Importing CSV into JTable on Jpanel (no CSVReader)

Question

A quick Question:

I'm trying to import some information from a CSV into a jtable that is located on a swing panel in my program.

I've imported the information into the actionListener using inputstream and parsed through it with bufferedreader. I just used a simple while loop afterwards to add to the Jtable. however, when I run the app, no information shows up in my jtable.

When I try to debug the program, I have no issues toggling between the two jpanels (and the other information that is on them) its just my jtable that shows up empty.

Here's my code:

public class wert extends JFrame {

    private JPanel contentPane;
    private JPanel panel;
    private JTable table;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    wert frame = new wert();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public wert() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 925, 486);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(new BorderLayout(0, 0));

        JButton btnNewButton = new JButton("New button");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                try {
                    Path filePath = Paths.get("\\test folder\\newNeetest.csv\\");
                    InputStream input = null;

                    input = Files.newInputStream(filePath);
                     BufferedReader reader = new BufferedReader (new InputStreamReader(input));

                     DefaultTableModel model = (DefaultTableModel)table.getModel();

                    Object [] lines = reader.lines().toArray();

                    for (int q =0; q > lines.length; q++) {
                        String dsa = lines[q].toString();
                        String [] dataRow = dsa.split(",");
                        model.addRow(dataRow);
                    }
                    } 


                catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }


            }



            }
        );
        contentPane.add(btnNewButton, BorderLayout.NORTH);

        panel = new JPanel();
        contentPane.add(panel, BorderLayout.CENTER);

        table = new JTable();
        GroupLayout gl_panel = new GroupLayout(panel);
        gl_panel.setHorizontalGroup(
            gl_panel.createParallelGroup(Alignment.LEADING)
                .addGroup(gl_panel.createSequentialGroup()
                    .addGap(475)
                    .addComponent(table, GroupLayout.PREFERRED_SIZE, 230, GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(188, Short.MAX_VALUE))
        );
        gl_panel.setVerticalGroup(
            gl_panel.createParallelGroup(Alignment.LEADING)
                .addGroup(Alignment.TRAILING, gl_panel.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(table, GroupLayout.DEFAULT_SIZE, 0, Short.MAX_VALUE)
                    .addGap(375))
        );
        panel.setLayout(gl_panel);
    }

}

Answer 1

A few problems with your posted code:

1. First of all, it requires an outside file, one that we are not privy to. Fortunately this can be overcome
2. You don't put your JTable into a JScrollPane. Scroll panes are perfect for displaying the full JTable including its column headers.
3. You use GroupLayout, not necessary, and more importantly perhaps messing things up for you, since it limits the visualization of your table
4. You don't give your JTable a decent table model, one with column headers, so when you add new data to it, the model is confused and may not know how many columns to display

Suggestions:

• Put the table into a JScrollPane
• Place that JScrollPane BorderLayout.CENTER -- your contentPane JPanel would work well for this.
• Give the JTable a decent model. Even a most simple DefaultTableModel, one with a column header String array and an int, 0, for the number of initial rows.
• Be sure that the column header String array's length is the actual number of columns needed

For example, your code changed to an MCVE that works:

import java.awt.*;
import java.awt.event.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.DefaultTableModel;

@SuppressWarnings("serial")
public class Wert2 extends JFrame {

    private JPanel contentPane;
    private JTable table;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Wert2 frame = new Wert2();
                    frame.pack();
                    frame.setLocationRelativeTo(null);
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public Wert2() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(new BorderLayout(0, 0));

        JButton btnNewButton = new JButton("New button");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // file I/O code removed for sake of MCVE
                DefaultTableModel model = (DefaultTableModel) table.getModel();
                for (int i = 0; i < 10; i++) {
                    Vector<String> rowData = new Vector<>();
                    for (int j = 0; j < 3; j++) {
                        rowData.add(String.format("[%d, %d]", i, j));
                    }
                    model.addRow(rowData);
                }
            }

        });
        contentPane.add(btnNewButton, BorderLayout.NORTH);

        // contentPane.add(panel, BorderLayout.CENTER);
        String[] colNames = {"A", "B", "C"};
        table = new JTable(new DefaultTableModel(colNames, 0));
        JScrollPane scrollPane = new JScrollPane(table);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        contentPane.add(scrollPane);
    }
}