Swing JCombobox and JTable issue

Hi,

I am unable to add a Combo box in JTable 2nd column of each row with different value. Please help me.. I already try lots of time with many example but I man unable to change the ComboBox value in every row. Is it possible to rander a particular column with different component in every row ?

TableCellRenderer.getTableCellEditorComponent takes both the row and column numbers, so you can use that to your advantage. For example:
Of course you can use a Collection or List instead of an Object[], but the principle is the same.

Thanks Rob Prime. It is working fine.
yours solution helps me a lot.

I have one more doubt that , can not we Render the same cell with different component. Like the same column in first row with JCombo Box and the same column in next row with JTextField.

I have a Map, which I have to display in n-rows and 3-column table ... where for rew columns the value need to select from combobox and few need to enter. The number of rows we cant define... because it is dynamic.

Sure, just return a JTextField from that method.

The following class for instance uses a JComboBox, JTextField and a JCheckBox:

class MyCellEditor implements TableCellEditor
{
    private TableCellEditor comboBox = new DefaultCellEditor(new JComboBox());
    private TableCellEditor textField = new DefaultCellEditor(new JTextField());
    private TableCellEditor checkBox = new DefaultCellEditor(new JCheckBox());

private TableCellEditor current;

public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column)
    {
        if (shouldUseComboBox(value, row, column))
        {
            current = comboBox;
            JComboBox combo = (JComboBox)current.getTableCellEditorComponent(...);
            // fill as before
            return combo;
        }
        if (shouldUseCheckBox(value, row, column))
        {
            current = checkBox;
            JCheckBox check = (JCheckBox)current.getTableCellEditorComponent(...);
            // set selected as needed
            return check;
        }
        // default to text field
        current = textField;
        JTextField field = (JTextField)curernt.getTableCellEditorComponent(...);
        // modify as needed
        return field;
    }

public Obect getCellEditorValue()
    {
        return (current == null ? null : current.getCellEditorValue());
    }

public void cancelCellEditing()
    {
        if (current != null) current.cancelCellEditing();
    }

public void addCellEditorListener(CellEditorListener l)
    {
        comboBox.addCellEditorListener(l);
        textField.addCellEditorListener(l);
        checkBox.addCellEditorListener(l);
    }

// implement other methods similarly
}

Thanks, It is working fine.

I face one more problem that, when i click on Cell for edit,then the scope is remains their till i will not give enter , in the case of JTextField.
Similarly in JComboBox the Scope is remain there till if I will not select any value from JComboBox.

Is there any way that it will lose its scope when i will click on any other cell.

Instead of putting all the code in a custom editor, override the getCellEditor(...) method of JTable to return the appropriate editor for the row and column.

Hi Rob,

I can not understand / follow your suggestion can you please define it more clearly.

Rob Camick wrote:Instead of putting all the code in a custom editor, override the getCellEditor(...) method of JTable to return the appropriate editor for the row and column.

Uhm yeah, that would be better

Rob means this (which I used myself for a similar situation as well... why did I forget?):

Hi,

I do have a similar requirement, My JTable's first column comprises of check boxes and third column comprises
of JComboBox (a unique one for each row). How ever even after implementing the "MyTableCellEditor" class as
Rob suggested, I am getting the following exception.

java.lang.NullPointerException
at TestFrame$MyTableModel.getColumnClass(TestFrame.java:297)
at javax.swing.JTable.getColumnClass(JTable.java:1752)
at javax.swing.JTable.getCellRenderer(JTable.java:3700)
at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:1148)
at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:1051)
at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:974)

Can you please suggest whats going wrong. I can post my code if needed.

Thanks
Avirup

Avirup Das wrote:java.lang.NullPointerException
at TestFrame$MyTableModel.getColumnClass(TestFrame.java:297)

So, what's on line 297 of TestFrame.java, inside method getColumnClass of inner class MyTableModel?

Hi Rob,

Let me post my code. It is just a small version of the actual code.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.table.*;

public class TestFrame extends JFrame implements ActionListener
{
public String[] sourceName = {"D0","D1","D2"};
public String[] sourceType = {"SMI","EFI","SMI"};
public String[] targetName = {"None","T0","T1","T2","T3","T4","T5"};
public String[] targetType = {"-","SMI","EFI","SMI","EFI","SMI","EFI"};
public HashMap sourceMap = new HashMap();
public HashMap targetMap = new HashMap();
public HashMap editors = new HashMap();

public TestFrame()
{
sourceMap.put(sourceName[0],sourceType[0]);
sourceMap.put(sourceName[1],sourceType[1]);
sourceMap.put(sourceName[2],sourceType[2]);

targetMap.put("None","-");
targetMap.put(targetName[0],targetType[0]);
targetMap.put(targetName[1],targetType[1]);
targetMap.put(targetName[2],targetType[2]);
targetMap.put(targetName[3],targetType[3]);
targetMap.put(targetName[4],targetType[4]);
targetMap.put(targetName[5],targetType[5]);

initComponents();
populateTable();
}
private void initComponents()
{
scrollPane = new JScrollPane();
table = new JTable(new MyTableModel());
setDefaultCellRendering();
// Rest of the GUI related code
}
private void populateTable()
{
for(int i=0;i<sourceName.length;i++)
{
table.setValueAt("-",i,1);
table.setValueAt("-",i,2);
table.setValueAt("-",i,3);
table.setValueAt("-",i,4);
table.setValueAt(new Boolean(false),i,0);
}
for(int i=0;i<sourceName.length;i++)
{
table.setValueAt(sourceName[i],i,1);
table.setValueAt(sourceType[i],i,2);
for(int j=0;j<targetName.length;j++)
{
if(!isTargetMapped(j)&&isLabel(sourceName[i],targetName[j]))
{
table.setValueAt(new Boolean(true),i,0);
table.setValueAt(targetName[j],i,3);
table.setValueAt(targetType[j],i,4);
break;
}
}
}
}
public boolean isTargetMapped(int count)
{
boolean flag = false;
for(int i=0;i<sourceName.length;i++)
{
String target = (String)this.table.getValueAt(i,3);
if(target.equals(targetName[count]))
flag = true;
}
return flag;
}
public boolean isLabel(String source,String target)
{
String srcType = (String)sourceMap.get(source);
String tgtType = (String)targetMap.get(target);
return srcType.equalsIgnoreCase(tgtType);
}
private void setDefaultCellRendering()
{
DefaultTableCellRenderer cr = new DefaultTableCellRenderer();
cr.setHorizontalAlignment(JLabel.CENTER);

TableColumn column = null;

column = null;
column = table.getColumnModel().getColumn(0);
column.setPreferredWidth(30);

column = null;
column = table.getColumnModel().getColumn(1);
column.setCellRenderer(cr);

column = null;
column = table.getColumnModel().getColumn(2);
column.setCellRenderer(cr);

column = null;
column = table.getColumnModel().getColumn(3);
column.setCellEditor(new MyTableCellEditor());
// column.setCellRenderer(cr);

column = null;
column = table.getColumnModel().getColumn(4);
column.setCellRenderer(cr);
}
public Vector getComboItems(int row,int col)
{
Vector vect = new Vector();
vect.add("None");
for(int j=0;j<targetName.length;j++)
if(isLabel(sourceName[col],targetName[j]))
vect.add(targetName[j]);
return vect;
}
class MyTableModel extends AbstractTableModel
{
String[] columnNames = {"","Source Disk","Label","Target Disk","Label"};
Object[][] data = new Object[sourceName.length][5];
public int getColumnCount()
{
return this.columnNames.length;
}
public int getRowCount()
{
return this.data.length;
}
// Get Table Column Name
public String getColumnName(int col)
{
return columnNames[col];
}
// Get Table row-column(cell) value
public Object getValueAt(int row,int col)
{
return data[row][col];
}
// JTable uses this method to determine the default
// renderer/editor for each cell.If we didn't implement
// this method then the First Column will contain the
// text "true/false" inspite of a CheckBox.
public Class getColumnClass(int c)
{
return getValueAt(0, c).getClass();
}
public boolean isCellEditable(int row,int col)
{
boolean flag = false;
if(col==3)
{
boolean bool = ((Boolean)getValueAt(row,0)).booleanValue();
if(bool)
flag = true;
}
return flag;
}
// Don't implement this method unless the Table Data
// can change.
public void setValueAt(Object value,int row,int col)
{
if(col==0)
repaint();
data[row][col] = value;
fireTableCellUpdated(row,col);
}
}
class MyTableCellRenderer extends JLabel implements TableCellRenderer
{
public Component getTableCellRendererComponent( JTable table,
Object value,
boolean isSelected,
boolean hasFocus,
int rowIndex,
int colIndex
)
{

setText((String)value);
return this;
}
}
class MyTableCellEditor extends DefaultCellEditor
{
public MyTableCellEditor()
{
super(new JComboBox());
}
public Component getTableCellEditorComponent(JTable table,Object value,boolean isSelected,int row,int col)
{
JComboBox combo = (JComboBox)super.getTableCellEditorComponent(table,value,isSelected,row,col);
combo.removeAllItems();
Vector vect = getComboItems(row,col);
for(int i=0;i<vect.size();i++)
combo.addItem((String)vect.get(i));

return combo;
}
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource() instanceof JComboBox)
comboClicked(table.getSelectedRow());
}
public void comboClicked(int row)
{
try
{
if(row!=-1)
{
String target= (String)table.getValueAt(row,2);
String type = (String)this.targetMap.get(target);
table.setValueAt(type,row,3);
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
}
public static void main(String args[])
{
new TestFrame();
}
private JScrollPane scrollPane;
private JTable table;
private JComboBox comboBox;
}

Thanks
Avirup

Rob Prime wrote:So, what's on line 297 of TestFrame.java, inside method getColumnClass of inner class MyTableModel?

Avirup Das wrote:Let me post my code. It is just a small version of the actual code.

getValueAt(0, c) returns null for some column.

Also, don't post such large pieces of code when only a small piece is needed. And if you post code, UseCodeTags.

Hi Rob,

I do agree with you that the method getValueAt(0, c) is giving NullPointerException for some column.
Actually the problem was with the String array declaration and the respective values being assigned.

public String[] targetName = {"None","T0","T1","T2","T3","T4","T5"};

.

I have fixed that problem and eventually integrated with my main project and the good news is its working
fine now.

However extending DefaultCellEditor didn't solved my purpose.I don't know why but it didn't. I think I had
missed out something. So I have created a subclass of JTable and override the getCellEditor() method
and it seems that the problem is resolved.

Thanks for your response
Avirup