Export 2-D object array (Object[][] array) into a .csv file in Java

Question

I'm working on a java project and using Eclipse with JDK 1.7. I have 2-D array of object type as Object[][] array. I wish to store the contents (export) of array to a csv file (each value in a separate column for each row) on the disk. Here is the code I'm trying:

FileOutputStream fos = new FileOutputStream("newFile.csv");
            ObjectOutputStream oos = new ObjectOutputStream(fos);  
            for(int i=0;i<array.length;i++)
            {
                for(int j=0;j<array[0].length;j++)
                {
                   oos.writeObject(array); 
                   oos.writeObject(",");
                   }
            }
            oos.close();

The output stored in file newFile.csv is as follows:

¬íur[[Ljava.lang.Object;¿ûSäkÛÊxpur[Ljava.lang.Object;ÎXŸs)lxpt1t1tClosedt100.00000000t   
0.00000000uq~t2t1tClosedt200.00000000t100.00000000uq~t3t1tClosedt100.00000000t50.00000000t   q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~q~

which is some garbage value. I need help to figure out what is wrong in this program (how to convert object into a string before storing, this is what I'm guessing the error is), and how to resolve the issue.

I found a help on http://www.tutorialspoint.com/java/io/objectinputstream_readobject.htm but it deals with byte[] and String, not with 2-D object array. Similarly, http://www.mkyong.com/java/how-to-write-to-file-in-java-fileoutputstream-example/ deals with byte[] only. I have also found a solution at Java - How to write ArrayList Objects into txt file?, where ArrayList<String> MenuArray = new ArrayList<String>(); is used instead of 2-D object array, and also the solution is not complete. I also find a help at Using FileUtils in eclipse I'm getting the similar error. The solution says use:

FileUtils.writeLines(new File("input.txt"), array);

However, I receive an error that method writeLine(File, Collection<>) is not applicable for WriteLine(File, Object[][]). Further a solution in ADO.NET exists for reading csv file and store data in 2-D array at Reading a csv file and storing the data in a 2-D object array, but I need the other way and also solution in not for Java.

Both the methods I used are not working. Please note my 2-D array is of Object type not String. Any help is appreciated.

silmx · Accepted Answer · 2015-11-30 23:22:23Z

0

        FileOutputStream fos = new FileOutputStream("newFile.csv");
        ObjectOutputStream oos = new ObjectOutputStream(fos);  
        for(int i=0;i<array.length;i++)
        {
            for(int j=0;j<array[i].length;j++)
            {
               oos.writeObject(array[i][j]); 
               if ( j < array[i].length -1 )
               {
                   oos.writeObject(",");
               } 
               else 
               {
                   oos.wrinteObject("\n");
               }
             }
        }
        oos.close();

edited Nov 30, 2015 at 23:22

answered Nov 30, 2015 at 23:13

silmx

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