How can I update an existing entry in the csv file

Question

I need to update an existing entry in a CSV file using java code. The code that I have written is below. I'm able to match the entry given by the user with the entry in the file, but can't figure how to write a new entry at the same location.

while ((row = reader.readNext()) != null)       
{     
    for (int i = 0; i < 1; i++)                
    {    
        System.out.print("row is "+row[i]);

        // display CSV values                                                
        System.out.println("Cell Value: " + row[i]);  
        System.out.println("User Input: " + t1);
        System.out.println("-------------"); 
        if(t1.equals(row[0]))
        {
            data.add(new String[] { t1, t2, t3, t4, t5, t6, t7, t8, t9, t10,
                     t11, t12, t13, t14, t15, t16, t17, t18, t19, t20, t21, t22,
                     t23, t24, t26, t27, t28, t29, t30, t31, t32, t33, t34, t35,
                     t36, t37, t38, t39 
            });   
            flag=1;
            writer.writeAll(data);
            break;
        }               
    }
    rowno++;
}

possible duplicate of [updating specific cell csv file using java](http://stackoverflow.com/questions/4397907/updating-specific-cell-csv-file-using-java) — Alex K, Dec 22 '13 at 12:18

score 0 · Answer 1 · answered Dec 21 '13 at 16:56

0

This is what you need to do to write a new value to the same location

Have two Files, The input one to read from, and new one to write to
In the loop, read a line from file, and if it doesn't match, write to output file
If found from input file, write new entry in output file.
Finish looping through file.
Close the Streams
Change the name of the output file to the name of the input file.

answered Dec 21 '13 at 16:56

Paul Samsotha

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1

it should be 'Have two files' – Keerthivasan Dec 21 '13 at 16:58
1

What if i need to keep doing this for n times? – user2392588 Dec 21 '13 at 17:20
You might want to look into `RandomAccessFile`. It's a bit more complex, but if you learn to use it, it can be helpful for situations like this – Paul Samsotha Dec 21 '13 at 18:01

How can I update an existing entry in the csv file

1 Answers1