Create, CSVPrint, Append CSV files using Apache

Question

I am writing an application where there are multiple panels (organized in a tabbed pane) that contain a bunch of JCheckBoxes and JComboBoxes each. I'd like to save the user input into a csv file when the user presses a button. The way that I organized this is by making a "save" method in the tabbed pane class. This "save" method calls all save methods in panels. (fyi, saveable is just a LinkedList of panels, and TagCategories is an enum, just a list of names for the header)

TABBED PANE CLASS:

public void save() {
        
        String csvFilePath = "./idk.csv";
        
        if (!new File(csvFilePath).exists()) {
            try (BufferedWriter writer = Files.newBufferedWriter(Paths.get(csvFilePath));
                    CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT.withHeader(TagCategories.class));)
                {       
                    for(Saveable saveable:saveablePanes) {
                        saveable.save();
                    }
                
                } catch (IOException ex) {
                    System.out.println(ex.getMessage());
                }
        } else {
            
            for(Saveable saveable:saveablePanes) {
                        saveable.save();
                    }
        }

For each panel, I'll have a save() method that saves the info from the panel

PANEL A CLASS:

@Override
    public void save() {
        
        ArrayList <String> selected = new ArrayList<>();
        selected.addAll(bfCBG.getSelected());
        selected.addAll(igCBG.getSelected());

         Map<TagCategories, List <String>> m = new HashMap<>();
            m.put(TagCategories.ID, selected);
            m.put(TagCategories.NUM, Arrays.asList((String)num.getSelectedItem()));
            m.put(TagCategories.GROUP,Arrays.asList((String)groupSelector.getSelectedItem()));
            
            try (BufferedWriter writer = Files.newBufferedWriter(Paths.get(csvFilePath),StandardOpenOption.APPEND);
                    CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT.withHeader(TagCategories.class));)
            {
            csvPrinter.printRecord(Arrays.asList(TagCategories.values())
                    .stream()
                    .map(header -> m.get(header))
                    .collect(Collectors.toList()));

            } catch (IOException ex) {
               System.out.println(ex.getMessage());
            }
        
        System.out.println("Panel A info saved");
        
    }

Two issues:

1. What I want to do is to create a csv file if the file doesn't exist (this should be done within the tabbed pane class), and save the panel's info without overwriting the previous row. If the file already exists, just append the info to file. Right now, it would write the info after creating a new file (when there's no file) and it would overwrite if I click save button again with different info.

2. Also, I ultimately need to solve the problem of writing the same information multiple times in different rows when the user presses the button multiple times. The idea is to match the very first column of the info in the csv file and try overwriting on that row, instead of creating a new row. Any ideas/suggestions for how to go about this is appreciated!

Answer 1

I would not work with csv but with xml. A timestamp is saved for each entry. So you can find out the last change over time. For example:

<?xml version="1.0" encoding="UTF-8" ?>
<entry>
    <panel>
        <id>1</id>
        <name>Tom</name>
        <time>2022.04.21-19:56:37</time>
    </panel>
    <panel>
        <id>1</id>
        <name>Tom</name>
        <time>2022.04.21-22:56:37</time>
    </panel>
    <panel>
        <id>2</id>
        <name>Tim</name>
        <time>2022.04.21-22:56:37</time>
    </panel>
</entry>