JTable从txt文件刷新数据

Question

I want to create a file reader that shows data in a JTable. The data in the file are separated by ',' , ';' , or '.' characters. Here's a small part of it

txt File

12345;Βασ.ίλειος;Τζης;Περικλής;Μαρία;28/06/1984;α1
12346;Βασίλ.ειος;Τζόγλου;Πέτρος;Μαρία;29/06/1984;α1
12347;Βα.σίλειος;Τζόπουλος;Παύ.λος;Μαρία;30/06/1984;α1
12348;Βασίλ.ειος;Τζάκης;Πανα.γιώτης;Μαρία;27/06/1984;α1

I open those records with a default separator (';') as shown in the picture below

When I try to select another separator, the program have to read the file again and then separate data with the new separator. I can see that data cannot be refreshed after all. After urging, I put all essential code into one class in order to be runnable. Plus, I use openCSV.

public class NewClass extends JFrame{
private CSVReader reader;
private DefaultTableModel defaultTableModel;
private final Handle handle;
private final List<String> studentColumnNames;
private FileInputStream fileInputStream;
private InputStreamReader fileReader;
private int numberOfColumns, numberOfRows;
private final JComboBox split;
private final JTable dataDemoTable;
private String[] nextLine;
private String[][] rowData;
CharsetDecoder UTF8_CHARSET;
Container container;
FlowLayout flowLayout;
List<String[]> myEntries;

public NewClass(){
    this.studentColumnNames = new ArrayList<>();
    this.studentColumnNames.add("A");
    this.studentColumnNames.add("B");
    this.studentColumnNames.add("C");
    this.studentColumnNames.add("D");
    this.studentColumnNames.add("E");
    this.studentColumnNames.add("F");
    this.studentColumnNames.add("G");

    this.split = new JComboBox();
    this.split.addItem(";");
    this.split.addItem(".");
    this.split.addItem("tab");

    read();
    populateData();
    this.dataDemoTable = new JTable(new DefaultTableModel(this.rowData, studentColumnNames.toArray())); 
    this.dataDemoTable.setFont(new Font("Calibri", Font.PLAIN,18));
    this.dataDemoTable.setPreferredScrollableViewportSize(new Dimension(490,290));
    this.dataDemoTable.setFillsViewportHeight(true);
    JScrollPane scrollPane = new JScrollPane(this.dataDemoTable);
    container = getContentPane();
    flowLayout = new FlowLayout();
    container.setLayout(flowLayout);
    container.add(scrollPane);
    container.add(this.split);
    close();

    this.handle = new Handle();
    this.split.addItemListener(handle);
}

private int getNumberOfColumnsFromFile(){
    //Estimating number of columns from file
    this.numberOfColumns = 0;
    try {
        this.nextLine = this.reader.readNext();
    } catch (IOException ex) {
        Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
    }
    if(this.nextLine != null){
        this.numberOfColumns = this.nextLine.length;
    }
    return this.numberOfColumns;
}

private void close(){
    try {
        this.fileInputStream.close();
        this.fileReader.close();
        this.reader.close();
    }
    catch (IOException ex) {
        Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private void populateData(){
    try {
        myEntries = this.reader.readAll();
    } catch (IOException ex) {
        Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
    }
    this.rowData = myEntries.toArray(new String[0][]);
}

private void read(){
    try {
        this.fileInputStream = new FileInputStream("D:\\Book2.txt"); //the txt file above
        UTF8_CHARSET = StandardCharsets.UTF_8.newDecoder();
        UTF8_CHARSET.onMalformedInput(CodingErrorAction.REPLACE);
        this.fileReader = new InputStreamReader(this.fileInputStream, UTF8_CHARSET);
        this.reader = new CSVReader(this.fileReader, this.split.getSelectedItem().toString().charAt(0));

        if(getNumberOfColumnsFromFile() > studentColumnNames.size()){
            int remainder = getNumberOfColumnsFromFile()-studentColumnNames.size();
            for(int i = 1; i <= remainder; i++){
                //add one more name to studentColumnNames
                studentColumnNames.add("" + (i) + "");
            }
        }
    } 
    catch (FileNotFoundException ex) {
        Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null, ex);
    }
}

public void setVisibilityToView(){setVisible(true);}
public void setNumberOfColumns(int numberOfColumns){this.numberOfColumns = numberOfColumns;}
public void setSizeToView(int width,int height){setSize(width, height);}
public void setDefaultCloseOperationToView(){setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}

public class Handle implements ItemListener{

    @Override
    public void itemStateChanged(ItemEvent e) {
        read();
        populateData();
        close();
    }

}
}

Could someone please suggest a solution to that problem? Thank you.

Answer 1

Have a look at the following example. Yours what a little hard to follow, especially because I am not familiar with OpenCSV.

If you look at the getModelFromCsvFile it prettey much serves the same function as your read() method, except I return a DefaultTableModel and use a split instead. You can use your own implementation for the method. You just need to use the delimiter to set it in open csv. I am not sure how to set the delimiter with open csv, but I'm sure if you know the api, it's something trivial

If you look at the getDelimiterComboBox , I create the combo box with an ActionListener. When the value in the combo box changes, I call the getModelFromCsvFile and then set a new model for the table.

It should be pretty easy to follow, but this is the basic idea you want to go after.

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

public class ReadFileDemo {

    private String defaultFile = "D:\\Book.txt";
    private File currentFile = new File(defaultFile);
    private JTable table;

    public ReadFileDemo() {
        DefaultTableModel model = getModelFromCsvFile(currentFile, ";");
        table = new JTable(model);
        JFrame frame = new JFrame();
        frame.add(new JScrollPane(table));
        frame.add(getDelimiterComboBox(new String[] {";", ".", "\t"}), BorderLayout.NORTH);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    /**
     * Similar to your read() method
     */
    public DefaultTableModel getModelFromCsvFile(File file, String delimiter) {
        DefaultTableModel model = null;
        String line;
        boolean isFirstLine = true;
        try(BufferedReader reader = new BufferedReader(new FileReader(file))) {
            while ((line = reader.readLine()) != null) {
                String[] row = line.split(delimiter);
                if (isFirstLine) {
                    Object[] header = getTableColumnHeaders(row.length);
                    model = new DefaultTableModel(header, 0);
                    model.addRow(row);
                    isFirstLine = false;
                } else {
                    if (model != null) {
                        model.addRow(row);
                    }
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return model;
    }

    public JComboBox getDelimiterComboBox(String[] delimiters) {
        final JComboBox cbox = new JComboBox(delimiters);
        cbox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String delimiter = cbox.getSelectedItem().toString();
                DefaultTableModel model = getModelFromCsvFile(currentFile,
                        delimiter);
                table.setModel(model);
            }
        });
        return cbox;
    }

    public Object[] getTableColumnHeaders(int size) {
        Object[] header = new Object[size];
        for (int i = 0; i < header.length; i++) {
            header[i] = i + 1;
        }
        return header; 
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){
            public void run() {
                new ReadFileDemo();
            }
        });
    }
}

---

UPDATE

Using CSVReader in the read() method.

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.StandardCharsets;
import java.util.List;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

import au.com.bytecode.opencsv.CSVReader;

public class ReadFileDemo {

    private String defaultFile = "D:\\Book.txt";
    private File currentFile = new File(defaultFile);
    private JTable table;
    private CSVReader reader;
    private CharsetDecoder UTF8_CHARSET;

    public ReadFileDemo() {
        DefaultTableModel model = getModelFromCsvFile(currentFile, ";");
        table = new JTable(model);
        JFrame frame = new JFrame();
        frame.add(new JScrollPane(table));
        frame.add(getDelimiterComboBox(new String[] { ";", ".", "\t" }),
                BorderLayout.NORTH);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    /**
     * Similar to your read() method
     */
    public DefaultTableModel getModelFromCsvFile(File file, String delimiter) {
        DefaultTableModel model = null;
        boolean isFirstRow = true;
        try {
            UTF8_CHARSET = StandardCharsets.UTF_8.newDecoder();
            UTF8_CHARSET.onMalformedInput(CodingErrorAction.REPLACE);
            reader = new CSVReader(new InputStreamReader(new FileInputStream(file),
                    UTF8_CHARSET), delimiter.charAt(0));
            List<String[]> dataList = reader.readAll();
            for (String[] row: dataList) {
                if (isFirstRow) {
                    model = new DefaultTableModel(getTableColumnHeaders(row.length), 0);
                    model.addRow(row);
                    isFirstRow = false;
                }
                else {
                    if (model != null) {
                        model.addRow(row);
                    }
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return model;
    }

    public JComboBox getDelimiterComboBox(String[] delimiters) {
        final JComboBox cbox = new JComboBox(delimiters);
        cbox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String delimiter = cbox.getSelectedItem().toString();
                DefaultTableModel model = getModelFromCsvFile(currentFile,
                        delimiter);
                if (model != null) {
                    table.setModel(model);
                }
            }
        });
        return cbox;
    }

    public Object[] getTableColumnHeaders(int size) {
        Object[] header = new Object[size];
        for (int i = 0; i < header.length; i++) {
            header[i] = i + 1;
        }
        return header;
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new ReadFileDemo();
            }
        });
    }
}