CODEWITHSUNDEEP
javaserializationjtable
Cohen
Cohen

Reputation: 79

Serialization Jtable

I have a program which basically creates a JTable and JButton. What I have tried is when I press the button, it saves the data of the JTable into a file. When I press it, it throws me an error:

class Demo extends AbstractTableModel
{

    String[] colum = {"first", "Second", "Third"};
    
    Object[][] rowData = {{"Name", 21, "Garzon"},{"Matew", 31, "Herliya"},{"Paul", 24, "Illonis"}};
    
    @Override
    public int getColumnCount()
    {
        return colum.length;
    }

    @Override
    public int getRowCount()
    {
        return rowData.length;
    }

    @Override
    public Object getValueAt(int row, int col)
    {
        return rowData[row][col];
        
    }
    
    public boolean isCellEditable(int row, int col)
    {
        if(col <3)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    
    public void setValueAt(Object value, int row, int col)
    {
        rowData[row][col] = value;
    }
    

}

public class AbstractTableDemo extends JFrame
{
    public AbstractTableDemo()
    {
        setSize(400, 400);
        setLayout(null);
        
        Demo demo = new Demo();
        JTable t = new JTable(demo);
        t.setModel(demo);
        
        JScrollPane sc = new JScrollPane(t);
        sc.setBounds(0, 0, 220, 150);
        add(sc);
        
        JButton b = new JButton("save");
        b.setBounds(0, 200, 100, 30);
        b.addActionListener(new ActionListener()  //Right here i implemente a button which takes the dta from jtable to sav it into a file

        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                
                try
                {
                    DefaultTableModel model = (DefaultTableModel)t.getModel();
                    ObjectOutputStream fileOut = new ObjectOutputStream(new FileOutputStream("C:/Users/Harry/Desktop/clients.txt"));
                    fileOut.writeObject(model);
                    fileOut.close();
                    System.out.println("Write done");
                
                } catch (IOException e1)
                {
                    e1.printStackTrace();
                }
            }
        });
        add(b);
        
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
    
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            
            @Override
            public void run()
            {
                new AbstractTableDemo();
            }
        });
    }
}

When I run the code throws me a:

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: Demo cannot be cast to javax.swing.table.DefaultTableModel

at AbstractTableDemo$1.actionPerformed(AbstractTableDemo.java:87)

How can I fix this?

Upvotes: 0

Views: 1155

Answers (1)

copeg
copeg

Reputation: 8348

class Demo extends AbstractTableModel

Your class Demo extends AbstractTableModel, not DefaultTableModel, so when you cast...

(DefaultTableModel)t.getModel();

...the exception is thrown (DefaultTableModel is a child class of AbstractTableModel). Make the appropriate cast to AbstractTableModel, or just avoid the cast entirely and use the returned TableModel. 

AbstractTableModel model = (AbstractTableModel)t.getModel();
//or just 
//TableModel model = t.getModel();

This being said, better to save your row/column data without the need for serialization (eg CSV/tab delim file) for better cross-application compatability.

Upvotes: 1

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