includes the full source in the
<code>/src</code> directory. It's just a few files, so go crazy. There is also a
sample addressbook csv reader in the <code>/examples</code> directory.
And for extra marks, there's a JUnit test suite in the <code>/test</code>
directory.
</answer></faq>
<faq id="maven-integration"><question>How can I use it in my Maven projects?</question>
<answer>
Add a dependency element to your pom:
<source>
<dependency>
<groupId>net.sf.opencsv</groupId>
<artifactId>opencsv</artifactId>
<version>2.0</version>
</dependency>
</source>
</answer></faq>
<faq id="who-maintains"><question>Who maintains opencsv?</question>
<answer>
opencsv was developed in a couple of hours by Glen Smith. You can read his <a
href="http://blogs.bytecode.com.au/glen">blog</a> for more info
and contact details. Kyle Miller contributed the bean binding work,
Scott Conway has done tons of bug fixing, and Sean Sullivan is the current maintainer
of the project.
<p/>
If you've found a bug, you can report it on the <a
href="http://www.sf.net/projects/opencsv">project page</a> at
Sourceforge. Please post a sample file that demonstrates your issue.
For bonus marks, post a patch too. :-)
</answer></faq>
</part>
<part id="developerStuff">
<title>opencsv Development Stuff</title>
<faq id="where-is-the-snapshot-repo">
<question>Is there a snapshot Maven repo for opencsv?</question>
<answer>Yes. We're using a <a href="http://oss.sonatype.org/content/groups/sourceforge/net/sf/opencsv/opencsv/">repo</a> provided by the good folk at Sonatype.
</answer>
</faq>
</part>
</faqs>