I'm using JComboBox with JTables, but the dropdown menu is only "visible" when it's clicked. How can I change this default behavior and make it always visible and user-friendly?
public void start(){
TableColumn column = table.getColumnModel().getColumn(0);
JComboBox comboBox = new JComboBox();
DefaultComboBoxModel model = new DefaultComboBoxModel();
model.addElement("a");
model.addElement("b");
comboBox.setModel(model);
}
As I understand it, you would like the cells to always look like JComboBoxes, and not jLabels.
This can easily be accomplished by adding a TableCellRenderer to your TableColumn.
Pasting in the following code should have the desired effect.
column.setCellRenderer(new TableCellRenderer() {
JComboBox box = new JComboBox();
#Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
box.removeAllItems();
box.addItem(value.toString());
return box;
}
});
I'm developing an app which has an JTable that needs to have multiline cells. Therefore I extended JTextArea and everything is shown noce, but when I try to edit a cell. the text is shown in a single line, and becomes multilined after edit. I want the text to stay multilined during editting.
Is there a way to do that?
Create your TableCellEditor using a JTextArea (instead of the default behaviour which uses JTextField) and set it to your JTable.
You can use a JEditorPane as well to support text styling, if you wish.
---- Edit2 ----
New TableCellEditor:
class MyTableCellEditor extends AbstractCellEditor implements TableCellEditor {
JComponent component = new JTextArea();
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected,
int rowIndex, int vColIndex) {
((JTextArea) component).setText((String) value);
return component;
}
public Object getCellEditorValue() {
return ((JTextArea) component).getText();
}
}
The background color of the selected item in an uneditable JComboBox is a sort of blue:
I know that you can change it to a different color, such as white, for example with the following code:
jComboBox1.setRenderer(new DefaultListCellRenderer() {
#Override
public void paint(Graphics g) {
setBackground(Color.WHITE);
setForeground(Color.BLACK);
super.paint(g);
}
});
That gives you something like this:
However, if you double-click on that combo-box, some of it turns gray (the part with the triangle and the border):
Is there a way to stop these parts from turning gray when you double-click on it?
Note that, if you call super.paint() first, the whole thing turns dark (including the part behind "Select..."), so that doesn't help.
Not sure what exactly OP is trying to achieve, but here is my JComboBox coloring recipe:
static public void main(String[] args) {
JFrame window = new JFrame("Coloring ComboBox");
window.setSize(170, 150);
window.setLocationRelativeTo(null);
window.setLayout(null);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//---textArea is just for focus switching
JTextArea textArea = new JTextArea();
textArea.setBounds(5, 5, 140, 25);
window.add(textArea);
UIManager.put("ComboBox.selectionBackground", Color.magenta); //---focused background color
//---see comboBox's UIDefaults for more tweaks
JComboBox<String> coloredCombo = new JComboBox<String>(new String[]{"Dog", "Cat", "Bird"});
coloredCombo.setEditable(false);
coloredCombo.setUI(new BasicComboBoxUI() {
#SuppressWarnings({"serial"})
#Override
protected ComboPopup createPopup() {
return new BasicComboPopup(coloredCombo) {
{
//---style popup anyway you like
this.setBorder(BorderFactory.createLineBorder(Color.green, 2));//---popup's border color
}
};
}
#Override
protected JButton createArrowButton() {
//---style arrow button anyway you like
JButton result = new JButton();
result.setBackground(Color.orange);//---button's color
return result;
}
});
coloredCombo.setBorder(BorderFactory.createLineBorder(Color.red, 2));//---border color
coloredCombo.setBackground(Color.yellow); //---not focused background color
coloredCombo.setRenderer(new ListCellRenderer<String>() {
#Override
public Component getListCellRendererComponent(JList<? extends String> list, String value, int index,
boolean isSelected, boolean cellHasFocus) {
JLabel result = new JLabel(value);
result.setOpaque(true);
result.setBackground(isSelected ? Color.cyan : Color.blue); //---item background color
return result;
}
});
coloredCombo.setBounds(5, 35, 140, 25);
window.add(coloredCombo);
window.setVisible(true);
}
Of course, this is just an axample, I recommend you to create a fancy custom class to reuse.
A couple things:
The appearance of the combobox (the display area, the arrow, the drop down) are LAF dependent. Your screen shots suggest WinXP. If you must support any other LAFs, be sure to test that as well, because what works for one LAF may not work for another. I have found this to be particularly true for JComboBoxes.
Like Twister suggests, changing the color by overriding the paint() method likely isn't the best way to do this. Just set the background/foreground color of the combobox itself. If you want to change the color of the dropdown itself (I'm not clear if you want to do this or not), then add a custom renderer that overrides getListCellRendererComponent to set the background/foreground.
public static class CustomRenderer extends DefaultListCellRenderer {
#Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
super.getListCellRendererComponent(list, value, index, isSelected,
cellHasFocus);
setBackground(Color.WHITE);
setForeground(Color.BLACK);
return this;
}
}
The appearance of the grey triangle and border is because the combo box now has focus. You can just make it not focusable, and the coloring will go away. This may not be the behavior you want, however.
JComboBox combo = new JComboBox(new Object[]{"Dog", "Cat", "Bird"});
combo.setBackground(Color.WHITE);
combo.setForeground(Color.BLACK);
combo.setFocusable(false);
First, you should not set the foreground and background in the paint method. You should override the getListCellRendererComponent of your renderer in order to customize it. The default renderer change its aspect if you it has the focus or if it is selected. If you do not want those features reimplements the method.
Then if you add a line border to your renderer (setBorder(BorderFactory.createLineBorder(Color.black)) you will see that what is drawn is not part of your renderer but the combobox itself. So you might have to customize the UI
The swing code that calls getListCellRendererComponent, then calls setForeground and setBackground on the returned component (depending on the whether the component is selected and/or focused). I assume this is for some legacy behavior. Unfortunately, it defeats the purpose of my setting it in the renderer.
I've had some good results with this approach:
The code below circumvents changing the foreground and background by overriding the fg/bg setters to do nothing, then I just call the super implementations to set the colors I want.
public static class CustomRenderer extends DefaultListCellRenderer {
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
super.getListCellRendererComponent(list, value, index, isSelected,
cellHasFocus);
super.setBackground(Color.WHITE);
super.setForeground(Color.BLACK);
return this;
}
public void setForeground(Color c) {}
public void setBackground(Color c) {}
}
Addendum:
The grey border is probably just that, a border. Try the same approach, but also override setBorder.
The background color of the selected item in an uneditable JComboBox is a sort of blue:
Is there any way to make this a different color, such as white, for example?
This should work
jComboBox1.setRenderer(new DefaultListCellRenderer() {
#Override
public void paint(Graphics g) {
setBackground(Color.WHITE);
setForeground(Color.BLACK);
super.paint(g);
}
});
The background assigned by the renderer is overriden by the selection background color of the JList that is used in the popup for the combo box. Check out the "paintCurrentValue" method of the BasicComboBoxUI class. So the workaround would be:
JComboBox comboBox = new JComboBox(...);
Object child = comboBox.getAccessibleContext().getAccessibleChild(0);
BasicComboPopup popup = (BasicComboPopup)child;
JList list = popup.getList();
list.setSelectionBackground(Color.RED);
This will affect the rendering of the popup as well. If you don't want it to affect the popup then you will need to create a custom renderer to specifically set the background of selected items.
Have you tried writing your own, custom, ListCellRenderer?
When that method is asked to provide a cell-rendering component you get the following arguments:
public Component getListCellRendererComponent(JList list,
Object value,
int index,
boolean isSelected,
boolean cellHasFocus) {
This works for me:
myComboBox.setBackground(Color.RED);
myComboBox.repaint();
I am having a table in which i have to adda JButton.
I am doing
TableColumnModel colModel = table.getColumnModel();
colModel.getColumn(0).setCellEditor(new MYCellEditor(new JCheckbox()));
MyCellEditor extends DefaultCellEditor{
public MyCellEditor(JCheckbox checkbox){
super(checkbox);
Jbutton button = new JButton("Start");
//actionlistener for button.
}
}
MyRenderer extends DefaultTablecellRenderer{
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
//return a button for column ==0
}
My understanding is that the Celleditor has same instance of button for all cells in a column. So if i click on one button the text changes from "Start" to "stop" but if i click on button in other row it doesnt work.. After debugging it shows that the text is alreadt Stop .
How can i have different instance of button in each row ?
The article Table Button Column cited in #camickr's previous answer provides a more flexible solution, but you may find the tutorial How to Use Tables: Using Other Editors helpful, too. The ColorEditor discussed there is part of the TableDialogEditDemo, available via Java Web Start. You'll need to change the corresponding ColorRenderer accordingly.