CSVWriter don't allow to write to file

Question

I want to save my data into CSV file. I'm using Scanner to read -> CSVWriter to save.

I got error: incompatibile types: List[String] can't be converted to String[].

method:

private static void insertToFile(String source, String target)
{   
    List<String> data = new ArrayList<String>();
    try{
    Scanner sc = new Scanner(new File(source));

    while (sc.hasNextLine()) {
        data.add(sc.nextLine());
    }
    sc.close();
    }
    catch(Exception e){
    e.printStackTrace();
    }

       File resfile = new File(target);      

        try{
            CSVWriter writer = new CSVWriter(new FileWriter(resfile, true));

             //BufferedWriter bufferedWriter = new BufferedWriter(writer);

            for (String j : data) {
              //writer.writeAll(data);//error here
            }

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

Answer 1

The problem is that

writer.writeAll accept a String[] as input, you are passing a List<String>

changing

for (String j : data) {
   //writer.writeAll(data);//error here
}

to

writer.writeAll(data.toArray(new String[data.size()])); will solve the issue.

Answer 2

Try this instead:

private static void insertToFile(String source, String target)
{
    List<String> data = new ArrayList<>();

    // utilize Scanner implementing AutoCloseable and try-with-resource construct 
    // see https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html )
    try (Scanner sc = new Scanner(new File(source))) {
        while (sc.hasNextLine()) {
            data.add(sc.nextLine());
        }
    }
    catch (Exception e){
        e.printStackTrace();
    }

    File resfile = new File(target);

    try {
        // depending on the CSVWriter implementation consider using try-with-resource as above
        CSVWriter writer = new CSVWriter(new FileWriter(resfile, true));

        writer.writeAll(data.toArray(new String[data.size()]));

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

It converts the list into an array initialized to the length of your list. Also you probably don't want to call writeAll on your entire list for each element in your list, which prints your list into your files multiple times.

Answer 3

There is a simple way of doing it,you can use the below mentioned code. Import these dependencies in your code(import java.io.File,import java.io.FileWriter).

FileWriter writer = new FileWriter(new File(File_path));
writer.write(data);
writer.close();