Develop Reference

How to avoid Multiple Jbutton selections

I am using Jbuttons for a game called who wants to be a zillionaire in an assignment. I am using the buttons for selecting an answer. Here is the code for some of the buttons. Code:
}
});
Answer2.setBounds(220, 105, 188, 25);
panel.add(Answer2);
Answer1 = new JButton("A");
Answer1.setBackground(Color.YELLOW);
Answer1.setHorizontalAlignment(SwingConstants.LEFT);
Answer1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Answer1.setBackground(Color.BLUE);
Answer1.setForeground(Color.WHITE);
}
});
Answer1.setBounds(20, 105, 188, 25);
panel.add(Answer1);
Answer4 = new JButton("D");
Answer4.setBackground(Color.YELLOW);
Answer4.setHorizontalAlignment(SwingConstants.LEFT);
Answer4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Answer4.setBackground(Color.BLUE);
Answer4.setForeground(Color.WHITE);
}
});
At the moment multiple buttons can be selected and I wish to prevent this. It would be helpful if you could show me an example of code that could be used to do this.

Use the setEnable() method to make unwanted buttons disable or make a Boolean class level variable and make it true when the desired button is clicked. Then before invoking other buttons' algorithms simply check whether this variable's value is true.
Edited
public class YourClassName{
static boolean isAnswerSelected = false;
//your codes goes here
Answer1.setHorizontalAlignment(SwingConstants.LEFT);
Answer1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(!isAnswerSelected){ //this line will check whether an answer is already selected
isAnswerSelected = true; // this will make other answers unselectable
Answer1.setBackground(Color.BLUE);
Answer1.setForeground(Color.WHITE);
}
}
});
}
Use the above if statement and isAnswerSelected = true; line for all your actionPerformed() methods for all buttons.

Java how to assign id to button and retrieve them?

I'm getting stuck while building a forum like application which has a vote button.
I have vote up and vote down button for each content which are automatically generated. I want this button to only display the up and down arrow but not any text or label.. how can i find out which button is pressed?
Automated content..
ImageIcon upvote = new ImageIcon(getClass().getResource("vote_up.png"));
ImageIcon downvote = new ImageIcon(getClass().getResource("vote_down.png"));
JButton vote_up = new JButton(upvote);
JButton vote_down = new JButton(downvote);
vote_up.addActionListener(voting);
vote_down.addActionListener(voting);
Action voting = new AbstractAction(){
#Override
public void actionPerformed(ActionEvent e){
//What to do here to find out which button is pressed?
}
};
any help is appreciated.
public void a(){
int crt_cnt = 0;
for(ClassA temp : listofClassA)
{
b(crt_cnt);
crt_cnt++;
}
}
public void b(crt_cnt){
//draw button
}
As from above, I have multiple vote_up and vote_down button created by the b function, how can i differentiate which crt_cnt is the button from?

There are multiple ways you might achieve this
You could...
Simply use the source of the ActionEvent
Action voting = new AbstractAction(){
#Override
public void actionPerformed(ActionEvent e){
if (e.getSource() == vote_up) {
//...
} else if (...) {
//...
}
}
};
This might be okay if you have a reference to the original buttons
You could...
Assign a actionCommand to each button
JButton vote_up = new JButton(upvote);
vote_up.setActionCommand("vote.up");
JButton vote_down = new JButton(downvote);
vote_down .setActionCommand("vote.down");
//...
Action voting = new AbstractAction(){
#Override
public void actionPerformed(ActionEvent e){
if ("vote.up".equals(e.getActionCommand())) {
//...
} else if (...) {
//...
}
}
};
You could...
Take full advantage of the Action API and make indiviual, self contained actions for each button...
public class VoteUpAction extends AbstractAction {
public VoteUpAction() {
putValue(SMALL_ICON, new ImageIcon(getClass().getResource("vote_up.png")));
}
#Override
public void actionPerformed(ActionEvent e) {
// Specific action for up vote
}
}
Then you could simply use
JButton vote_up = new JButton(new VoteUpAction());
//...
Which will configure the button according to the properties of the Action and will trigger it's actionPerformed method when the button is triggered. This way, you know 100% what you should/need to do when the actionPerformed method is called, without any doubts.
Have a closer look at How to Use Actions for more details

You can detect by using the method getSource() of your EventAction
Action voting = new AbstractAction(){
#Override
public void actionPerformed(ActionEvent e){
if (e.getSource() == vote_up ) {
// vote up clicked
} else if (e.getSource() == vote_down){
// vote down clicked
}
}
};

hey thanks for all the help and assistance! I've finally got it! I solved it by
assigning a text on the button, +/- for vote up or down, followed by the content id which i required, then change the font size to 0
vote.setText("+"+thistopic.content.get(crt_cnt).get_id());
vote.setFont(heading.getFont().deriveFont(0.0f));
after that i could easily trace which button is pressed by comparing to the
actionEvent.getActionCommand()
which return the text on the button!

I would wrap the JButton similar to this:
JButton createMyButton(final JPanel panel, final String text,
final boolean upOrDown, final int gridx, final int gridy) {
final JButton button = new JButton();
button.setPreferredSize(new Dimension(80, 50));
final GridBagConstraints gbc = Factories.createGridBagConstraints(gridx,
gridy);
panel.add(button, gbc);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(final ActionEvent e) {
myActionPerformed(text, upOrDown);
}
});
return button;
}
You could use an int instead of the text, if more convenient.

Identifying which button was pressed

I'm trying to build a GUI which has a lot of buttons(JButton)/dropdown items (JMenuItem) and when each button containing letters is pressed the associated letter is being added to a label.
I'm having trouble identifying which button was pressed.Can you please give me a tip on how to do this?
Code:
private void dodajCrko(java.awt.event.ActionEvent evt) {
jlStatus.setText(jlStatus.getText() + evt.getSource()/* what to add here?*/);
}

I would use the getActionCommand() method:
private void dodajCrko(java.awt.event.ActionEvent evt) {
jlStatus.setText(jlStatus.getText() + actionEvent.getActionCommand());
}

I think you need this
((Button)actionEvent.getSource()).getLabel()
This will give you the label of the button clicked. You need to type cast the Source to Button like (Button)actionEvent.getSource()
Your code should be
private void dodajCrko(java.awt.event.ActionEvent evt) {
jlStatus.setText(jlStatus.getText() +
((Button)actionEvent.getSource()).getLabel());
}
As #Anto said, You should use actionEvent.getActionCommand() if you use any toggle buttons because the command string would identify the intended action.

In my opinion i find this works better.
private JButton button1;
Then use this.
button1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.out.println("Button 1 was presseed");
}
});
Hope this helps, Luke.

Mouse Click on JTable

I have a bunch of code that displays data in a Grid using Jtable. I need to capture the mouse double click event. But some how this simple code is just working on the Header of the grid but not working on the rows of that that Grid. Any clue? One more thing, the grid is editable as well.
Thank you.
Regards.
Manish

Some of your code would be helpful. Are you doing something similar to this?
table.getTableHeader().addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent event) {
if (e.getClickCount() == 2 && !e.isConsumed()) {
e.consume();
// handle double click here
}
});

you can do it as
class ButtonEditor extends DefaultCellEditor {
protected JButton button;
private String label;
private boolean isPushed;
public ButtonEditor(JCheckBox checkBox) {
super(checkBox);
button = new JButton();
button.setOpaque(true);
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
fireEditingStopped();
}
});
}
here you can provide any component instead of button.
refer full example

Java Swing: Focus issue

I'm making a level editor for my game. I have a property panel where I can modify the selected object its properties. I also have a Save button to write the level xml.
A field-edit is submitted(*) when the editor component lost the focus or Enter is pressed. This is working great, but the only problem is that when I have this sequence of actions:
Edit a field
Press the save button
Because, what happens is this:
I edit the field
I press the save button
The level is saved
The field lost the focus
The edit is submitted
As you can see, this is the wrong order. Of course I want the field to lose its focus, which causes the submit and then save the level.
Is there a trick, hack or workaround to make the field first lose the focus and then perform the action listener of the save button?
Thanks in advance.
(* submit = the edit to the field is also made in the object property)
EDIT: For the field I'm using a FocusAdapter with focusLost:
FocusAdapter focusAdapter = new FocusAdapter()
{
#Override
public void focusLost(FocusEvent e)
{
compProperties.setProperty(i, getColor());
record(); // For undo-redo mechanism
}
};
And for the button a simple ActionListener with actionPerformed`.
btnSave.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
// Save the level
}
});

Hmm ... can't reproduce: in the snippet below the lost is always notified before the actionPerfomed, independent on whether I click the button or use the mnemonic:
final JTextField field = new JTextField("some text to change");
FocusAdapter focus = new FocusAdapter() {
#Override
public void focusLost(FocusEvent e) {
LOG.info("lost: " + field.getText());
}
};
field.addFocusListener(focus);
Action save = new AbstractAction("save") {
#Override
public void actionPerformed(ActionEvent e) {
LOG.info("save: " + field.getText());
}
};
save.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_S);
JButton button = new JButton(save);
JComponent box = Box.createHorizontalBox();
box.add(field);
box.add(button);
On the other hand, focus is a tricky property to rely on, the ordering might be system-dependent (mine is win vista). Check how the snippet behave on yours.
If you see the same sequence as I do, the problem is somewhere else
if you get the save before the lost, try to wrap the the save action into invokeLater (which puts it at the end of the EventQueue, so it's executed after all pending events)
Action save = new AbstractAction("save") {
#Override
public void actionPerformed(ActionEvent e) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
LOG.info("save: " + field.getText());
}
});
}
};

Normally, wrapping your save code into an SwingUtilities.invokeLater() should do the trick. As you already mentioned, this doesn't work? Try this:
private boolean editFocus = false;
FocusAdapter focusAdapter = new FocusAdapter()
{
#Override
public void focusGained(FocusEvent e){
editFocus = true;
}
#Override
public void focusLost(FocusEvent e){
compProperties.setProperty(i, getColor());
record(); // For undo-redo mechanism
editFocus = false;
if (saveRequested){
save();
}
}
};
and for your button:
private boolean saveRequested = false;
btnSave.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
if (editFocus){
saveRequested = true;
return;
} else {
save();
}
}
});
and then your save method:
private void save(){
// do your saving work
saveRequested = false;
}
This only works when your focusLost gets called after your button's action. If suddenly the order is correct, this code will get save() called twice.
But again, wrapping your save() code in your original approach should work, because the save code will execute after processing all events. That is after processing your button click and your focusLost events. Because your focusLost code executes immediately (it's not wrapped in an invokeLater()), the focusLost code should be executed always before your save code. This does not mean that the event order will be correct! But the code associated to the events will executed in the right order.