This page contains some examples of writing CSV files using Super CSV. You can view the full source of the examples here. For examples of writing CSV files with Dozer (using CsvDozerBeanWriter), click here.
All of the examples on this page use the following cell processor configuration.
It demonstrates:
Don't forget that you can write your own cell processors if you want!
/**
* Sets up the processors used for the examples. There are 10 CSV columns, so 10 processors are defined. All values
* are converted to Strings before writing (there's no need to convert them), and null values will be written as
* empty columns (no need to convert them to "").
*
* @return the cell processors
*/
private static CellProcessor[] getProcessors() {
final CellProcessor[] processors = new CellProcessor[] {
new UniqueHashCode(), // customerNo (must be unique)
new NotNull(), // firstName
new NotNull(), // lastName
new FmtDate("dd/MM/yyyy"), // birthDate
new NotNull(), // mailingAddress
new Optional(new FmtBool("Y", "N")), // married
new Optional(), // numberOfKids
new NotNull(), // favouriteQuote
new NotNull(), // email
new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
};
return processors;
}CsvBeanWriter is the easiest writer to work with. The example writes a List of CustomerBeans (which extend from PersonBean) to a CSV file.
This relies on the fact that the bean's field names match up exactly with the column names in the header of the CSV file
customerNo,firstName,lastName,birthDate,mailingAddress,married,numberOfKids,favouriteQuote,email,loyaltyPoints
and the bean has the appropriate getters defined for each field.
If your header doesn't match (the column names have spaces, for example), then you can simply define your own name mapping array that does match the field names.
Note that the cell processors are compatible with their associated field types in the bean (e.g. birthDate is a java.util.Date in the bean, and uses the FmtDate cell processor).
/**
* An example of writing using CsvBeanWriter.
*/
private static void writeWithCsvBeanWriter() throws Exception {
// create the customer beans
final CustomerBean john = new CustomerBean("1", "John", "Dunbar",
new GregorianCalendar(1945, Calendar.JUNE, 13).getTime(),
"1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States", null, null,
"\"May the Force be with you.\" - Star Wars", "jdunbar@gmail.com", 0L);
final CustomerBean bob = new CustomerBean("2", "Bob", "Down",
new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime(),
"1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States", true, 0,
"\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind", "bobdown@hotmail.com", 123456L);
final List<CustomerBean> customers = Arrays.asList(john, bob);
ICsvBeanWriter beanWriter = null;
try {
beanWriter = new CsvBeanWriter(new FileWriter("target/writeWithCsvBeanWriter.csv"),
CsvPreference.STANDARD_PREFERENCE);
// the header elements are used to map the bean values to each column (names must match)
final String[] header = new String[] { "customerNo", "firstName", "lastName", "birthDate",
"mailingAddress", "married", "numberOfKids", "favouriteQuote", "email", "loyaltyPoints" };
final CellProcessor[] processors = getProcessors();
// write the header
beanWriter.writeHeader(header);
// write the beans
for( final CustomerBean customer : customers ) {
beanWriter.write(customer, header, processors);
}
}
finally {
if( beanWriter != null ) {
beanWriter.close();
}
}
}Output:
customerNo,firstName,lastName,birthDate,mailingAddress,married,numberOfKids,favouriteQuote,email,loyaltyPoints 1,John,Dunbar,13/06/1945,"1600 Amphitheatre Parkway Mountain View, CA 94043 United States",,,"""May the Force be with you."" - Star Wars",jdunbar@gmail.com,0 2,Bob,Down,25/02/1919,"1601 Willow Rd. Menlo Park, CA 94025 United States",Y,0,"""Frankly, my dear, I don't give a damn."" - Gone With The Wind",bobdown@hotmail.com,123456
CsvListWriter is the most primitive writer and should only be used if it's not possible to use the other implementations.
On the other hand, it is the only writer that can be used for writing CSV files with an arbitrary number of columns (which is not technically valid CSV, but still happens), and it's a quick and dirty way to write CSV from a List or array of Strings.
/**
* An example of reading using CsvListWriter.
*/
private static void writeWithCsvListWriter() throws Exception {
// create the customer Lists (CsvListWriter also accepts arrays!)
final List<Object> john = Arrays.asList(new Object[] { "1", "John", "Dunbar",
new GregorianCalendar(1945, Calendar.JUNE, 13).getTime(),
"1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States", null, null,
"\"May the Force be with you.\" - Star Wars", "jdunbar@gmail.com", 0L });
final List<Object> bob = Arrays.asList(new Object[] { "2", "Bob", "Down",
new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime(),
"1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States", true, 0,
"\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind", "bobdown@hotmail.com", 123456L });
ICsvListWriter listWriter = null;
try {
listWriter = new CsvListWriter(new FileWriter("target/writeWithCsvListWriter.csv"),
CsvPreference.STANDARD_PREFERENCE);
final CellProcessor[] processors = getProcessors();
final String[] header = new String[] { "customerNo", "firstName", "lastName", "birthDate",
"mailingAddress", "married", "numberOfKids", "favouriteQuote", "email", "loyaltyPoints" };
// write the header
listWriter.writeHeader(header);
// write the customer lists
listWriter.write(john, processors);
listWriter.write(bob, processors);
}
finally {
if( listWriter != null ) {
listWriter.close();
}
}
}Output:
customerNo,firstName,lastName,birthDate,mailingAddress,married,numberOfKids,favouriteQuote,email,loyaltyPoints 1,John,Dunbar,13/06/1945,"1600 Amphitheatre Parkway Mountain View, CA 94043 United States",,,"""May the Force be with you."" - Star Wars",jdunbar@gmail.com,0 2,Bob,Down,25/02/1919,"1601 Willow Rd. Menlo Park, CA 94025 United States",Y,0,"""Frankly, my dear, I don't give a damn."" - Gone With The Wind",bobdown@hotmail.com,123456
CsvMapWriter is a good compromise if you can't use CsvBeanWriter.
/**
* An example of reading using CsvMapWriter.
*/
private static void writeWithCsvMapWriter() throws Exception {
final String[] header = new String[] { "customerNo", "firstName", "lastName", "birthDate", "mailingAddress",
"married", "numberOfKids", "favouriteQuote", "email", "loyaltyPoints" };
// create the customer Maps (using the header elements for the column keys)
final Map<String, Object> john = new HashMap<String, Object>();
john.put(header[0], "1");
john.put(header[1], "John");
john.put(header[2], "Dunbar");
john.put(header[3], new GregorianCalendar(1945, Calendar.JUNE, 13).getTime());
john.put(header[4], "1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States");
john.put(header[5], null);
john.put(header[6], null);
john.put(header[7], "\"May the Force be with you.\" - Star Wars");
john.put(header[8], "jdunbar@gmail.com");
john.put(header[9], 0L);
final Map<String, Object> bob = new HashMap<String, Object>();
bob.put(header[0], "2");
bob.put(header[1], "Bob");
bob.put(header[2], "Down");
bob.put(header[3], new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime());
bob.put(header[4], "1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States");
bob.put(header[5], true);
bob.put(header[6], 0);
bob.put(header[7], "\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind");
bob.put(header[8], "bobdown@hotmail.com");
bob.put(header[9], 123456L);
ICsvMapWriter mapWriter = null;
try {
mapWriter = new CsvMapWriter(new FileWriter("target/writeWithCsvMapWriter.csv"),
CsvPreference.STANDARD_PREFERENCE);
final CellProcessor[] processors = getProcessors();
// write the header
mapWriter.writeHeader(header);
// write the customer maps
mapWriter.write(john, header, processors);
mapWriter.write(bob, header, processors);
}
finally {
if( mapWriter != null ) {
mapWriter.close();
}
}
}Output:
customerNo,firstName,lastName,birthDate,mailingAddress,married,numberOfKids,favouriteQuote,email,loyaltyPoints 1,John,Dunbar,13/06/1945,"1600 Amphitheatre Parkway Mountain View, CA 94043 United States",,,"""May the Force be with you."" - Star Wars",jdunbar@gmail.com,0 2,Bob,Down,25/02/1919,"1601 Willow Rd. Menlo Park, CA 94025 United States",Y,0,"""Frankly, my dear, I don't give a damn."" - Gone With The Wind",bobdown@hotmail.com,123456