How to serialize object to CSV file

Question

I want to write a Object into CSV file  For XML we have XStream like this So if i want to convert object to CSV do we have any such library      EDIT  I want to pass my list of Bean to a method which should write all the fields of bean to CSV

User · Answer

Two options I just ran into    http   sojo sourceforge net  http   supercsv sourceforge net

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It would be interesting to have a csv serializer as it would take up the minimal space compared to other serializing method   The closest support for java object to csv is stringutils provided by spring utils project  arrayToCommaDelimitedString Object   arr  but it is far from being a serializer   Here is a simple utility which uses reflection to serialize value objects  public class CSVWriter   private static String produceCsvData Object   data  throws IllegalArgumentException  IllegalAccessException  InvocationTargetException       if data length  0                return                Class classType   data 0  getClass        StringBuilder builder   new StringBuilder         Method   methods   classType getDeclaredMethods         for Method m   methods                if m getParameterTypes   length  0                        if m getName   startsWith  get                                  builder append m getName   substring 3   append                                 else if m getName   startsWith  is                                  builder append m getName   substring 2   append                                           builder deleteCharAt builder length  -1       builder append   n        for Object d   data                for Method m   methods                        if m getParameterTypes   length  0                                if m getName   startsWith  get      m getName   startsWith  is                                          System out println m invoke d  toString                         builder append m invoke d  toString    append                                                         builder append   n              builder deleteCharAt builder length  -1       return builder toString       public static boolean generateCSV File csvFileName Object   data        FileWriter fw   null      try               fw   new FileWriter csvFileName           if  csvFileName exists                csvFileName createNewFile            fw write produceCsvData data            fw flush              catch Exception e                System out println  Error while generating csv from data  Error message       e getMessage             e printStackTrace            return false            finally               if fw  null                        try                               fw close                              catch Exception e                                          fw null                      return true         Here is an example value object   public class Product   private String name  private double price  private int identifier  private boolean isVatApplicable  public Product String name  double price  int identifier          boolean isVatApplicable        super        this name   name      this price   price      this identifier   identifier      this isVatApplicable   isVatApplicable    public String getName         return name    public void setName String name        this name   name    public double getPrice         return price    public void setPrice long price        this price   price    public int getIdentifier         return identifier    public void setIdentifier int identifier        this identifier   identifier    public boolean isVatApplicable         return isVatApplicable    public void setVatApplicable boolean isVatApplicable        this isVatApplicable   isVatApplicable          and the code to run the util  public class TestCSV    public static void main String    a        Product   list   new Product 5       list 0    new Product  dvd   24 99  967  true       list 1    new Product  pen   4 99  162  false       list 2    new Product  ipad   624 99  234  true       list 3    new Product  crayons   4 99 127  false       list 4    new Product  laptop   1444 99  997  true       CSVWriter generateCSV new File  C   products csv   list          Output   Name    VatApplicable   Price   Identifier dvd     true            24 99   967 pen     false           4 99    162 ipad    true            624 99  234 crayons false           4 99    127 laptop  true            1444 99 997

User · Answer

You can use gererics to work for any class public class FileUtils lt T gt    public String createReport String filePath  List lt T gt  t        if  t isEmpty              return null             List lt String gt  reportData   new ArrayList lt String gt          addDataToReport t get 0   reportData  0        for  T k   t            addDataToReport k  reportData  1             return  dumpReport filePath  reportData    null   filePath     public static Boolean dumpReport String filePath  List lt String gt  lines        Boolean isFileCreated   false            String   dirs   filePath split File separator       String baseDir    quot  quot       for  int i   0  i  lt  dirs length - 1  i              baseDir     quot   quot    dirs i             baseDir   baseDir replace  quot   quot    quot   quot             File base   new File baseDir       base mkdirs         File file   new File filePath       try           if   file exists                file createNewFile          catch  Exception e            e printStackTrace            return isFileCreated             try  BufferedWriter writer   new BufferedWriter              new OutputStreamWriter new FileOutputStream file   System getProperty  quot file encoding quot                for  String line   lines                writer write line   System lineSeparator                     catch  IOException e            e printStackTrace            return false            return true     void addDataToReport T t  List lt String gt  reportData  int index        String   jsonObjectAsArray   new Gson   toJson t  replace  quot   quot    quot  quot   replace  quot   quot    quot  quot   split  quot    quot  quot        StringBuilder row   new StringBuilder         for  int i   0  i  lt  jsonObjectAsArray length  i              String str   jsonObjectAsArray i           str   str replaceFirst  quot   quot    quot   quot   split  quot   quot   index            if  i    0                if  str    null                    row append str replace  quot   quot  quot    quot  quot                   else                   row append  quot N A quot                            else               if  str    null                    row append  quot    quot    str replace  quot   quot  quot    quot  quot                   else                   row append  quot   N A quot                                      reportData add row toString

User · Answer

For easy CSV access  there is a library called OpenCSV  It really ease access to CSV file content   EDIT  According to your update  I consider all previous replies as incorrect  due to their low-levelness   You can then go a completely diffferent way  the hibernate way  in fact    By using the CsvJdbc driver  you can load your CSV files as JDBC data source  and then directly map your beans to this datasource   I would have talked to you about CSVObjects  but as the site seems broken  I fear the lib is unavailable nowadays

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I wrote a simple class that uses OpenCSV and has two static public methods       static public File toCSVFile Object object  String path  String name        File pathFile   new File path       pathFile mkdirs        File returnFile   new File path   name       try            CSVWriter writer   new CSVWriter new FileWriter returnFile            writer writeNext new String    Member Name in Code    Stored Value    Type of Value             for  Field field   object getClass   getDeclaredFields                  writer writeNext new String   field getName    field get object  toString    field getType   getName                        writer flush            writer close            return returnFile        catch  IOException e            Log e  EasyStorage    Easy Storage toCSVFile failed    e           return null        catch  IllegalAccessException e            Log e  EasyStorage    Easy Storage toCSVFile failed    e           return null           static public void fromCSVFile Object object  File file        try           CSVReader reader   new CSVReader new FileReader file            String   nextLine   reader readNext       Ignore the first line          while   nextLine   reader readNext       null                if  nextLine length  gt   2                    try                       Field field   object getClass   getDeclaredField nextLine 0                        Class lt   gt  rClass   field getType                        if  rClass    String class                            field set object  nextLine 1                          else if  rClass    int class                            field set object  Integer parseInt nextLine 1                           else if  rClass    boolean class                            field set object  Boolean parseBoolean nextLine 1                           else if  rClass    float class                            field set object  Float parseFloat nextLine 1                           else if  rClass    long class                            field set object  Long parseLong nextLine 1                           else if  rClass    short class                            field set object  Short parseShort nextLine 1                           else if  rClass    double class                            field set object  Double parseDouble nextLine 1                           else if  rClass    byte class                            field set object  Byte parseByte nextLine 1                           else if  rClass    char class                            field set object  nextLine 1  charAt 0                          else                           Log e  EasyStorage    Easy Storage doesn t yet support extracting     rClass getSimpleName       from CSV files                                             catch  NoSuchFieldException e                        Log e  EasyStorage    Easy Storage fromCSVFile failed    e                     catch  IllegalAccessException e                        Log e  EasyStorage    Easy Storage fromCSVFile failed    e                                       Close if  nextLine length  gt   2               Close while   nextLine   reader readNext       null        catch  FileNotFoundException e            Log e  EasyStorage    Easy Storage fromCSVFile failed    e         catch  IOException e            Log e  EasyStorage    Easy Storage fromCSVFile failed    e         catch  IllegalArgumentException e            Log e  EasyStorage    Easy Storage fromCSVFile failed    e             I think with some simple recursion these methods could be modified to handle any Java object  but for me this was adequate

User · Answer

Though its very late reply  I have faced this problem of exporting java entites to CSV  EXCEL etc in various projects  Where we need to provide export feature on UI   I have created my own light weight framework  It works with any Java Beans  You just need to add annotations on fields you want to export to CSV  Excel etc   Link  https   github com abhisoni96 dev-tools

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Worth mentioning that the handlebar library https   github com jknack handlebars java can trivialize many transformation tasks include toCSV

User · Answer

First  serialization is writing the object to a file  as it is   AFAIK  you cannot choose file formats and all  The serialized object  in a file  has its own  file format  If you want to write the contents of an object  or a list of objects  to a CSV file  you can do it yourself  it should not be complex  Looks like Java CSV Library can do this  but I have not tried this myself  EDIT  See following sample  This is by no way foolproof  but you can build on this        European countries use  quot   quot  as        CSV separator because  quot   quot  is their digit separator     private static final String CSV SEPARATOR    quot   quot       private static void writeToCSV ArrayList lt Product gt  productList                try                       BufferedWriter bw   new BufferedWriter new OutputStreamWriter new FileOutputStream  quot products csv quot     quot UTF-8 quot                 for  Product product   productList                                StringBuffer oneLine   new StringBuffer                    oneLine append product getId    lt  0    quot  quot    product getId                     oneLine append CSV SEPARATOR                   oneLine append product getName   trim   length      0   quot  quot    product getName                     oneLine append CSV SEPARATOR                   oneLine append product getCostPrice    lt  0    quot  quot    product getCostPrice                     oneLine append CSV SEPARATOR                   oneLine append product isVatApplicable      quot Yes quot     quot No quot                    bw write oneLine toString                     bw newLine                              bw flush                bw close                      catch  UnsupportedEncodingException e             catch  FileNotFoundException e            catch  IOException e           This is product  getters and setters hidden for readability   class Product       private long id      private String name      private double costPrice      private boolean vatApplicable     And this is how I tested  public static void main String   args        ArrayList lt Product gt  productList   new ArrayList lt Product gt         productList add new Product 1   quot Pen quot   2 00  false        productList add new Product 2   quot TV quot   300  true        productList add new Product 3   quot iPhone quot   500  true        writeToCSV productList      Hope this helps  Cheers

[java] How to serialize object to CSV file?

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