Hello? anyone had a problem like: cursor blinking in more than one field at a time?
In my case the following happens: When you double click on a field JTextField, opens a JDialog, so
after closing this, the focus is directed back to the field clicked before opening the screen.
What happens is that after performing this action, two fields are flashing at the same time (usually the first field
screen, as well as the field in which efetuei double click).
This medium is random, there are cases in which it does not occur.
When debugging the inner class Handler, contained within the class DefaultCaret more specifically the actionPerformed method, realized
that: time is a field, and time is another, which are precisely the fields that are flashing (q seems obvious I know). but they are
the own inner classes of Java that are calling the method.
When passing over the field using the Tab, the cursor false, vanishes.
I'm using JDK 6
I returned the focus within the invokeLater(), but not solved. Now both synchronized flash
The first JComponent focusable is one of the fields that flashing improperly
I'm using my own FocusTraversalPolicy, does that may be influencing? The funny thing is that there is no treatment particularly strange about my class.
I noticed that the standard Java class, using a method within the Syncronized getFirstComponent(), but added the same control, but still is not ok
Actually it's Focus issue for me.
Normally when JTextComponent looses Focus setCaretVisible(false) / setSelectionVisible(false) is called and when Focus gained opposite thing happens.
After closing JDialog try to return Focus inside invokeLater(). Also check what's the first focusable JComponent in the JDialog's parent.
This situation occurs because the project I'm developing is quite large, so do not get small examples of implementation
The project has many components, Tables and Container's, which require focus through at the same time.
It turns out that Swing, put in a queue for execution, a lot of threads, and then dispatching them going, and while he did not finish running it, you can cram grabFocus() or requestFocus(), which does not cry, the first he has to finish everything and then run my request focus.
Resolved palliatively this situation, using the Swing SwingUtilities.invokeLater(...);
Thanks for the tips.
Related
I know there are many questions on how to focus on a certain text field and so on, but it seems that the issue I am facing is a bit different. So, I have a JTextField which has functionality to autocomplete the text if something that is currently in it has been typed before by the user. I also have a set of buttons that perform insertion of some predefined portion of text into the text field when pressed. The problem is that every time any new text appears in the text field, the autocomplete can trigger and append the text that was used by the user previously. In order to it more friendly, I decided to select the part appended by the autocomplete. All the code is executed in the ED thread. Consider the case when the text field was not in focus :
Both code samples are in the actionPerformed method of the button.
// does not work
if (textField.requestFocusInWindow()) {
textField.getDocument().insertString(...);
}
The insertString() is overriden and has all the logic to select appended string by the autocomplete. So, the only thing I need is that the text field is selected before the string is inserted.
I tried :
// does work
textField.requestFocusInWindow();
SwingUtilities.invokeLater(() -> {
textField.getDocument().insertString(...);
});
The official doc says :
The call to the requestFocusInWindow method initiates the focus transfer, but it does not immediately move the focus ...
This sort of makes sense, since to acquire the focus, a call must be made to the window manager of the clients operating system (that's how I understand that, correct me if I am wrong).
Is the second example working mainly because both events (getting focus and inserting the string) are added to the event queue and the insertion appears after the focus request (actually at the end of the queue) or am I missing something? Is it a valid solution? Can it be done better?
Note: simply adding a listener to the text field ( to react when it is in focus) is not a solution, since the logic I described here is only a part of the whole functionality used.
I've read through lots of the threads on paintComponent here, most of which making the point that it either is never or almost never necessary (or possible) to choose when paintComponent is called.
In my program, however, sometimes (only sometimes) paintComponent gets called before some of the objects it needs to paint have finished initializing or even sometimes before they've been created, triggering warnings- JOptionPane pop-ups, which surprisingly do not show any of the text they were hard-coded to display in their "message" area. I've read in other places that it's something to do with the EDT, and I've looked into some parts of that but I'm just getting confused. If the main purpose of the EDT is to update the gui, and by default pretty much everything will run in the EDT, then could I tell the program to run all the initialization and update functions in a different thread(s), which I somehow forcibly make run before the EDT runs?
What I'd ideally like to have happen is for paintComponent to wait until a certain point in my code to be run (after a bunch of update functions, regardless of what happens to the screen. After it does get called, it is followed by a pause in which relatively little is going on ( I had been using Thread.sleep() inside a while loop ) and which lasts until the user clicks something - at which point all the necessary functions are run again, followed by paintComponent afterwards, then the sleep() while loop, etc.
From what I understand, I think what I want isn't really possible, so my question is: Do you guys have any ideas of how to get around this?
EDIT:
So essentially the program is a college course planner, intended to make it easier for someone to plan out by semester all the courses they have to take before graduation, move those courses around (if possible), and see how all the courses are connected (prerequisites and such). When the program starts, it loads the list of necessary courses from a text file, then loads info about each course from a bunch of individual text files, and arranges them according to their prerequisites. Courses with no prerequisites go in the first semester, courses whose prerequisites have all been added to the first semester get added to the second, and so on until all the courses have been added. When paintComponent runs, it calls a function that assume all of each course's prerequisites exist on the schedule, and if it finds otherwise, it throws an error and displays a JOptionPane message box. When this happens during a normal run of the program (like if I manually add a course before adding its prerequisites), that all works and displays correctly. But sometimes that message box pops up when only some of the courses have been loaded (meaning control is still in the main constructor) and when it does so, the actual string message doesn't show up - only the actual pane, title and ok button do. Heres the line where I display the error box, so you can know that I'm not trying to display a string variable which has the potential of being empty.
JOptionPane.showMessageDialog(this,
"Course couldn't be loaded, partially >loaded\ncourses have been removed.",
"Error",
JOptionPane.OK_OPTION);
It is the "Course couldn't...been removed." part that doesn't get displayed. This is the only JOptionPane I display with the title "Error".
This post mentioned what sounds like the same thing happening, except I'm not using any of the things that poster had to fix. So possibly it's irrelevant but I'll add it just in case. JOptionPane.showMessageDialog() shows but without any message?
But to step back a bit, because that box popped up before all the courses had been added, it means that paintComponent was somehow called in the middle of the relevant JPanel's constructor, before a bunch of things had been initialized. I added a bunch of println() statements to make sure that that is true. Is it normal for that to happen, and if so, is there a way to fix it without simply using Andrew Thompson's advice?
After thinking though it a bit, I think that because the project is 3200 lines long and relies to a huge extent on text files, I'm really not sure how to ( or if I can) make a SSCCE for it..
If any specific pieces would be helpful I'll gladly add those but if this problem isn't clearly some standard issue I'm getting wrong, then I'll just add that flag and keep looking for bugs.
Thanks for your help
Declare a flag as a class attribute. Check it in the paint method. Change it at the end of the initialization.
class XandYandZ extends JComponent {
boolean initializationFinished = false;
public XandYandZ() {
// long initialisation..
initializationFinished = true;
}
public void paintComponent(Graphics g) {
if (!initializationFinished) return;
// .. paint ..
Note: see the edit (save some time reading)
I'm trying to make my mind-mapping program respond to shortcuts like CTRL+RIGHT (reordering nodes) and TAB (insert child at next indent level). I have a JPanel that handles all of the keystrokes. It resides inside of a JTabbedPane that might be the cause for Key Bindings not working. I've chickened out and decided to just use KeyListener.
The problem is that with the aforementioned key combinations, Swing automatically shifts the focus to some other component. I'd rather not manually put setFocusable(false) everywhere. How can I disable these shortcuts altogether in such a way that the focus will not be shifted, and the relevant KeyEvents will still be sent to my JPanel?
Edit:
I used the following code:
for (int id : new int[] {KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS})
setFocusTraversalKeys(id, Collections.EMPTY_SET);
to disable the default traversal keys (particularly TAB.)
Now the issue is actually why CTRL+UP causes a loss of focus. When pressing CTRL+DOWN, for instance, it's fine. The component behaves as expected. But with CTRL+UP, it works as expected and then focus is shifted/lost somehow. Can anyone say what CTRL+UP means and how to disable it wherever it is? Google isn't helping.
KeyBinding are used for all KeyEvents implemented in Swing APIs, maybe there is/are conflict
is required to override required KeyBindings, change used Keys, set to null, e.i. depends of your requirements
list of KeyBindings by #camickr
I have 5 JFrames in my application and I want the values from all 5 JFrames to be sent to a single JFrame. And it is a process where I have to go one frame to another and the value entered previously should not be lost and must be visible at the end of the process.
Easy example is,
I key in my name in the first frame,
then I key in my Address in the second frame,
then my mobile number in the third frame
and so on till the last frame where I want my keyed in details in the previous forms to be in the final frame to display my data in JTextfields. Is this possible? Because if it is a single form, I know how to do it. But when it is multiple forms in this situation I am lost. Please help.
This has nothing to do with Swing or JFrames and all to do with the general issue of getting information from one object into another. Yes it's possible -- give the classes that you wish to extract information from "getter" methods, and then call them when you want the information. If you want to gather this information in an event-dependent fashion, then you will need to have one class listening for state changes brought on by events in the other classes. A PropertyChangeListener can work well for this.
Or if you use modal JDialog windows instead of JFrames, you will always be notified when the dialog has returned and is no longer visible, since the calling code's program flow resumes from right after where it told the dialog to become visible.
Next we can discuss whether having 5 separate JFrames is a good idea or not. I'm guessing you know my opinion on this, else I wouldn't have mentioned the subject.
I have a simple program that utilizes Java Swing Timer to display an image for 400 miliseconds, in this period of time I just want to stop all ActionListeners or stop taking ActionEvents. I've got 40+ buttons and want a simple way to do this.
Is there anyway to do that in Java?
Can you determine that you are in this "image displayed" state? The image goes up and you set the state to "image displayed" or whatever. Go through your widgets and decide which ones are supposed to be dead while the image is up. Turn them into Observers of this state value. When the state changes, they either enable or disable, as appropriate. The image code doesn't do anything directly to any widget. It just declares that the state is now "image displayed". It's up to the Observers to decide what to do, if anything, with that information.
Or use the GlassPane. That works too. Of course, the GlassPane shuts down everything. If you need to be more selective, you need a more fine-tuned approach.
You can use a temporary GlassPane instance to consume all events by registering empty listeners to it.
Use an undecorated modal JDialog to display the image. Before you make the dialog visible you would start a Timer. When the Timer fires in 400 ms you close the dialog.
I've had similar issues and typically found that its a design issue that got me in that situation. Being the case, I still had to find away around it. To fix the issue, I kept a list of the elements that I wanted to disable (stop listening) and iterated through them at the beginning and end of the timer. For buttons it should be as simple as:
for(Component c : listOfToggledComponents){
c.setEnabled(shouldItBeEnabled);
}
For buttons, this will grey out the button. Similar things happen to other swing components.