jtable | Tech Tips & Tricks

If you use a JComboBox as a cell editor in a JTable and you get this error message “component must be showing on the screen to determine its location”, chances are your cell editor is inherited from DefaultCellEditor. Thomas Bang saved us all the trouble in trying to figure out how to make a workaround for this problem by creating a ComboBoxCellEditor class inheriting from AbstractCellEditor.

Pretty cool. This class actually did the trick.

import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.Serializable;
import javax.swing.AbstractCellEditor;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.table.TableCellEditor;
public class ComboBoxPaneledCellEditor extends AbstractCellEditor implements ActionListener, TableCellEditor, Serializable {
    private JComboBox comboBox;
    public ComboBoxPaneledCellEditor(JComboBox comboBox) {
        this.comboBox = comboBox;
        this.comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
        // hitting enter in the combo box should stop cellediting (see below)
        this.comboBox.addActionListener(this);
    }
    private void setValue(Object value) {
        comboBox.setSelectedItem(value);
    }
    @Override
    public void actionPerformed(java.awt.event.ActionEvent e) {
        // Selecting an item results in an actioncommand "comboBoxChanged".
        // We should ignore these ones.
        // Hitting enter results in an actioncommand "comboBoxEdited"
        if(e.getActionCommand().equals("comboBoxEdited")) {
            stopCellEditing();
        }
    }
    // Implementing CellEditor
    @Override
    public Object getCellEditorValue() {
        return comboBox.getSelectedItem();
    }
    @Override
    public boolean stopCellEditing() {
        if (comboBox.isEditable()) {
            // Notify the combo box that editing has stopped (e.g. User pressed F2)
            comboBox.actionPerformed(new ActionEvent(this, 0, ""));
        }
        fireEditingStopped();
        return true;
    }
    @Override
    public Component getTableCellEditorComponent(javax.swing.JTable table, Object value, boolean isSelected, int row, int column) {
        setValue(value);
        return comboBox;
    }
}

import java.awt.Component;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.io.Serializable;

import javax.swing.AbstractCellEditor;

import javax.swing.JComboBox;

import javax.swing.JComponent;

import javax.swing.table.TableCellEditor;

public class ComboBoxPaneledCellEditor extends AbstractCellEditor implements ActionListener, TableCellEditor, Serializable {

private JComboBox comboBox;

public ComboBoxPaneledCellEditor(JComboBox comboBox) {

this.comboBox = comboBox;

this.comboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);

// hitting enter in the combo box should stop cellediting (see below)

this.comboBox.addActionListener(this);

}

private void setValue(Object value) {

comboBox.setSelectedItem(value);

}

@Override

public void actionPerformed(java.awt.event.ActionEvent e) {

// Selecting an item results in an actioncommand "comboBoxChanged".

// We should ignore these ones.

// Hitting enter results in an actioncommand "comboBoxEdited"

if(e.getActionCommand().equals("comboBoxEdited")) {

stopCellEditing();

}

// Implementing CellEditor

@Override

public Object getCellEditorValue() {

return comboBox.getSelectedItem();

}

@Override

public boolean stopCellEditing() {

if (comboBox.isEditable()) {

// Notify the combo box that editing has stopped (e.g. User pressed F2)

comboBox.actionPerformed(new ActionEvent(this, 0, ""));

}

fireEditingStopped();

return true;

}

@Override

public Component getTableCellEditorComponent(javax.swing.JTable table, Object value, boolean isSelected, int row, int column) {

setValue(value);

return comboBox;

}

Let’s say you have a JTable component and a save JButton in a form. When you make changes to the data in the JTable, the cell editors would have to save the new changes before you will be able to get the new values. One thing you probably did was to click on some other cell so that the previous cell would lose focus and the new changes will take effect.

But what if you want to click on the save JButton in order to save all the data in the JTable? It is ugly to have to click on some other cell so that changes will take effect and then clicking on the save JButton.

There is a way to go around this and it only involves one line of code.

if (jTable1.getCellEditor() != null) jTable1.getCellEditor().stopCellEditing();

1	if (jTable1.getCellEditor() != null) jTable1.getCellEditor().stopCellEditing();

Place that line of code inside your JButton‘s actionPerformed() method before doing any save. That way, you will be able to get the new values in your JTable.

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Tag: jtable

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