Writing to existing CSV file

[tuxman]

Hello !

I have many CSV files like this:

Dist H G
12.5 6.67 8.76
3.54 8.32 7.43


I want to make a simple application in Java for:
-choose a CSV file(with File Chooser Dialog)
-create a new column("Sum") and put the result of ("H" + "G") there

The result CSV:
Dist H G Sum
12.5 6.67 8.76 15.43
3.54 8.32 7.43 15.75

Please help me to write the code.

Thank you very much in advance

[Norm]

Break the task up into a list of simple steps and do one step at a time
Start with a simple program that reads the file and parses the columns on each line into an array.
Then add the extra column to the array
Then write the contents of the array to a disk file.

[quad64bit]

Yeah, Norm outlined a good process. Are you having trouble with a specific portion of your code?

[tuxman]

Till now, my code is:

public static void main(String[] args) {

try {


Scanner myfile = new Scanner(new FileReader("test1.csv"));

while (myfile.hasNextLine()) {
String[] cols = myfile.nextLine().split(";", 2);
System.out.println("col1: " + cols[0] + ", col2:" + cols[1]);
}

myfile.close();



} catch (Exception e) {
e.printStackTrace();
}

}

Then add the extra column to the array

How ?

Thank very much

[Norm]

See the Arrays class for utility method to copy old array to new array.

[tuxman]

How do I add new column to my array ?

With System.arraycopy ?!

[Norm]

Did you try the Arrays class method? What happened?

[tuxman]

Hello Sir !
I don't know how to add a new column.
So, please help me.

Thank you very much in advance

[Norm]

The Arrays class method will copy data from one array into a new array and add extend the size of the new array.
For example if you have a String[4] it will copy the 4 elements from that array into a String[5] array, adding an extra element to the end of the array.