How to make a combobox, inside a jtree, show its menu?

Question

I basically have a JTree where I show certain information. In one of the "sub-trees" I got a panel which consists of a panel with GridLayout(0,2) and a JPanel as well as a combobox.

I've noticed that no components in my tree react on input. This of course means that my combobox won't react when I try to click on it. I tried to implement a default cell editor, which worked but not like I wanted to. It basically opened the menu but when I selected one of the items it replaced the JLabel so only the combobox was visible.

Pictures

Before clicking on the box

After clicking on the box

Code that I tried with

 TreeCellEditor editor = new DefaultCellEditor(blockedAlternatives);
                infoTree.setEditable(true);
                infoTree.setCellEditor(editor);

I obviously don't want to be able to edit the whole tree, I just want to be able to show the combobox's menu. I just took this code from the web for testing. Any ideas?

Answer 1

It basically opened the menu but when I selected one of the items it replaced the JLabel so only the combobox was visible.

Well that is what you'd excpect as thats how the DefaultCellEditor(JComboBox jcb) is meant to be:

    import java.awt.BorderLayout;
    import java.util.Properties;
    import javax.swing.*;
    import javax.swing.tree.TreeCellEditor;

    public class TreeEditJComboBox {

        public static void main(String args[]) {
            JFrame frame = new JFrame();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            Properties props = System.getProperties();
            JTree tree = new JTree(props);


            JComboBox comboBox = new JComboBox(new String[]{"A", "B", "C"});
            TreeCellEditor editor = new DefaultCellEditor(comboBox);

            tree.setEditable(true);
            tree.setCellEditor(editor);

            JScrollPane scrollPane = new JScrollPane(tree);
            frame.add(scrollPane, BorderLayout.CENTER);
            frame.setSize(300, 150);
            frame.setVisible(true);
        }

    }
}

You could try making your own DefaultCellEditor and override getTableCellEditorComponent() and then return a JPanel which holds the JLabel and JComboBox , something like:

class MyDefaultCellEditor extends DefaultCellEditor {

public MyDefaultCellEditor(JComboBox comboBox) {
    super(comboBox);
}

@Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
   //return custom coponent
    return super.getTableCellEditorComponent(table, value, isSelected, row, column);
}
}

then:

 TreeCellEditor editor = new MyDefaultCellEditor(blockedAlternatives);

you may have to override a few other methods too. I was just showing the logic

References:

• Creating a DefaultCellEditor: JComboBox

• extends DefaultCellEditor