AbstractTreeModel Cannot insert rows correctly

[victor charles]

Hi, all:
I want to use JTable to show some data in my data file. And I extend AbstractTeeModel to implement my data model. But I cannot get what I expected. I have written a sample code to show my errors. Can you help me?
I have highlighted my questions in the source codes.
Thank you very much.
/* MyTableModel.java */
import java.util.Vector;
import javax.swing.table.AbstractTableModel;
public class MyTableModel extends AbstractTableModel {
private String[] columnNames = {"1", "2", "3"};
private Vector tableRows = new Vector();

public MyTableModel(){
}

/* (non-Javadoc)
* @see javax.swing.table.TableModel#getColumnCount()
*/
public int getColumnCount() {
return columnNames.length;
}

public String getColumnName(int col) {
return columnNames[col];

}
/* (non-Javadoc)
* @see javax.swing.table.TableModel#getRowCount()
*/
public int getRowCount() {
return tableRows.size();
}
/* (non-Javadoc)
* @see javax.swing.table.TableModel#getValueAt(int, int)
*/
public Object getValueAt(int rowIndex, int columnIndex) {
Object[] row = (Object[])tableRows.get(rowIndex);
if (row[columnIndex] == null) {
return new String();
}

return row[columnIndex];
}

public Class getColumnClass(int columnIndex) {
return getValueAt(0, columnIndex).getClass();
}

public void addRow(Object[] rowData) {
int rowNumber = tableRows.size();
tableRows.addElement(rowData);
fireTableRowsInserted(rowNumber, rowNumber);
}

}
/* MyFrame.java */
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JTable;
public class MyFrame {
public static void main(String[] args){
JFrame frame = new JFrame("Test");
Container contentPane = frame.getContentPane();
BorderLayout layout = new BorderLayout();
contentPane.setLayout(layout);
// final JLabel label = new JLabel("Hello World");
// frame.getContentPane().add(label);
MyTableModel model = new MyTableModel();
JTable table = new JTable(model);
table.setPreferredSize(new Dimension(100, 100));
contentPane.add(table, BorderLayout.CENTER);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);

Object data[] = new Object[3];
data[0] = new String("0");
data[1] = new String("1");
data[2] = new String("2");
model.addRow(data);

data[0] = new String("3");
data[1] = new String("4");
data[2] = new String("5");
model.addRow(data);
/* I want to get a table like this
0 | 1 | 2
3 | 4 | 5
but I got the following result
3 | 4 | 5
3 | 4 | 5
Can you tell me why? And how I can get the correct result?
*/
}
}

[Craig Wood]

This

        data[0] = "3";
        data[1] = "4";
        data[2] = "5";

actually changes the values in the data array. You added the same array as two different rows.
Try this and see what you get for output:

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JTable;
import java.util.Vector; 
import javax.swing.table.AbstractTableModel; 
 
public class TableTest {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Test");
        CustomTableModel model = new CustomTableModel();
        JTable table = new JTable(model);
        table.setPreferredSize(new Dimension(100, 100));
        frame.getContentPane().add(table, BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
 
        String[] data = new String[3];
        data[0] = "0";
        data[1] = "1";
        data[2] = "2";
        model.addRow(data);
 
        data[0] = "18";        // redefine two
        data[1] = "27";        // array values
 
        data = new String[3];  // old reference points to new array
        data[0] = "3";
        data[1] = "4";
        data[2] = "5";
        model.addRow(data);
        /* I want to get a table like this 
           0 | 1 | 2 
           3 | 4 | 5 
           but I got the following result 
           3 | 4 | 5 
           3 | 4 | 5 
           Can you tell me why? And how I can get the correct result? 
         */
    }
}
 
class CustomTableModel extends AbstractTableModel {
    private String[] columnNames = {"1", "2", "3"}; 
    private Vector tableRows = new Vector();
 
    public CustomTableModel() {}
 
    /* (non-Javadoc)
     * @see javax.swing.table.TableModel#getColumnCount()
     */
    public int getColumnCount() {
        return columnNames.length;
    }
 
    public String getColumnName(int col) {
        return columnNames[col];
    }
 
    /* (non-Javadoc)
     * @see javax.swing.table.TableModel#getRowCount()
     */
    public int getRowCount() {
        return tableRows.size();
    }
 
    /* (non-Javadoc)
     * @see javax.swing.table.TableModel#getValueAt(int, int)
     */
    public Object getValueAt(int rowIndex, int columnIndex) {
        Object[] row = (Object[])tableRows.get(rowIndex);
        if (row[columnIndex] == null) {
            return new String();
        }
        return row[columnIndex];
    }
 
    public Class getColumnClass(int columnIndex) {
        return getValueAt(0, columnIndex).getClass();
    }
 
    public void addRow(Object[] rowData) {
        int rowNumber = tableRows.size();
        tableRows.addElement(rowData);
        fireTableRowsInserted(rowNumber, rowNumber);
    }
}