Checked JComboBox

[Laurent Saudmont]

I would like to create a JComboBox with JCheckBox as item in the combobox.
Is it possible? How can i do that?
Great thanks for your response

[Neil Marsden]

Is using a JCheckBoxMenuItem an option?
A JMenu is, for all intensive purposes, a comboBox
and can be placed in a JPanel nested within a JMenuBar.
I suppose the more difficult approach would be to extend the JComboBox class...?
regards,
Neil

[Laurent Saudmont]

Indeed, i don't see how i can extend this to a combobox...

[Nathan Pruett]

You should be making custom ListCellRenderers and ComboBoxEditors to make a check box appear in a Combo box...

Here is some example code of how to do this...

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.plaf.basic.*;
  
public class TestCheck extends JFrame {
    
    private JComboBox combo;
    private Vector v;
    
    public static void main( String[] arg ) {
        new TestCheck();
    }
    
    public TestCheck() {
        super( "Test Check" );
        JPanel p = new JPanel();
        v = new Vector();
        v.add( new TestData( "one", false ) );
        v.add( new TestData( "two", false ) );
        v.add( new TestData( "three", false ) );
        v.add( new TestData( "four", false ) );
        v.add( new TestData( "five", false ) );
        v.add( new TestData( "six", false ) );
        combo = new JComboBox( v );
        combo.setRenderer( new DataRenderer() );
        DataEditor editor = new DataEditor();
        editor.addActionListener( new DataChangeListener() );
        combo.setEditor( editor );
        combo.setEditable( true );
        p.add( combo );
        getContentPane().add( p );
        setDefaultCloseOperation( EXIT_ON_CLOSE );
        setSize( 300, 300 );
        setVisible( true );
    }
    
    private class TestData {
        private boolean bool;
        private String name;
        
        public TestData( String name, boolean bool ) {
            this.name = name;
            this.bool = bool;
        }
        
        public String toString() {
            return name;
        }
        
        public boolean getBool() {
            return bool;
        }
        
        public void setBool( boolean b ) {
            bool = b;
        }
        
        public boolean equals( Object anObject ) {
            if ( anObject instanceof TestData ) {
                if ( anObject.toString().equals( name ) ) {
                    if ( ((TestData)anObject).getBool() == bool  ) {
                        return true;
                    }
                }
            }
            return false;
        }
    }
    
    private class DataRenderer extends JCheckBox implements ListCellRenderer {
        
        public DataRenderer() {
            setOpaque( true );
        }
        
        public Component getListCellRendererComponent(
                JList list, Object value, int index, boolean isSelected, 
                boolean cellHasFocus ) {
            if ( value instanceof TestData ) {
                TestData data = (TestData)value;
                setEnabled( list.isEnabled() );
                setSelected( data.getBool() );
            }
            else {
                setEnabled( false );
                setSelected( false );
            }
            if ( isSelected ) {
                setForeground( list.getSelectionForeground() );
                setBackground( list.getSelectionBackground() );
            }
            else {
                setForeground( list.getForeground() );
                setBackground( list.getBackground() );
            }
            if ( value != null ) {
                setText( value.toString() );
            }
            else {
                setText( "" );
            }
            return this;
        }
    }
    
    private class DataEditor extends BasicComboBoxEditor {
        private JCheckBox check = new JCheckBox();
        private Object o;
        
        public Component getEditorComponent() {
            return check;
        }
        
        public Object getItem() {
            return o;
        }
        
        public void setItem( Object o ) {
            this.o = o;
            if ( o != null ) {
                check.setText( o.toString() );
            }
            if ( o instanceof TestData ) {
                check.setSelected( ( (TestData)o ).getBool() );
            }
        }
        
        public void addActionListener( ActionListener l ) {
            check.addActionListener( l );
        }
        
        public void removeActionListener( ActionListener l ) {
            check.removeActionListener( l );
        }
    }
    
    private class DataChangeListener implements ActionListener {
        public void actionPerformed( ActionEvent e ) {
           if ( e.getSource() instanceof JCheckBox ) {
               JCheckBox check = (JCheckBox)e.getSource();
               Enumeration enum = v.elements();
               while ( enum.hasMoreElements() ) {
                   Object o = enum.nextElement();
                   if ( o.toString().equals( check.getText() ) ) {
                       if ( o instanceof TestData ) {
                           ( (TestData)o ).setBool( check.isSelected() );
                       }
                   }
               }
           }
        }
    }
}