What I want to do is, when my Edit JMenu is clicked on, before it appears I want to set enabled on the undo / redo commands based on whether or not they should be visible.
Is there a way to get such a notification? Is MenuListener what I'm looking for?
You should be able to use a MenuListener, an extended EventListener, and enable the undo/redo items in menuSelected.
Now that I think about it, that probably would've been a better way for me to have done something very similar. I instead enabled/disabled the items in an undo/redo method in my view when my history object reported that there were no more undo/redo commands left.
EDIT: I see you must've quickly edited your post before I had the chance to post this and found MenuListener yourself.
Related
I see there are methods already built for adding and removing mouse listeners, I suppose I could add them and remove them as needed. I just wasn't sure if there was a better way.
Having my JLabel respond to all mouse events over it but sometimes do nothing isn't quite what I'm looking for, it would be nice if my Labels had the mouse listener only when I needed it to. Maybe this whole idea is just a weird approach.
You register the Listener once and for all; you don't turn it off and on.
You can code logic inside to only take action under certain conditions of your choosing. As long as you make the information available that's needed for a decision your implementation should be fine.
I'm a novice Android monkey and I've hit a snag trying to implement a feature on my app. What I want to do is have my users be able to long click an overlay item (it's a bus stop) and add that marker (stop number and address) to their favorites tab. The problem is... how do I listen for and handle a long click(tap) on an overlay item??
Currently I'm #overriding the onTap function in my Overlay class to handle regular taps, but I don't see an onLongTap function to override in the documentation... Can anyone set me along the right path? Am I missing something obvious here? Thanks for reading this
P.S. This is my first SO question :-)
You probably want to override onTouchEvent(MotionEvent, MapView) for more complex user interactions. For a 'long' tap, you should start some sort of timer that will indicate how long the user has been pressing on a specific Overlay item. Once a certain threshold is reached - I believe the default delay for a 'long' press is roughly 1500 ms - you then execute the relevant code.
Alternatively, you could take a look at including the mapview-overlay-manager project, which, from the reads of it, should offer exactly what your looking for (and then some):
OnOverlayGestureListener
Simplified OnGestureListener. A ManagedOverlayer uses its own build-in GestureDetector that fires
events like:
onSingleTap(MotionEvent, ManagedOverlay, GeoPoint, OverlayItem)
onDoubleTap(MotionEvent, ManagedOverlay, GeoPoint, OverlayItem)
onLongPress(MotionEvent, ManagedOverlay, GeoPoint, OverlayItem)
onZoom(ZoomEvent, ManagedOverlay) onScrolled(...)
I have a JTable where I can select one or more cells. I also want to react on double-click for doing some extra action for the selected cells. But the problem is, when the user double-clicks, the selection changes to the clicked cell. But I want to keep the prior selection on double-click, so I can handle the double-click for all selected cells.
EDIT:
Related to this question:
Java : ignore single click on double click?
But I hope, there is a better/easier solution for my case.
The problem is, that on the first click the first event goes out. A bit later the second click might come or not. So the first click event does know nothing. As in the proposed solution a timer might do.
What also might do is on the first click to select nothing, but invoke a special selection event a bit later.
SwingUtilities.invokeLater(myRunnable);
and on handling the double click/myRunnable the true selection. Timing might be unavoidable though.
you can use setClickCountToStart() for XxxCellEditor, I don't know something about your JTable
I have a general question regarding listeners.
Lets say I have two JTabbedPanes and both have a ChangeListener. They are both displayed and I want them both to show the same pane (index) so when a user changes the selected pane in one the other changes too.
In brief, one JTabbedPane listener changes the other JTabbedPane using setSelectedTab().
Obviously, the first listener will activate the second listener and the second will reactivate the first in an endless operation.
This will be solved with booleans.
Is there a smarter way to do it?
Is there a way to change a tab without triggering the Listener?
Is there a way to activate the listener only when a user changes it and not the code?
Thank you.
BTW: I always have the same questions with buttons. But with buttons I take the code from the listener and put it in a method. when One button needs to activate a button it calls its code. But in JTabbedPane it is different.
The simple solution is to act only when necessary. For example:
if(currentTab != desiredTab) {
// change tab
}
That will prevent an infinite loop.
If you need to be able to switch the behavior on and off, then using a boolean flag isn't a bad way to go about it. The alternative is the remove the listener, using removeChangeListener. The flag may be more performant as it may avoid memory allocation and deallocation, but a lot depends on the other details of your situation.
share the selectionModel, like
secondTabbedPane.setModel(otherTabbedPane.getModel());
I am working on a project that is using a JTable to display, among other things, a column of dates. We needed validation for the user input for dates, so I have implemented a combination of masking for format validation and parsing for actual date validation. I have done this using a custom CellEditor for the date column.
Inside my MaskedCellEditor, I have a JFormattedTextField. I setup the masking for dates. Then I add an InputVerifier to allow for actual validation. My InputVerifier implements verify() to check: 1. textField.isEditValid() 2. DateValidator.ValidDate(). If either is invalid, verify returns false and the InputVerifier locks the focus into the text field (the cell editor) and a small message dialog is displayed reminding the user of the date format.
The error message is a small, undecorated, non-modal, non-focusable JDialog that pops up underneath the cell being edited. It disappears on a keypress or a successful date verification. It is working great except for a small edge case.
If the user selects a menu button on the top of the application while an invalid edit has popped up the dialog, it switches screens, destroying everything currently on the screen (including the table). However, since the dialog is being shown and a keypress/successful edit has not occurred, the dialog is never hidden. It remains visible in a completely unrelated context on a different screen. Once the user has switched off the screen with the table, there is no way for the user to get rid of the dialog.
I have debated throwing either a Timer and/or a MouseListener on the dialog itself that would cause it to disappear, but I feel that I am ignoring the actual problem. The dialog is never being disposed of and I am pretty sure its because it is still set to be visible and it is preventing the garbage collector from getting rid of it.
I have a Cleanup method on the panel holding the JTable, but I cannot find a good way to reference the dialog (a component of the InputVerifier) in order to get rid of it. The dialog is pretty far removed from the table's parent panel. (Panel -> JTable -> CellEditor -> JFormattedTextField -> InputVerifier -> JDialog)
Any ideas on how to force the dialog to be hidden when the table is destroyed? If you need more details, let me know. I'm trying not to get you guys bogged down in the details, but there is a lot going on.
As a first thought, can you not go down the listener approach. If you have a closeErrorDialog() type method that gets called when upon successful valdiation, then you can also call it when a menu action is selected.
As an alternative, perhaps you could control the transition from menu to menu in some way, and create a "cleanup" method which will close down any exisiting error dialogs. This would allow for any other actions that need to take place when changing menus, to happen in the same place.
Just a couple of quick ideas of the top of my head. Hope they are along the lines of what you meant
Many people will vote me down for saying this, but it sounds like your dialog should be modal so that users can't switch away from it without dismissing it first. Or at least disable the menus that allow people to switch away while this dialog is displayed.