How to read the file, put data in JTable, then modify cell/delete lines and save data to the file? [closed]

Answer 1

but how to edit

You need to override the isCellEditable(...) method of the DefaultTableModel to return true.

delete some lines in JTable using GUI

You need to know which row(s) is selected and then use the removeRow(...) method of the DefaultTableModel to delete the row.

For example:

import java.awt.*;
import java.awt.event.*;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.swing.*;
import javax.swing.table.*;

public class ItemDeletion extends JPanel
{
    private JList<String> list;
    private JTable table;

    public ItemDeletion()
    {
        setLayout( new BorderLayout(5, 5) );

        String[] items =
        {
            "One",
            "Two",
            "Three",
            "Four",
            "Five",
            "Six",
            "Seven",
            "Eight",
            "Nine",
            "Ten"
        };

        //  Add the list

        DefaultListModel<String> listModel = new DefaultListModel<String>();

        for (String item: items)
            listModel.addElement( item );

        list = new JList<String>( listModel );


        JButton listDelete = new JButton( "Delete From List" );
        listDelete.addActionListener( new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                DefaultListModel model = (DefaultListModel)list.getModel();
                int row = list.getSelectedIndex();

                while (row != -1)
                {
                    model.removeElementAt( row );
                    row = list.getSelectedIndex();
                }
            }
        });

        JPanel listPanel = new JPanel( new BorderLayout(5, 5) );
        listPanel.add(new JScrollPane( list ), BorderLayout.CENTER);
        listPanel.add(listDelete, BorderLayout.PAGE_END);

        //  Add the table

        DefaultTableModel tableModel = new DefaultTableModel(0, 1);
        List<String> tableItems = Arrays.asList( items );
        Collections.shuffle( tableItems );

        for (String item: tableItems)
        {
            System.out.println( item );
            tableModel.addRow( new String[]{item} );
        }

        table = new JTable( tableModel );

        table.setAutoCreateRowSorter(true);
        ((DefaultRowSorter)table.getRowSorter()).toggleSortOrder(0);

        JButton tableDelete = new JButton( "Delete From Table" );
        tableDelete.addActionListener( new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                DefaultTableModel model = (DefaultTableModel)table.getModel();
                int row = table.getSelectedRow();

                while (row != -1)
                {
                    int modelRow = table.convertRowIndexToModel( row );
                    model.removeRow( modelRow );
                    row = table.getSelectedRow();
                }
            }
        });

        JPanel tablePanel = new JPanel( new BorderLayout(5, 5) );
        tablePanel.add(new JScrollPane( table ), BorderLayout.CENTER);
        tablePanel.add(tableDelete, BorderLayout.PAGE_END);

        add(listPanel, BorderLayout.LINE_START);
        add(tablePanel, BorderLayout.LINE_END);
    }

    private static void createAndShowGUI()
    {
        JFrame frame = new JFrame("Multiple Item Deletion");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new ItemDeletion(), BorderLayout.NORTH);
        frame.setLocationByPlatform( true );
        frame.pack();
        frame.setVisible( true );
    }

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

save it to the file?

You need to get the data from the DefaultTableModel. You can use the getValueAt(...) method to retrieve each value.

So you would need to create code something like:

for (each row);
{
    StringBuilder sb = new StringBuilder();

    for ( each column)
    {
        Object data = model.getValueAt(...);
        sb.append( data.toString() );
    }

    write the sb.toString() to the file
}