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Override method that toggles 'isSelected' in getListCellRendererComponent

I would like to make my own method that controles when a component is 'isSelected'.
I have a JList containing multiple JPanel. The constructing class of the JPanel extends ListCellRenderer<>.
To show that one of the JList-component (the JPanels) is selected i use;
#Override
public Component getListCellRendererComponent(..., boolean isSelected, ...) {
if(isSelected){
setBackground(list.getSelectionBackground());
setForeground(list.getSelectionForeground());
} else {
setBackground(list.getBackground());
setForeground(list.getForeground());
}
return this;
}
I would like a method that keeps a selected item 'selected' eventhough I choose to select another. I understand this can be done by holding down CTRL, but .setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION); does not quite do the trick. I would rather like to select multiple by clicking on them, and deselect by clicking on them.
For this i have worked with the ListSelectionMode, but i cant find a way.
When done the above I would like to implement a method that only selects a component in the list when clicked in a certain area (instead of the whole component which is preset). I have made this method, which returns true if the correct area is clicked, else false. But since I cant figure out how to override the mouseevent that makes the components 'isSelected' this has been tricky.
Here is the code for the method I would like to override the 'isSelected' method;
this.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent evt) {
if(ActionHandler.mouseClickedPrebuild(evt.getPoint())){
//This code runs if that special place is clicked!
//So now the component should be 'isSelected' or
//deselected if it already was 'isSelected'.
}
}
});
This code is in the constructor of my JList
And the mouseClickedPrebuild method;
public static boolean mouseClickedPrebuild(Point point) {
int index = theJList.locationToIndex(point);
Rectangle bounds = theJList.getCellBounds(index,index);
Point p = bounds.getLocation();
return ( ... long list of greater than & less than ...);
//This gives the certain area which is accepted to return true

I solved the issue!
So I get my view showing by running this line;
// UI Class JScrollPane Custom JList
UIConstructor.listview.setViewportView(new ListView( -insert ArrayList here- ));
Here is my ListView. The custom DefaultListSelectionModel I used to solve my problem was posted by #FuryComptuers right here;
JList - deselect when clicking an already selected item
I had to make a few changes to the code, since the two methods in the selectionModel will run before my mouseevent. I saved the variabels staticly, so instead of running the code in setSelectionInterval I did it inside my mousePressed.
I then could add the boolean isSelected which returns true, if a curtain area within a specific list element is clicked.
public class ListViewd extends JList {
static boolean isSelected;
static Point point;
static boolean gS = false;
static int in0;
static int in1;
#Override
public Dimension getPreferredScrollableViewportSize() {
Dimension size = super.getPreferredScrollableViewportSize();
size.setSize(new Dimension(0,0));
return size;
}
public ListView(ArrayList<System> items) {
DefaultListModel<System> list = new DefaultListModel<System>();
for (System item : items) {
list.addElement(item);
}
this.setSelectionModel(new DefaultListSelectionModel() {
boolean gestureStarted = false;
#Override
public void setSelectionInterval(int index0, int index1) {
gS = gestureStarted;
in0 = index0;
in1 = index1;
gestureStarted = true;
}
#Override
public void setValueIsAdjusting(boolean isAdjusting) {
if (!isAdjusting) {
gestureStarted = false;
}
}
});
ListSelectionModel selectionModel = this.getSelectionModel();
addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
point = e.getPoint();
isSelected = ActionHandler.mouseClickedPrebuild(point);
if(!gS && isSelected){
if (isSelectedIndex(in0)) {
selectionModel.removeSelectionInterval(in0, in1);
} else {
selectionModel.addSelectionInterval(in0, in1);
}
}
}
});
setModel(list);
setCellRenderer(new ListModelPrebuild());
}

How many times is getListCellRendererComponent called?

I'm trying to understand how getListCellRendererComponent method works but I don't get it. I made a separate class that extends BasicComboBoxRenderer and I added a counter which is printed every time getListCellRendererComponent is called. I then run a test class with a main method that shows a frame with just a JComboBox that uses my custom renderer class. This combobox has 3 items in total and I've set setMaximumRowCount(2) so it only shows 2 of them.
When I first run the program and the frame with the combobox appears, the counter informs that getListCellRendererComponent is called 6 times.
When the frame looses focus (when I click on my desktop for example) the method executes 1 time.
When the frame regains focus (click back on my frame) the method executes 1 time.
When I click on the arrow button and the drop-down list appears for the FIRST time, counter says that the method executes 8 times.
When I click again on the arrow button and the list disappears, the method is called 1 time (this happens always).
When I click on the arrow button AFTER the first time, the method is called 5 times.
When I click on the scrollbar button to go up or down, the method executes 1 time.
When I move the cursor on a not-selected item of the list, the method executes 2 times and after a second 1 more time (this is the most absurd)
When I click on an item of the list the method executes 4 times.
At first I thought that this method will be executed as many times as the number of the items in the list (plus one more that appears on the combobox display area).
But I can only understand one or two cases from the above, for example when I click the scrollbar buttons and the method executes 1 time, probably because a new item is rendered. The rest of them seem insane...

I would expect no less then n + 1 iterations of the renderer to be called at any one time.
The component needs to
Figure out the best size for the contents. This can be achieved by using a prototype value or, if none is specified, iterating through all the items to find the max bounds (thats 3 times)
Render the selected item if one exists +1 times
Render the list if the popup is visible +3 times
Possibly look for a tooltip
= a possible 7 iterations
When losing focus, the component needs to render the selected item +1
When regaining focus, the component will try a render te selected item again +1
When the popup is displayed, see the first part
The second time probably indicates that the component has cached the result of the first popup action (it's possible that the component is invalidating its internal cache between focus events)
Each time you change the view of the scrollpane, it needs to render any items not previously shown on the screen, this is done for optimisation reasons (imagine a lst with 100s of items, rendering all of them is a waste of time, hence the inclusion of the prototype value)
Mouse actions can be triggering a series of different actions, mouse in, mouse out, mouse move. Most likly these are to do with the tooltip manager and component trying to determine if a tooltip is available
Try setting a prototype value & see if that changes the number of iterations when the component displays its popup

I think that you forgot to describe how and which Object(s) you create or re_create in the Renderer,
you forgot to sent here your view about Renderer in the SSCCE form
then everything is in the academic level and too hard to write something about your Renderer ...
Renderer react to the every Mouse and Key events
plain Renderer with output from all important methods to the System.out.println("yyyy")
.
import java.awt.Component;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.plaf.basic.BasicComboBoxRenderer;
public class ComboBoxHoverOver {
private JComboBox combo = new JComboBox();
public ComboBoxHoverOver() {
combo.setPrototypeDisplayValue("XXXXXXXXXXXXXXXXXXXXXX");
combo.setRenderer(new ComboToolTipRenderer(combo));
combo.addItemListener(new ItemListener() {
#Override
public void itemStateChanged(ItemEvent e) {
System.out.println("itemStateChanged");
}
});
combo.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("actionPerformed");
}
});
combo.addItem("");
combo.addItem("Long text 4");
combo.addItem("Long text 3");
combo.addItem("Long text 2");
combo.addItem("Long text 1");
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(combo);
f.pack();
f.setVisible(true);
}
private class ComboToolTipRenderer extends BasicComboBoxRenderer {
private static final long serialVersionUID = 1L;
private JComboBox combo;
private JList comboList;
ComboToolTipRenderer(JComboBox combo) {
this.combo = combo;
}
#Override
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
System.out.println(value + ", " + index + ", " + isSelected + ", " + cellHasFocus);
if (comboList == null) {
comboList = list;
KeyAdapter listener = new KeyAdapter() {
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_DOWN || e.getKeyCode() == KeyEvent.VK_UP) {
int x = 5;
int y = comboList.indexToLocation(comboList.getSelectedIndex()).y;
System.out.println("keyReleased " + comboList.getSelectedIndex());
}
}
};
combo.addKeyListener(listener);
combo.getEditor().getEditorComponent().addKeyListener(listener);
comboList.addListSelectionListener(new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
if (e.getValueIsAdjusting()) {
JList list = (JList) e.getSource();
int item = list.getSelectedIndex();
if (item > -1) {
String string = list.getSelectedValue().toString();
System.out.println("valueChanged " + list.getSelectedValue().toString());
}
}
}
});
}
if (isSelected) {
System.out.println("isSelected " + value.toString());
}
return this;
}
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
ComboBoxHoverOver comboBoxHoverOver = new ComboBoxHoverOver();
}
});
}
}

Java Swing: JList with ListCellRenderer selected item different height

I'm making a custom ListCellRenderer. I know that you can have different dimensions for each individual cell. But now I want to have a different dimension for the selected cell. Somehow, the JList is caching the dimension for each individual cell the first time it has to calculate bounds for each cell.
This is my code:
public class Test {
static class Oh extends JPanel {
public Oh() {
setPreferredSize(new Dimension(100, 20));
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(), getHeight());
}
}
static class Yeah extends JPanel {
private boolean isSelected;
public Yeah(boolean isSelected) {
setPreferredSize(new Dimension(100, 100));
this.isSelected = isSelected;
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
//setSize(100, 100); // doesn't change the bounds of the component
//setBounds(0, 0, 100, 100); // this doesn't do any good either.
if (isSelected) g.setColor(Color.GREEN);
else g.setColor(Color.BLACK);
g.fillRect(0, 0, getWidth(), getHeight());
}
}
public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
f.setSize(800, 500);
Vector<Integer> ints = new Vector<Integer>();
for (int i = 0; i < 100; i++) {
ints.add(i);
}
JList list = new JList(ints);
list.setCellRenderer(new ListCellRenderer() {
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
if (isSelected || ((Integer) value) == 42) return new Yeah(isSelected);
else return new Oh();
}
});
//list.setPrototypeCellValue(null);
//list.setFixedCellHeight(-1);
f.add(new JScrollPane(list));
f.setVisible(true);
}
}
In the comments you can see what I've already tried.
I've already searched quite long and found a lot of useless articles, some of them touch the ListCellRenderer/dynamic height thing, but they only work because the height stays the same for the individual cells. My heights are changing, so how do I do this?

Basically, there are two aspects of the problem, both located in the ui delegate
it fails to configure the renderer to its real state when measuring, that is ignores the selection (and focus) completely
it is notoriously stubborn against being forced to re-calculate the cached cell sizes: it has no public api to do so and only does voluntarily on model changes.
The remedy to fix the first is indeed the renderer: implement to ignore the given selected flag and query the list for the real selection, as outlined by #Andy. In code, using the OP's components
ListCellRenderer renderer = new ListCellRenderer() {
Yeah yeah = new Yeah(false);
Oh oh = new Oh();
#Override
public Component getListCellRendererComponent(JList list,
Object value, int index, boolean isSelected,
boolean cellHasFocus) {
// ignore the given selection index, query the list instead
if (list != null) {
isSelected = list.isSelectedIndex(index);
}
if (isSelected || ((Integer) value) == 42) {
yeah.isSelected = isSelected;
return yeah;
}
return oh;
}
};
list.setCellRenderer(renderer);
To fix the second, a custom ui delegate (as suggested in others answers as well) is a possible solution. Though some work in the general case, if supporting multiple LAFs is needed.
A less intrusive but slightly dirty method to force the ui into voluntarily update its cache is to send a fake ListDataEvent on selectionChange:
ListSelectionListener l = new ListSelectionListener() {
ListDataEvent fake = new ListDataEvent(list, ListDataEvent.CONTENTS_CHANGED, -1, -1);
#Override
public void valueChanged(ListSelectionEvent e) {
JList list = (JList) e.getSource();
ListDataListener[] listeners = ((AbstractListModel) list.getModel())
.getListDataListeners();
for (ListDataListener l : listeners) {
if (l.getClass().getName().contains("ListUI")) {
l.contentsChanged(fake);
break;
}
}
}
};
list.addListSelectionListener(l);
BTW, JXList of the SwingX project has a custom ui delegate - mainly for supporting sorting/filtering - with public api to re-calculate the cache, then the above ListSelectionListener would be simplified (and clean :-) to
ListSelectionListener l = new ListSelectionListener() {
#Override
public void valueChanged(ListSelectionEvent e) {
((JXList) e.getSource()).invalidateCellSizeCache();
}
};
list.addListSelectionListener(l);

I just implemented this feature. The problem is, that the cell renderer is asked twice for rendering a cell. In the first round all list entries are rendered without selection, then the selected cells are rendered again using selection. So if you provide a preferred size in the first round, it is cached and also used for the second round.
The trick is to ignore the isSelected boolean parameter in the getListCellRendererComponent and to figure out the selection state by checking if list.getSelectedIndices() contains the given index.
But, I still have the problem, that after the list is made visible, the height of the rendered components are sometimes to large/small. After resizing the list by mouse everything is fine again. I played around with validate/revalidate, repaint, reset of cached heights, but nothing worked. Swing is sometimes a bit strange...

The JList has no ability to change size of cell depending on selection or whatever. The list use "cached" sizes. If there is new cellRenderer provided this sizes are recounted and applied within all cells in list. I think the reason is performance for list with a lot of entries. The possible solution is to write own ListUI implementation which is able to use different sizes for selected and unselected cells. This brings also possibility to adjust size of cells around selection by logarithm or other interpolation. I hope you have a big reason why to do this. It is a lot of work!

I've been tearing my hair out about this stupid JList row height problem.
I have a cell renderer which sets a variable row height for every row - problem is that JList keeps a cache of the heights.
Using the other answers, I think I've struck on the holy grail. Here it is:
Use a simplified version of the BasicListUI as created by Jaap:
public class BetterListUI extends BasicListUI {
public void triggerUpdate() {
updateLayoutState();
}
}
Then when you create a JList - extend it like this :
betterListUI = new BetterListUI();
myJList = new JList() {
#Override
public void repaint(long tm, int x, int y, int width, int height) {
betterListUI.triggerUpdate();
super.repaint(tm, x, y, width, height);
}
};
myJList.setUI(betterListUI);
You may need to put a guard around the triggerUpdate during creation depending on your circumstances.

Thanks to Rastislav Komara I've been able to solve this quite easily:
I've created an inner class that extends BasicListUI and created public method that is called on ListSelectionListener.valueChanged:
private class MyRenderer implements ListCellRenderer {
public int listSelectedIndex = -1;
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected,
boolean cellHasFocus) {
if (index == listSelectedIndex)
return new Yeah(isSelected);
else
return new Oh();
}
}
MyRenderer lcr = new MyRenderer();
private class MyListUI extends BasicListUI {
public void triggerUpdate() {
lcr.listSelectedIndex = list.getSelectedIndex();
updateLayoutState();
list.revalidate();
}
}
The updateLayoutState method is normally triggered when the JList height changes.
The only "insane" thing I'm doing here is that my renderer needs to know what the selected index is. This is because the updateLayoutState method doesn't use the selected index in it's height calculations.
Somehow using list.getSelectedIndex() inside getListCellRendererComponent doesn't work well.
Edit:
Check also the anser by nevster and kleopatra, they look way smarter, try them first...

The JList is probably "caching" your cell renderer. Try to attach a ListSelectionListener, and set the renderer again when selection is changed.
...
addListSelectionListener(new ListSelectionListener() {
public void valueChanged(ListSelectionEvent event) {
if(event.getValueIsAdjusting() == false) {
list.setCellRenderer(new MyRenderer());
}
}
)
...

this is a simple solution:
public class VariableHeightListUI extends BasicListUI {
#Override
public void paint(Graphics g, JComponent c) {
updateLayoutState();
super.paint(g, c);
}
}
of course you need write your own implementation of ListCellRenderer, and according to different selection state of list element, you can set different prefer height of returned Component.
Only one issue need to go on is : when you select an element of List FIRST time, not draw correctly. but after then, all work well.
hope this can help you.

JTable with a complex editor

I have many custom editors for a JTable and it's an understatement to say that the usability, particularly in regard to editing with the keyboard, is lacking.
The main reason for this is that my editors are always created with a similar (though often more complex) situation to this:
#Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
JPanel container = new JPanel();
container.setLayout(new BorderLayout());
container.add(field, BorderLayout.CENTER);
field.setText((String) value);
container.add(new JButton("..."), BorderLayout.EAST);
return container;
}
I.E a panel with more than one component inside. The actual text editor is a descendant of the component being returned as the editor.
So, rendering issues aside, from what I can tell, the JTable is focusing the component that is returned by the getTableCellEditorComponent method so when you press a key with a cell highlighted it passes focus and the key press to the panel, thinking that's the editor.
Is there anyway I can inform JTable that the "real" editor is the JTextfield?
Adding a hacky requestFocusInWindow on the correct component is insufficient as the key press won't get passed on.

If I read your question correctly, you want the user to be able to type into a cell immediately, without activating the cell editor first, i.e., you want whatever keystroke activated the cell to be the first character entered into the text field.
My first attempt was to add a propertyChangeListener on the focusOwner property of the KeyboardFocusManager, only to notice that the focus never leaves the JTable. You probably ran into that as well. Time for plan B.
I got that "first keypress" thing to work by adding a KeyListener to the table that records the last KeyEvent for the keyPressed() method in an instance field. The getTableCellEditorComponent() method reads the character from there. I also needed that hacky requestFocusInWindow() call you mention if the user is to keep typing any characters after the first one.
For my sample app, I created a subclass of JTable that adds a KeyListener to itself. It's a much better idea to make your CellEditor instance implement KeyListener and add that to the regular JTable instead, but I'll leave that to you.
Here's your code snippet as I modified it:
#Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
JPanel container = new JPanel();
container.setLayout(new BorderLayout());
container.add(field, BorderLayout.CENTER);
// Will want to add an instanceof check as well as a check on Character.isLetterOrDigit(char).
char keypressed = ((StickyKeypressTable)table).getLastKeyPressed();
field.setText(String.valueOf(keypressed));
container.add(new JButton("..."), BorderLayout.EAST);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
// This needs to be in an invokeLater() to work properly
field.requestFocusInWindow();
}
});
return container;
}
As far as nastiness goes this sits somewhere up there with Vogon Poetry, but it should solve your immediate problem.

I fixed something similar in 2 steps
First override the editCellAt from your JTable and call requestFocus after preparing the editor:
public boolean editCellAt( int row, int column, EventObject e )
{
if ( cellEditor != null && !cellEditor.stopCellEditing() )
{
return false;
}
if ( row < 0 || row >= getRowCount() ||
column < 0 || column >= getColumnCount() )
{
return false;
}
if ( !isCellEditable(row, column) )
return false;
TableCellEditor editor=getCellEditor(row, column);
if ( editor != null && editor.isCellEditable(e) )
{
editorComp=prepareEditor(editor, row, column);
if ( editorComp == null )
{
removeEditor();
return false;
}
//aangepast
Rectangle rect=getCellRect(row, column, false);
if ( datamodel_.useAdaptedEditorRect() )
rect=datamodel_.changeRectangle(rect, editorComp);
editorComp.setBounds(rect);
add(editorComp);
editorComp.validate();
setCellEditor(editor);
setEditingRow(row);
setEditingColumn(column);
editor.addCellEditorListener(this);
//NEXT LINE ADDED
editorComp.requestFocus();
return true;
}
return false;
}
Then overload the requestFocus from your JPanel and make sure your textfield is put as editorComponent:
public class EditorPanel extends JPanel {
JComponent editorComponent;
public boolean isRequestFocusEnabled()
{
return true;
}
public void requestFocus()
{
editorComponent.requestFocus();
}
}
You can always grab the keyEvent and set it yourself:
AWTEvent event = EventQueue.getCurrentEvent();
if ( event instanceof KeyEvent )
{
char newSelection = ( (KeyEvent) event).getKeyChar();
int keyCode = ( (KeyEvent) event ).getKeyCode();
editorComponent.requestFocus();
if ( editorComponent instanceof JTextField )
{
if ( ( newSelection >= (char) FIRST_ALLOWED_CHAR ) && ( newSelection != (char) LAST_ALLOWED_CHAR ) ) //comes from DefaultKeyTypedAction
( (JTextField) editorComponent ).setText(Character.toString(newSelection));
if ( keyCode == KeyEvent.VK_BACK_SPACE || keyCode == KeyEvent.VK_DELETE )
( (JTextField) editorComponent ).setText("");
}
}
else
editorComponent.requestFocus();

I think that I solved it.
To tell you the truth, I don't know what solved the problem, since I'm using a custom editor, a custom renderer and stuff...
When a cell is highlighted and I press "abc", the 3 letters go on screen (cell, in this case).
grid.addKeyListener(new KeyAdapter() {
public void keyTyped(KeyEvent ke) {
int l = grid.getSelectedRow();
int c = grid.getSelectedColumn();
grid.editCellAt(l, c);
}
});
Well... I tried... =)
(I don't know if it's the same because my JTable uses JTextField and JComboBox as editors).

I had very similar problem. In my case I had complex TableCellEditor which consists of JSpinner and some other components. The problem was that when cell editor started I wanted to transfer focus to its internal component. I fixed this by calling panel.transferFocusDownCycle() but this in turn caused keyboard events to stop working - when my internal component had focus and I pressed key up, I was expecting that component will intercept this event and change its value. Instead table changed row focus to one above... I fixed this by adding KeyListener and dispatching all key events directly to the internal component.
This is wrapper class based on JPanel I wrote to make my life easier.
public class ContainerPanel extends JPanel implements KeyListener, FocusListener {
private JComponent component = null;
public ContainerPanel(JComponent component) {
this.component = component;
addKeyListener(this);
addFocusListener(this);
setFocusCycleRoot(true);
setFocusTraversalPolicy(new ContainerOrderFocusTraversalPolicy());
add(component);
}
#Override
public void keyTyped(KeyEvent e) {
component.dispatchEvent(e);
}
#Override
public void keyPressed(KeyEvent e) {
component.dispatchEvent(e);
}
#Override
public void keyReleased(KeyEvent e) {
component.dispatchEvent(e);
}
#Override
public void focusGained(FocusEvent e) {
component.transferFocusDownCycle();
}
#Override
public void focusLost(FocusEvent e) {
}
}

How do I make a list with checkboxes in Java Swing?

What would be the best way to have a list of items with a checkbox each in Java Swing?
I.e. a JList with items that have some text and a checkbox each?

A wonderful answer is this CheckBoxList. It implements Telcontar's answer (though 3 years before :)... I'm using it in Java 1.6 with no problems. I've also added an addCheckbox method like this (surely could be shorter, haven't used Java in a while):
public void addCheckbox(JCheckBox checkBox) {
ListModel currentList = this.getModel();
JCheckBox[] newList = new JCheckBox[currentList.getSize() + 1];
for (int i = 0; i < currentList.getSize(); i++) {
newList[i] = (JCheckBox) currentList.getElementAt(i);
}
newList[newList.length - 1] = checkBox;
setListData(newList);
}
I tried out the demo for the Jidesoft stuff, playing with the CheckBoxList I encountered some problems (behaviors that didn't work). I'll modify this answer if I find problems with the CheckBoxList I linked to.

Create a custom ListCellRenderer and asign it to the JList.
This custom ListCellRenderer must return a JCheckbox in the implementantion of getListCellRendererComponent(...) method.
But this JCheckbox will not be editable, is a simple paint in the screen is up to you to choose when this JCheckbox must be 'ticked' or not,
For example, show it ticked when the row is selected (parameter isSelected), but this way the check status will no be mantained if the selection changes. Its better to show it checked consulting the data below the ListModel, but then is up to you to implement the method who changes the check status of the data, and notify the change to the JList to be repainted.
I Will post sample code later if you need it
ListCellRenderer

Just implement a ListCellRenderer
public class CheckboxListCellRenderer extends JCheckBox implements ListCellRenderer {
public Component getListCellRendererComponent(JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus) {
setComponentOrientation(list.getComponentOrientation());
setFont(list.getFont());
setBackground(list.getBackground());
setForeground(list.getForeground());
setSelected(isSelected);
setEnabled(list.isEnabled());
setText(value == null ? "" : value.toString());
return this;
}
}
and set the renderer
JList list = new JList();
list.setCellRenderer(new CheckboxListCellRenderer());
this will result in
Details at Custom swing component renderers.
PS: If you want radio elements just replace extends JCheckbox with extends JRadioButton.

I'd probably be looking to use a JTable rather than a JList and since the default rendering of a checkbox is rather ugly, I'd probably be looking to drop in a custom TableModel, CellRenderer and CellEditor to represent a boolean value. Of course, I would imagine this has been done a bajillion times already. Sun has good examples.

Better solution for Java 7 and newer
I stumbled upon this question and realized that some of the answers are pretty old and outdated. Nowadays, JList is generic and thus there are better solutions.
My solution of the generic JCheckBoxList:
import java.awt.Component;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.event.*;
#SuppressWarnings("serial")
public class JCheckBoxList extends JList<JCheckBox> {
protected static Border noFocusBorder = new EmptyBorder(1, 1, 1, 1);
public JCheckBoxList() {
setCellRenderer(new CellRenderer());
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
int index = locationToIndex(e.getPoint());
if (index != -1) {
JCheckBox checkbox = (JCheckBox) getModel().getElementAt(index);
checkbox.setSelected(!checkbox.isSelected());
repaint();
}
}
});
setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
}
public JCheckBoxList(ListModel<JCheckBox> model){
this();
setModel(model);
}
protected class CellRenderer implements ListCellRenderer<JCheckBox> {
public Component getListCellRendererComponent(
JList<? extends JCheckBox> list, JCheckBox value, int index,
boolean isSelected, boolean cellHasFocus) {
JCheckBox checkbox = value;
//Drawing checkbox, change the appearance here
checkbox.setBackground(isSelected ? getSelectionBackground()
: getBackground());
checkbox.setForeground(isSelected ? getSelectionForeground()
: getForeground());
checkbox.setEnabled(isEnabled());
checkbox.setFont(getFont());
checkbox.setFocusPainted(false);
checkbox.setBorderPainted(true);
checkbox.setBorder(isSelected ? UIManager
.getBorder("List.focusCellHighlightBorder") : noFocusBorder);
return checkbox;
}
}
}
For dynamically adding JCheckBox lists you need to create your own ListModel or add the DefaultListModel.
DefaultListModel<JCheckBox> model = new DefaultListModel<JCheckBox>();
JCheckBoxList checkBoxList = new JCheckBoxList(model);
The DefaultListModel are generic and thus you can use methods specified by JAVA 7 API here like this:
model.addElement(new JCheckBox("Checkbox1"));
model.addElement(new JCheckBox("Checkbox2"));
model.addElement(new JCheckBox("Checkbox3"));

I recommend you use a JPanel with a GridLayout of 1 column. Add the checkBoxes to the JPanel, and set the JPanel as the data source of a JScrollPane. And to get the selected CheckBoxes, just call the getComponents() of the JPanel to get the CheckBoxes.

Odds are good w/ Java that someone has already implemented the widget or utility you need. Part of the benefits of a large OSS community. No need to reinvent the wheel unless you really want to do it yourself. In this case it would be a good learning exercise in CellRenderers and Editors.
My project has had great success with JIDE. The component you want, a Check Box List, is in the JIDE Common Layer (which is OSS and hosted on java.net). The commercial stuff is good too, but you don't need it.
http://www.jidesoft.com/products/oss.htm
https://jide-oss.dev.java.net/

I don't like the solutions that put a Checkbox into the model. The model should only contain data not display elements.
I found this http://www.java2s.com/Tutorials/Java/Swing_How_to/JList/Create_JList_of_CheckBox.htm
which I optimized a bit. The ACTIVE flag represents the Checkbox, the SELECTED flag shows what entry the cursor sits on.
my version requires a renderer
import java.awt.Component;
import javax.swing.JCheckBox;
import javax.swing.JList;
import javax.swing.ListCellRenderer;
class CheckListRenderer extends JCheckBox implements ListCellRenderer<Entity> {
#Override
public Component getListCellRendererComponent(JList<? extends Entity> list,
Entity value, int index, boolean isSelected, boolean cellHasFocus) {
setEnabled(list.isEnabled());
setSelected(value.isActive()); // sets the checkbox
setFont(list.getFont());
if (isSelected) { // highlights the currently selected entry
setBackground(list.getSelectionBackground());
setForeground(list.getSelectionForeground());
} else {
setBackground(list.getBackground());
setForeground(list.getForeground());
}
setText(value.toString()+" - A" + value.isActive()+" - F"+cellHasFocus+" - S"+isSelected );
return this;
}
}
and an entity that got the active field:
public class Entity {
private boolean active = true;
public boolean isActive() {
return active;
}
public void setActive(boolean isActive) {
this.active = isActive;
}
}
Now you only have to add this to your JList:
list = new JList<Entity>();
list.setModel(new DefaultListModel<Entity>());
list.setCellRenderer(new CheckListRenderer());
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent event) {
if (event.getX() < 20) {
// Quick and dirty: only change the tick if clicked into the leftmost pixels
#SuppressWarnings("unchecked")
JList<Entity> list = ((JList<Entity>) event.getSource());
int index = list.locationToIndex(event.getPoint());// Get index of item clicked
if (index >= 0) {
Entity item = (Entity) list.getModel().getElementAt(index);
item.setActive(!item.isActive()); // Toggle selected state
list.repaint(list.getCellBounds(index, index));// Repaint cell
}
}
}
});

All of the aggregate components in Swing--that is, components made up other components, such as JTable, JTree, or JComboBox--can be highly customized. For example, a JTable component normally displays a grid of JLabel components, but it can also display JButtons, JTextFields, or even other JTables. Getting these aggregate components to display non-default objects is the easy part, however. Making them respond properly to keyboard and mouse events is a much harder task, due to Swing's separation of components into "renderers" and "editors." This separation was (in my opinion) a poor design choice and only serves to complicate matters when trying to extend Swing components.
To see what I mean, try enhancing Swing's JList component so that it displays checkboxes instead of labels. According to Swing philosophy, this task requires implementing two interfaces: ListCellRenderer (for drawing the checkboxes) and CellEditor (for handling keyboard and mouse events on the checkboxes). Implementing the ListCellRenderer interface is easy enough, but the CellEditor interface can be rather clumsy and hard to understand. In this particular case, I would suggest forgetting CellEditor entirely and to handle input events directly, as shown in the following code.
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
public class CheckBoxList extends JList
{
protected static Border noFocusBorder = new EmptyBorder(1, 1, 1, 1);
public CheckBoxList()
{
setCellRenderer(new CellRenderer());
addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
int index = locationToIndex(e.getPoint());
if (index != -1) {
JCheckBox checkbox = (JCheckBox)
getModel().getElementAt(index);
checkbox.setSelected(
!checkbox.isSelected());
repaint();
}
}
}
);
setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
}
protected class CellRenderer implements ListCellRenderer
{
public Component getListCellRendererComponent(
JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus)
{
JCheckBox checkbox = (JCheckBox) value;
checkbox.setBackground(isSelected ?
getSelectionBackground() : getBackground());
checkbox.setForeground(isSelected ?
getSelectionForeground() : getForeground());
checkbox.setEnabled(isEnabled());
checkbox.setFont(getFont());
checkbox.setFocusPainted(false);
checkbox.setBorderPainted(true);
checkbox.setBorder(isSelected ?
UIManager.getBorder(
"List.focusCellHighlightBorder") : noFocusBorder);
return checkbox;
}
}
}
Here, I intercept mouse clicks from the listbox and simulate a click on the appropriate checkbox. The result is a "CheckBoxList" component that is both simpler and smaller than an equivalent component using the CellEditor interface. To use the class, simply instantiate it, then pass it an array of JCheckBox objects (or subclasses of JCheckBox objects) by calling setListData. Note that the checkboxes in this component will not respond to keypresses (i.e. the spacebar), but you could always add your own key listener if needed.
Source: DevX.com

Here is just a little addition to the JCheckBoxList by Rawa. This will add the ability to select using space bar. If multiple items are selected, all will be set to inverted value of the first item.
addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
int index = getSelectedIndex();
if (index != -1 && e.getKeyCode() == KeyEvent.VK_SPACE) {
boolean newVal = !((JCheckBox) (getModel()
.getElementAt(index))).isSelected();
for (int i : getSelectedIndices()) {
JCheckBox checkbox = (JCheckBox) getModel()
.getElementAt(i);
checkbox.setSelected(newVal);
repaint();
}
}
}
});

this is yet another example of making list with checkboxes
class JCheckList<T> extends JList<T> {
protected static Border noFocusBorder = new EmptyBorder(1, 1, 1, 1);
public void setSelected(int index) {
if (index != -1) {
JCheckBox checkbox = (JCheckBox) getModel().getElementAt(index);
checkbox.setSelected(
!checkbox.isSelected());
repaint();
}
}
protected static class CellListener
extends DefaultListModel
implements ListDataListener {
ListModel ls;
public CellListener(ListModel ls) {
ls.addListDataListener(this);
int i = ls.getSize();
for (int v = 0; v < i; v++) {
var r = new JCheckBox();
r.setText(ls.getElementAt(v).toString());
this.addElement(r);
}
this.ls = ls;
}
#Override
public void intervalAdded(ListDataEvent e) {
int begin = e.getIndex0();
int end = e.getIndex1();
for (; begin <= end; begin++) {
var r = new JCheckBox();
r.setText(ls.getElementAt(begin).toString());
this.add(begin, r);
}
}
#Override
public void intervalRemoved(ListDataEvent e) {
int begin = e.getIndex0();
int end = e.getIndex1();
for (; begin <= end; end--) {
this.remove(begin);
}
}
#Override
public void contentsChanged(ListDataEvent e) {
}
}
public JCheckList() {
setCellRenderer(new CellRenderer());
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
int index = locationToIndex(e.getPoint());
setSelected(index);
}
}
);
addKeyListener(new KeyListener(){
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_SPACE){
int index = JCheckList.this.getSelectedIndex();
setSelected(index);
}
}
#Override
public void keyReleased(KeyEvent e) {
}
});
setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
}
#Override
public void setModel(ListModel<T> d) {
var r = new CellListener(d);
d.addListDataListener(r);
super.setModel(r);
}
protected class CellRenderer implements ListCellRenderer {
public Component getListCellRendererComponent(
JList list, Object value, int index,
boolean isSelected, boolean cellHasFocus) {
JCheckBox checkbox = (JCheckBox) value;
checkbox.setBackground(isSelected
? getSelectionBackground() : getBackground());
checkbox.setForeground(isSelected
? getSelectionForeground() : getForeground());
checkbox.setEnabled(isEnabled());
checkbox.setFont(getFont());
checkbox.setFocusPainted(false);
checkbox.setBorderPainted(true);
checkbox.setBorder(isSelected
? UIManager.getBorder(
"List.focusCellHighlightBorder") : noFocusBorder);
return checkbox;
}
}
}