CSV API for Java

Question

Can anyone recommend a simple API that will allow me to use read a CSV input file  do some simple transformations  and then write it   A quick google has found http   flatpack sourceforge net  which looks promising   I just wanted to check what others are using before I couple myself to this API

User · Answer

I ve used OpenCSV in the past    import au com bytecode opencsv CSVReader   String fileName    data csv   CSVReader reader   new CSVReader new FileReader fileName         if the first line is the header String   header   reader readNext       iterate over reader readNext until it returns null String   line   reader readNext      There were some other choices in the answers to another question

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Reading CSV format description makes me feel that using 3rd party library would be less headache than writing it myself    http   en wikipedia org wiki Comma-separated values   Wikipedia lists 10 or something known libraries    http   en wikipedia org wiki CSV application support   I compared libs listed using some kind of check list  OpenCSV turned out a winner to me  YMMV  with the following results     maven    maven - release version      had some cryptic issues at  Hudson  with snapshot references   gt  prefer to be on a safe side    code examples    open source      as in  can hack myself if needed     understandable javadoc      as opposed to eg javadocs of  genjava gj-csv     compact API      YAGNI  note  flatpack  seems to have much richer API than OpenCSV   - reference to specification used      I really like it when people can explain what they re doing  - reference to  RFC 4180  support      would qualify as simplest form of specification to me  - releases changelog      absence is quite a pity  given how simple it d be to get with maven-changes-plugin       flatpack   for comparison  has quite helpful changelog    bug tracking    active      as in  can submit a bug and expect a fixed release soon     positive feedback      Recommended By 51 users at sourceforge  as of now

User · Answer

The CSV format sounds easy enough for StringTokenizer but it can become more complicated  Here in Germany a semicolon is used as a delimiter and cells containing delimiters need to be escaped  You re not going to handle that easily with StringTokenizer   I would go for http   sourceforge net projects javacsv

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Apache Commons CSV  Check out Apache Common CSV   This library reads and writes several variations of CSV  including the standard one RFC 4180  Also reads writes Tab-delimited files    Excel  InformixUnload  InformixUnloadCsv  MySQL  Oracle  PostgreSQLCsv  PostgreSQLText  RFC4180  TDF

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You can use csvreader api  amp  download from following location   http   sourceforge net projects javacsv files JavaCsv JavaCsv 202 1 javacsv2 1 zip download  or  http   sourceforge net projects javacsv   Use the following code                  For Reading                   import java io FileNotFoundException  import java io IOException   import com csvreader CsvReader   public class CsvReaderExample        public static void main String   args            try                CsvReader products   new CsvReader  products csv                 products readHeaders                 while  products readRecord                                  String productID   products get  ProductID                    String productName   products get  ProductName                    String supplierID   products get  SupplierID                    String categoryID   products get  CategoryID                    String quantityPerUnit   products get  QuantityPerUnit                    String unitPrice   products get  UnitPrice                    String unitsInStock   products get  UnitsInStock                    String unitsOnOrder   products get  UnitsOnOrder                    String reorderLevel   products get  ReorderLevel                    String discontinued   products get  Discontinued                        perform program logic here                 System out println productID         productName                              products close               catch  FileNotFoundException e                e printStackTrace              catch  IOException e                e printStackTrace                          Write   Append to CSV file  Code                  For Writing                               import java io File  import java io FileWriter  import java io IOException   import com csvreader CsvWriter   public class CsvWriterAppendExample        public static void main String   args             String outputFile    users csv               before we open the file check to see if it already exists         boolean alreadyExists   new File outputFile  exists             try                  use FileWriter constructor that specifies open for appending             CsvWriter csvOutput   new CsvWriter new FileWriter outputFile  true                         if the file didn t already exist then we need to write out the header line             if   alreadyExists                                csvOutput write  id                    csvOutput write  name                    csvOutput endRecord                                 else assume that the file already has the correct header line                 write out a few records             csvOutput write  1                csvOutput write  Bruce                csvOutput endRecord                 csvOutput write  2                csvOutput write  John                csvOutput endRecord                 csvOutput close              catch  IOException e                e printStackTrace

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We use JavaCSV  it works pretty well

User · Answer

Update  The code in this answer is for Super CSV 1 52  Updated code examples for Super CSV 2 4 0 can be found at the project website  http   super-csv github io super-csv index html    The SuperCSV project directly supports the parsing and structured manipulation of CSV cells  From http   super-csv github io super-csv examples reading html you ll find e g    given a class  public class UserBean       String username  password  street  town      int zip       public String getPassword     return password        public String getStreet     return street        public String getTown     return town        public String getUsername     return username        public int getZip     return zip        public void setPassword String password    this password   password        public void setStreet String street    this street   street        public void setTown String town    this town   town        public void setUsername String username    this username   username        public void setZip int zip    this zip   zip        and that you have a CSV file with a header  Let s assume the following content  username  password    date         zip   town Klaus     qwexyKiks   17 1 2007    1111  New York Oufu      bobilop     10 10 2007   4555  New York   You can then create an instance of the UserBean and populate it with values from the second line of the file with the following code  class ReadingObjects     public static void main String   args  throws Exception      ICsvBeanReader inFile   new CsvBeanReader new FileReader  foo csv    CsvPreference EXCEL PREFERENCE       try         final String   header   inFile getCSVHeader true         UserBean user        while   user   inFile read UserBean class  header  processors      null            System out println user getZip                   finally         inFile close                  using the following  manipulation specification    final CellProcessor   processors   new CellProcessor         new Unique new StrMinMax 5  20        new StrMinMax 8  35       new ParseDate  dd MM yyyy        new Optional new ParseInt         null

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For the last enterprise application I worked on that needed to handle a notable amount of CSV -- a couple of months ago -- I used SuperCSV at sourceforge and found it simple  robust and problem-free

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There is also CSV Excel Utility  It assumes all thos data is table-like and delivers data from Iterators

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If you intend to read csv from excel  then there are some interesting corner cases   I can t remember them all  but the apache commons csv was not capable of handling it correctly  with  for example  urls    Be sure to test excel output with quotes and commas and slashes all over the place

[java] CSV API for Java

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