Develop Reference

Clear key listeners from JPanel

I have created java swing application. In that application, there is a textfield.I have attached key listner for that text field also. Using that, enter key is identified and popup another JPanel. There is a JTable which is loaded data from DB and there is a JButton. The selected row from that table is loaded to that previous textfield.
There is a very rare issue with that implementation. when we have that JPanel, mistakenly the user pressed the enter button twice in very very short period at once. Then after we load that panel ther is a unusal behavior. by default the JButton is pressed without any key pressed.
According to my investigation, the problem can be solved, if we have a method to cler keylistner actions once it finished.
Are ther any methods?

To detect the paste event in addressbar in gwt

How to detect that pasting event is fired in the address bar through GWT? When we paste the thing from textbox to the addressbar then how to detect that pasting event in gwt.

What if a user decides to type an address instead of pasting it?
A standard approach is to use OnValueChangeEvent on a Textbox. It fires when a Textbox loses focus AND a value in the Textbox has changed, or when the Enter button is pressed while focus is still on the Textbox.
An alternative approach is to add a button, like "Take me there", that a user can press after a user is done entering the URL (either by pasting it or typing it).

How to exit from Java Swing application, avoiding messages generated from setInputVerifier

I have a text field where I have imposed some constraint in input data, by the help of InputVerifier.
The constraint is if the text field is left empty, then an error message will pop up. When the application starts, the cursor remains on the text field (text_field.requestFocusInWindow()).
Now, If the exit button is clicked, at anytime, The application should terminate immediately. But if the text field remains empty, it displays the error message and doesn't exit. How to solve this problem?
Exit Code:
dispose();
System.exit(0);

Ok, let's say your textfield is in a JFrame. Then register a WindowEventListener on the frame. Catch the event that closes the window and remove the InputVerifiers from all textfields. Then call System.exit().

Postpone Event Queue after Focus Lost

I have a JTable with a custom cell editor. The editor implements FocusListener so I can check if the cell's contents is valid if the user clicks away from the cell.
I'd like to use a JOptionPane within focusLost (in the EventDispatchThread) to allow the user to select whether to revert to an old value or accept an adjusted value.
Here's the problem; if the user is editing a cell, then clicks a button away from the table, the button's actionlisteners are alerted before JOptionPane has returned.
This is what I'd like to happen:
User edits cell
User clicks button
Cell detects focus lost
JOptionPane displayed and user selects action
JOptionPane closes and cell's value set
Button's actionListeners called
Instead, this is happening:
User edits cell
User clicks button
Cell detects focus lost
JOptionPane displayed and user selects action
Button's actionListeners called
JOptionPane closes and cell's value set
Is it possible to postpone the button's action events until after the JOptionPane has closed?
From other threads, I've read that JDialog does some magic to ensure event dispatching continues so the Dialog itself can handle events.

From what I gather, you don't want the button's action-listener to activate at all, until AFTER the user selects the correct value from the JOptionPane.
To me it seems like the solution would be to set up a 'disabled' flag which goes up once the focusLost is triggered. Once the selection is made, the disabled flag goes down. When the button action is triggered, it checks if the form is disabled; if it is, it does nothing. If it isn't it continues as normal.
Notice the button event won't go automatically once the user selected something in the JOptionPane, but instead he will have to click the button again. To me this seems like better functionality then having the button 'clicked' again for him after he is required to change the form.

Put your validation logic inside TableCellEditor#stopCellEditing(), showing your dialog and returning false if the value is not valid.
To automatically stop table editing on focus lost, use table.putClientProperty("terminateEditOnFocusLost", true);, but I don't think that will stop the buttons action listener from running. Instead I usually stop the table edit in the actionPerformed and do nothing when false is returned (or cancel editing when appropriate, for example if the action is to delete that table row).

Swing Events Trouble

I am new to Java and am developing a java swing application.
The main frame (JFrame) has a text box and an OK button. There is some long processing to be done when the focus from the text box is lost as well as different long processing when the OK button is clicked. Now if the user enters a value in the text box and clicks the OK button directly, ideally, first the focus lost event is fired and then the event on the OK button. The problem is that while the focus lost event is running a joption frame comes up asking the user for some input, but even before user enters the input here, the OK button event starts executing leading to problems in the application. How can I serialize the event calls.
Any help will be appreciated.

Your problem lies within the concept of the Event Dispatch Thread. For long running work loads, check out the SwingWorker class.