How to process a file returned from JFileChooser in Java

Question

I have an application to create graphic representation of data. I use this method on JFreeCharts methods to create the charts using the lists parameters. I need to process the file returned from JFileChooser. Here is my class:

public class ReadGCFile {
static File theFile;
static JFileChooser fileChooser = new JFileChooser();
static JButton theButton = new JButton("Choose the file to represent");

public static void readGCList(List<String> gcArrayList,
        List<String> gcStringList, List<String> gcDateList)
        throws NumberFormatException, IOException, ParseException {
    String line = "";
    String[] tokens = null;
    FileReader fr = null;
    BufferedReader bufReader = null;

    theButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            int returnValue = fileChooser.showOpenDialog(null);
            if (returnValue == JFileChooser.APPROVE_OPTION) {
                theFile = fileChooser.getSelectedFile();

            }
        }
    });

    try {

        fr = new FileReader(theFile);

        bufReader = new BufferedReader(fr);
        while ((line = bufReader.readLine()) != null) {
            line = line.replace(",", ".");
            tokens = line.split(";");

            gcDateList.add(tokens[0]);
            gcStringList.add(tokens[1]);
            gcArrayList.add(tokens[2]);
            gcArrayList.add(tokens[3]);
            gcArrayList.add(tokens[4]);

        }

    } catch (FileNotFoundException es) {
        System.out.println("The file was not found.");

    } catch (NullPointerException e) {
        System.out.println("No files were chosen !");
    }

    catch (IOException e) {

        bufReader.close();

    }

    for (int i = 0; i < gcDateList.size(); i++) {
        SimpleDateFormat currentFormat = new SimpleDateFormat(
                "yyyy-MM-dd hh:mm:ss");
        SimpleDateFormat convertedFormat = new SimpleDateFormat(
                "dd MMM hh:mm:ss");

        gcDateList.set(i, convertedFormat.format(currentFormat
                .parse(gcDateList.get(i))));

    }

}

}

How can I keep the value of "theFile" from the button's actionlistener. In the "try" block, "theFile" is null.

Answer 1

Process the file only when you have one, that is, in the actionPerformed method.

Example :

Put all your processing logic inside one method :

private static void processFile(File theFile, List<String> gcArrayList,
        List<String> gcStringList, List<String> gcDateList){

    String line = "";
    String[] tokens = null;
    FileReader fr = null;
    BufferedReader bufReader = null;

   try {

        fr = new FileReader(theFile);

        bufReader = new BufferedReader(fr);
        while ((line = bufReader.readLine()) != null) {
            line = line.replace(",", ".");
            tokens = line.split(";");

            gcDateList.add(tokens[0]);
            gcStringList.add(tokens[1]);
            gcArrayList.add(tokens[2]);
            gcArrayList.add(tokens[3]);
            gcArrayList.add(tokens[4]);

        }

    } catch (FileNotFoundException es) {
        System.out.println("The file was not found.");

    } catch (NullPointerException e) {
        System.out.println("No files were chosen !");
    }

    catch (IOException e) {

        bufReader.close();

    }

    for (int i = 0; i < gcDateList.size(); i++) {
        SimpleDateFormat currentFormat = new SimpleDateFormat(
                "yyyy-MM-dd hh:mm:ss");
        SimpleDateFormat convertedFormat = new SimpleDateFormat(
                "dd MMM hh:mm:ss");

        gcDateList.set(i, convertedFormat.format(currentFormat
                .parse(gcDateList.get(i))));

    }

}

Then, call it from the actionPerformed method :

theButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            int returnValue = fileChooser.showOpenDialog(null);
            if (returnValue == JFileChooser.APPROVE_OPTION) {
                theFile = fileChooser.getSelectedFile();
                processFile(theFile,gcArrayList,gcStringList,gcDateList);

            }
        }
    });

Also, depending on your needs, you may consider resetting the lists between two files processing.