How do I read a CSV File with JAVA

Question

I have a probem, and I didnt find any solution yet. Following Problem: I have to read a CSV File which has to look like this:

First Name,Second Name,Age,

Lucas,Miller,17,

Bob,Jefferson,55,

Andrew,Washington,31,

The assignment is to read this CSV File with JAVA and display it like this:

First Name: Lucas

Second Name: Miller

Age: 17

The Attribut Names are not always the same, so it also could be:

Street,Number,Postal Code,ID,

Schoolstreet,93,20000,364236492,

("," has to be replaced with ";")

Also the file Adress is not always the same. I already have the view etc. I only need the MODEL.

Thanks for your help. :))

I already have a FileChooser class in Controller, which returns an URI.

Answer 1

Here is some code that I recently worked on for an interview that might help: https://github.com/KemarCodes/ms3_csv/blob/master/src/main/java/CSVProcess.java

If you always have 3 attributes, I would read the first line of the csv and set values in an object that has three fields: attribute1, attribute2, and attribute3. I would create another class to hold the three values and read all the lines after, creating a new instance each time and reading them in an array list. To print I would just print the values in the attribute class each time alongside each set of values.

Answer 2

If your CSV file(s) always contains a Header Line which indicates the Table Column Names then it's just a matter of catching this line and splitting it so as to place those column names into a String Array (or collection, or whatever). The length of this array determines the amount of data expected to be available for each record data line. Once you have the Column Names it's gets relatively easy from there.

How you acquire your CSV file path and it's format type is obviously up to you but here is a general concept how to carry out the task at hand:

public static void readCsvToConsole(String csvFilePath, String csvDelimiter) {
    String line;                            // To hold each valid data line.
    String[] columnNames = new String[0];   // To hold Header names.
    int dataLineCount = 0;                  // Count the file lines.
    StringBuilder sb = new StringBuilder(); // Used to build the output String.
    String ls = System.lineSeparator();     // Use System Line Seperator for output.

    // 'Try With Resources' to auto-close the reader
    try (BufferedReader br = new BufferedReader(new FileReader(csvFilePath))) {
        while ((line = br.readLine()) != null) {
            // Skip Blank Lines (if any).
            if (line.trim().equals("")) {
                continue;
            }
            dataLineCount++;
            // Deal with the Header Line. Line 1 in most CSV files is the Header Line.
            if (dataLineCount == 1) {
                /* The Regular Expression used in the String#split()
                   method handles any delimiter/spacing situation.*/
                columnNames = line.split("\\s{0,}" + csvDelimiter + "\\s{0,}");
                continue;   // Don't process this line anymore. Continue loop.
            }
            // Split the file data line into its respective columnar slot.
            String[] lineParts = line.split("\\s{0,}" + csvDelimiter + "\\s{0,}");
            /* Iterate through the Column Names and buld a String
               using the column names and its' respective data along
               with a line break after each Column/Data line.     */
            for (int i = 0; i < columnNames.length; i++) {
                sb.append(columnNames[i]).append(": ").append(lineParts[i]).append(ls);
            }
            // Display the data record in Console.
            System.out.println(sb.toString());  
            /* Clear the StringBuilder object to prepare for 
               a new string creation.     */
            sb.delete(0, sb.capacity());        
        }
    }
    // Trap these Exceptions
    catch (FileNotFoundException ex) {
        System.err.println(ex.getMessage());
    }
    catch (IOException ex) {
        System.err.println(ex.getMessage());
    }
}

With this method you can have 1 to thousands of columns, it doesn't matter (not that you would ever have thousands of data columns in any given record but hey....you never know... lol). And to use this method:

// Read CSV To Console Window.
readCsvToConsole("test.csv", ",");