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Disable button in Java until all fields filled

I'm new to Java and developing a small project. I'm making a program where the user has to register themselves. I have 3 different tabs on my Tabbed Pane. I want to be able to disable the next button on the first pane making it impossible for the user to continue to pane 2 unless all the text fields on pane 1 have been filled. I have been Searching online and found various examples but none of them would work in run time.
I am using Netbeans.
private void txtFirstNameActionPerformed(java.awt.event.ActionEvent evt) {
if(txtFirstName.getText().trim().length() > 0)
btnNext1.setEnabled(true);
else
btnNext1.setEnabled(false);
}

Create a List of all the text fields on your pane:
List<JTextField> list = new ArrayList<>();
Add all your text fields to that list.
Then, create a universal DocumentListener that listens for text change events, and every time a text update happens, scan through all your text fields to see if they have all been filled:
DocumentListener listener = new DocumentListener() {
#Override
public void removeUpdate(DocumentEvent e) { changedUpdate(e); }
#Override
public void insertUpdate(DocumentEvent e) { changedUpdate(e); }
#Override
public void changedUpdate(DocumentEvent e) {
boolean canEnable = true;
for (JTextField tf : list) {
if (tf.getText().isEmpty()) {
canEnable = false;
}
}
btnNext1.setEnabled(canEnable);
}
};
And add that listener to every text field you have in the list:
for (JTextField tf : list) {
tf.getDocument().addDocumentListener(piecesListener);
}

JPopupMenu not showing text of JMenuItem

I'm trying to create a JPopupMenu, but for some reason, it doesn't show the text I've set on the JMenuItems. The menu itself works, there are menuitems in it and they are responsive, but the text is not showing. I'm creating the menu like this:
private void createPopupMenu() {
this.popupMenu = new JPopupMenu();
this.addMouseListener(new PopupListener(this));
JMenuItem addPlaceMenuItem = new JMenuItem(SketchPad.ADD_PLACE_POPUP_TEXT);
addPlaceMenuItem.setAction(new PopupAction(ActionType.AddPlace));
this.popupMenu.add(addPlaceMenuItem);
JMenuItem addTransitionMenuItem = new JMenuItem(SketchPad.ADD_TRANSITION_POPUP_TEXT);
addTransitionMenuItem.setAction(new PopupAction(ActionType.AddTransition));
this.popupMenu.add(addTransitionMenuItem);
}
In case it matters, here is the PopupListener:
class PopupListener extends MouseAdapter {
SketchPad pad;
public PopupListener(SketchPad pad)
{
this.pad = pad;
}
public void mousePressed(MouseEvent e) {
maybeShowPopup(e);
}
public void mouseReleased(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1)
{
this.pad.getController().deselectAllNodes();
}
else
{
maybeShowPopup(e);
}
}
private void maybeShowPopup(MouseEvent e) {
if (e.isPopupTrigger()) {
pad.popupPosition = new Point(e.getX(), e.getY());
pad.popupMenu.show(e.getComponent(), e.getX(), e.getY());
}
}
}
What am I missing here?

but for some reason, it doesn't show the text I've set on the JMenuItems.
addPlaceMenuItem.setAction(new PopupAction(ActionType.AddPlace));
The setAction(...) method reset the properties of the menu item with the properties of the Action. So you need to make sure you set the NAME property of the Action to set the text of the menu item.
So in your case it looks like the value of the NAME property should be:
SketchPad.ADD_PLACE_POPUP_TEXT
Or the other approach is to reset the text of the menu item after you set the Action
JMenuItem addPlaceMenuItem = new JMenuItem( new PopupAction(ActionType.AddPlace) );
addPlaceMenuItem.setText(SketchPad.ADD_PLACE_POPUP_TEXT);

The effect is platform specific. In particular, "In Microsoft Windows, the user by convention brings up a popup menu by releasing the right mouse button while the cursor is over a component that is popup-enabled." Your implementation of mouseReleased() precludes even checking isPopupTrigger(). Instead, handle the selection and check the trigger. A similar approach is shown in GraphPanel in order to handle multiple selection and a context menu.

Custom JComboBox hiding JPopupMenu

I'm having a little headache with a situation. Maybe some of you have been through this before and can show me another way or even my error here.
I need to add a JTree inside a JComboBox and the code below works like a charm.
public class HierarchyComboBox extends JComboBox {
HierarchyTree ht = new HierarchyTree();
HierarchyComboBox box;
JPopupMenu popup;
MouseAdapter adapter = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent arg0) {
if (arg0.getClickCount() == 1) {
removeAllItems();
addItem(ht.getSelectedLevel());
// ((JPopupMenu) comp).setVisible(false);
}
}
};
PopupMenuListener listener = new PopupMenuListener() {
#Override
public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
if (box == null) {
box = (HierarchyComboBox) e.getSource();
if (popup == null) {
final Object comp = box.getUI().getAccessibleChild(box, 0);
if (!(comp instanceof JPopupMenu))
return;
popup = (JPopupMenu) comp;
}
popup.removeAll();
ht.getTreePane().setBorder(null);
ht.getTreePane().setPreferredSize(new Dimension(box.getWidth(), 200));
MyTree tree = (MyTree)ht.getTreePane().getViewport().getComponent(0);
tree.addMouseListener(adapter);
popup.add(ht.getTreePane());
}
}
#Override
public void popupMenuCanceled(PopupMenuEvent arg0) { }
#Override
public void popupMenuWillBecomeInvisible(PopupMenuEvent arg0) { }
};
public HierarchyComboBox() {
setEditable(true);
addPopupMenuListener(listener);
}
}
but I added this component to 2 different dialogs.
The first one I can click and the selection is added to the JComboBox
and the second, doing EXACTLY the same instantiation, and the same tests
The component has a different behaviour:
- The JPopupMenu disappears
- It doesn't add the selection to the combo
Any ideas here?
Thanks in advance..

As shown in Providing a Custom Renderer, "A combo box uses a renderer to display each item in its menu." You could render the tree in a custom ListCellRenderer. Alternatively,
Render the tree in an adjacent component in response to an ActionListener.
Use a hierarchical model, shown here.

I noticed that the JPopupMenu was loosing it's focus.
The solution was to add the component as the last component of the Panel.

How to "ignore/discard" Swing UI events when doing data validations on UI?

There's a text field and when lost focus it will validate the inputs, if not passed, print out the error message (to be simple here just has an empty check). And there's a button next to the text field, it will print out the text once click on it.
As I tried, when input some text and then click the button it will trigger both the focus lost event of text field and the event of button. In a other word, it will do the validation first and then print out the input text.
Here comes my question, what is the good approach to prevent printing out the text if the validation not passed? Or is there a way to "ignore" the click event on button if validation not passed?
I tried to use a boolean flag which indicate the validation result and check the flag when perform the action for button, but I do not think it is a good approach. As I know there's an event dispatcher thread in Swing which deal with the events, is it possible I can cancel the events from here?
Below is a piece of code which explain the question:
public class SimpleDemo
{
public static void main(String[] args)
{
JFrame frame = new JFrame("Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel content = new JPanel(new FlowLayout());
frame.setContentPane(content);
final JTextField textField = new JTextField(10);
textField.addFocusListener(new FocusAdapter()
{
#Override
public void focusLost(FocusEvent e)
{
String text = textField.getText();
// do some validation here, if not validated
// do not trigger the event on button.
if ("".equals(text))
{
System.out.print("please input a text!");
}
}
});
content.add(textField);
JButton button = new JButton("Print Text");
button.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
// action performed for button
String text = textField.getText();
System.out.println(text);
}
});
content.add(button);
frame.setVisible(true);
frame.pack();
}
}

I faces similar issue while working on an application. I solved it like below
I created a abstract class ApplicationFrame which every frame in the application extends
public abstract class ApplicationFrame extends JFrame implements ActionListener {
#Override
final public void actionPerformed(ActionEvent event) {
if(validateInput()){
performAction(event);
}
}
/*
* Sub class should override this method to receive any action
*/
protected void performAction(ActionEvent event) {};
/*
* Sub class should override this method to perform validation
*/
abstract protected boolean validateInput();
}
All Frames will now extend this base frame, as below:
public class Frame1 extends ApplicationFrame{
#Override
protected void performAction(ActionEvent event) {
// perform action
}
#Override
protected boolean validateInput() {
// return true or false depending upon the validation results
}
// if you want to add Action Listener, you need to add like this:
btnSomeButton.addActionListener(this);
}
If you need to handle Focus events, you can make ApplicationFrame or the base frame implement FocusListener.
This is my custom implementation to solve the problem, hope this helps.

Make the button disabled on start-up
Upon lost focus, validate the text & enable button only when the input passes validation.
Upon start of text change, disable the button

It's always makes sense to make ui to communicate with user. So you can show "please input a text" as the default text of the textField when nothing is entered by user.
Here is the code for such custom textField:
public class TextFieldWithDefaultText extends JTextField implements FocusListener{
private final String hint;
public TextFieldWithDefaultText (String $text)
{
super($text);
this.hint = $text;
addFocusListener(this);
}
#Override
public void focusGained (FocusEvent $e)
{
if (this.getText().isEmpty())
{
super.setText("");
}
}
#Override
public void focusLost (FocusEvent $e)
{
if (this.getText().isEmpty())
{
super.setText(hint);
}
}
#Override
public String getText ()
{
String typed = super.getText();
return typed.equals(hint) ? "" : typed;
}
}
Write the acttionListerner for your button like this:
JButton button = new JButton("Print Text");
button.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
if(!textField.getText().isEmpty())
System.out.println(textField.getText());
}
});
And ur textField implementation should be :
final TextFieldWithDefaultText textField = new TextFieldWithDefaultText ("please input a text");
Hope this helps :)

JLabel on change text event

How I can retrive the event on a JLabel when change the text inside??
I have a JLabel and when change the text inside I have to update other field.

techically, the answer is to use a PropertyChangeListener and listen to changes of the "text" property, something like
PropertyChangeListener l = new PropertyChangeListener() {
public void propertyChanged(PropertyChangeEvent e) {
// do stuff here
}
};
label.addPropertyChangeListener("text", l);
not so technically: could be worth to re-visit the overall design and bind to original source which triggered the change in the label

IMHO you can not get an event on JLabels textchange. But you can use a JTextField instead of a JLabel:
private JTextField textFieldLabel = new JTextField();
textFieldLabel.setEditable(false);
textFieldLabel.setOpaque(true);
textFieldLabel.setBorder(null);
textFieldLabel.getDocument().addDocumentListener(new DocumentListener() {
public void removeUpdate(DocumentEvent e) {
System.out.println("removeUpdate");
}
public void insertUpdate(DocumentEvent e) {
System.out.println("insertUpdate");
}
public void changedUpdate(DocumentEvent e) {
System.out.println("changedUpdate");
}
});
Note: this event is fired no matter how the text gets changed; programatically via "setText()" on the TextField or (if you do not "setEditable(false)") via clipboard cut/paste, or by the user typing directly into the field on the UI.
The lines:
textFieldLabel.setEditable(false);
textFieldLabel.setOpaque(true);
textFieldLabel.setBorder(null);
are used to make the JTextField look like an JLabel.