I have the first JFrame and it works fine. When I push a button it is supposed to show a JProgressBar frame , but i get empty JFrame. I open it with
p = new Progress("1/3");
p.setMax(2);
p.setProgress(0, "Getting bytes...");
Anyone know why?
EDIT:
I am going to explain more detail(Because someone misunderstood and corrected my post in the wrong way) - On my main class i start the first JFrame:
new Crypt();
And in the Crypt class i have registered a button ActionListener. OnClick it opens a second JFrame But it is empty:
p = new Progress("1/3");
p.setMax(2);
p.setProgress(0, "Getting bytes...");
The Progress class
Screen shot
in the Crypt class i have registered a button ActionListener. OnClick it opens a second JFrame But it is empty
Code invoked from an Swing listener executes on the Event Dispatch Thread (EDT). The EDT is responsible for painting Swing components. Since your code is executing a long running task on the EDT y9ou are preventing Swing from painting the component until the task is finished.
You need to start a separate Thread for your long running task. Or better yet you should probably be using a SwingWorker. Read the section from the Swing tutorial on Concurrency in Swing which explains this in more detail and provides a working example of a SwingWorker.
Related
I have a question. I couldn't solve it for 4 days. I'm making a stopwatch using gui swing in Java. There are 1 jframe and 1 jdialog. I used threads in Jframe. It has a start stop and reset button, it works very well. The problem is; I had to use the jdialog like this (this is the job situation) so when I press the start stop and reset button that I created in jdialog, it triggers the start, stop and reset button in the jframe. There is no problem with triggering either. The main problem is this: While the thread works as it should in the jframe, it does not work when I call it from jdialog. I searched a lot, I made a logic, but I couldn't find it, can anyone help?
In a JFrame, when I click on 'login', I pop up another Jframe which is the login window.
How do I make my main Jframe wait for my login Jframe to exit, before doing anything else?
Just use a modal dialog in stead of a frame, that way you cannot do anything else until it'is closed
see http://mindprod.com/jgloss/modal.html for explanation
and see http://www.java2s.com/Tutorial/Java/0240__Swing/ASimpleModalDialog.htm for code example
If you insist on using a JFrame, you could use a workaround by cover the other frame by a glassframe.. Not too a nice solution, I admit..
I agree that a modal dialog would be the best option here, but if I were to answer this question in it's more general form, say:
How do I make one JFrame wait for another JFrame?
I would say the easiest way to acheive this is by registering and firing event listeners.
In your "child" frame, register the "main" frame as an event listener.
In your "main" frame,
implement your choice of listener, e.g. ActionListener
in the method called by the listener, e.g. actionPerformed, code the logic that handles what happens upon each of the actions it can respond to in the "child" frame.
One can easily implement this to a ny number of situations, including the login scenario described in the question.
Use JModalFrame instead of JFrame.
(In my applicaton with Swing GUI) I want to display GlassPane during some work performed in a loop or method, which is called after clicking JButton.
For example:
(action performed after clicking a button)
if (item.equals(button)) {
glassPane.setVisible(true);
someTimeConsumingMethod();
glassPane.setVisible(false);
}
Running this code results in not showing the glassPane during execution of someTimeConsumingMethod() - GUI just freezes for a moment, before result is displayed. Removing last line in that loop (glassPane.setVisible(false);) results in showing glassPane after the method is done (when GUI unfreezes).
Is there a simple way to show that glassPane before GUI freezes, or I need to use some advanced knowledge here? (threads?)
UPDATE1:
I've updated my code according to davidXYZ answer (with two changes):
(action performed after clicking a button)
if (item.equals(button)) {
glassPane.setVisible(true);
new Thread(new Runnable(){
public void run(){
someTimeConsumingMethod(); // 1st change: running the someTimeConsumingMethod in new Thread
// instead of setting glassPane to visible
}
}).start();
// 2nd change: moved glassPane.setVisible(false); inside the someTimeConsumingMethod(); (placed at the end of it).
}
The point of 1st change is that setting glassPane visible in new thread right before running someTimeConsumingMethod in my GUI thread was revealing the glassPane after someTimeConsumingMethod finished (double-checked this).
Now it works fine, thank you for all answers. I will definitely check all the links you provided to actually understand threads!
UPDATE2:
Some more info: someTimeConsumingMethod(); in my application is prepering new Swing Components accoriding to the XML data (cards builded from JButtons and JLabels with few JPanels where needed, and adding them in correct places).
UPDATE3:
I am trying to make it work using SwingWorker's invokeLater method. Now it looks like that:
(action performed after clicking a button)
if (item.equals(button)) {
glassPane.setVisible(true);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
someTimeConsumingMethod();
glassPane.setVisible(false);
}
});
}
It works not that good as code from UPDATE1 (but still - it works). Problems are:
glassPane loads without .gif animation (file is setted up in custom glassPane class - it works with UPDATE1 code)
there is small delay at the end of "working" process - first cursor changes to normal (from the WAIT_CURSOR), and after very short moment glassPane disappear.
Cursor is changed by the custom glassPane class on activation/deactivation (no delay using new Thread way).
Is it correct way of using SwingWorker's invokeLater method?
EDIT: My mistake, I confused SwingWorker with SwingUtilities.invokeLater(). I guess the image issue is due to GUI freezing when the someTimeCOnsumingMethod starts.
GUI just freezes for a moment, before result is displayed. Removing last line in that loop (glassPane.setVisible(false);) results in showing glassPane after the method is done (when GUI unfreezes).
this is common issue about Event Dispath Thread, when all events in EDT are flushed to the Swing GUI in one moment, then everything in the method if (item.equals(button)) { could be done on one moment,
but your description talking you have got issue with Concurency in Swing, some of code blocking EDT, this is small delay, for example Thread.sleep(int) can caused this issue, don't do that, or redirect code block to the Backgroung taks
Is there a simple way to show that glassPane before GUI freezes, or I need to use some advanced knowledge here? (threads?)
this question is booking example why SwingWorker is there, or easier way is Runnable#Thread
methods implemented in SwingWorker quite guarante that output will be done on EDT
any output from Runnable#Thread to the Swing GUI should be wrapped in invokeLater()
easiest steps from Jbuttons Action could be
show GlassPane
start background task from SwingWorker (be sure that listening by PropertyChangeListener) or invoke Runnable#Thread
in this moment ActionListener executions is done rest of code is redirected to the Backgroung taks
if task ended, then to hide GlassPane
create simple void by wrapping setVisible into invokeLater() for Runnable#Thread
in the case that you use SwingWorker then you can to hide the GlassPane on proper event from PropertyChangeListener or you can to use any (separate) void for hidding the GlassPane
best code for GlassPane by #camickr, or my question about based on this code
You are blocking the EDT (Event Dispatching Thread, the single thread where all UI events are handled) with your time consuming job.
2 solutions:
Wrap the calls to:someTimeConsumingMethod();glassPane.setVisible(false); in SwingUtilities.invokeLater(), this will allow the frame to repaint itself once more. However this will still freeze your GUI.
Move your someTimeConsumingMethod() into a SwingWorker (this is the recommended option). This will prevent your GUI from ever freezing.
Read the javadoc of SwingWorker to understand better what is going on and how to use it.
You may also learn a lot in this tutorial about Swing and multi-threading
JButton startB = new JButton("Start the big operation!");
startB.addActionListener(new ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent A) {
// manually control the 1.2/1.3 bug work-around
glass.setNeedToRedispatch(false);
glass.setVisible(true);
startTimer();
}
});
glasspane here used here is FixedGlassPane glass;
ref: http://www.java2s.com/Code/Java/Swing-JFC/Showhowaglasspanecanbeusedtoblockmouseandkeyevents.htm
Guillaume is right. When you are on the main thread, each line will finish before the next line. You definitely need another thread.
An easy way to solve your problem is to spin off the display of the glasspane in another thread (normal thread or Swing threads - either will work fine).
if (item.equals(button)) {
new Thread(new Runnable(){
public void run(){
glassPane.setVisible(true);
}
}).start();
someTimeConsumingMethod();
glassPane.setVisible(false);
}
That way, a different thread is blocked by setvisible(true) while someTimeConsumingMethod() runs on the main thread. When it's done, glasspane will disappear. The anonymous thread reaches the end of the run method and stops.
Okay, so I've got my menu system up and working from a JFrame. Everything seems to work really well, up until I click the button which starts a canvas. Now what the canvas does is intialize a JFrame which extends Canvas so I can't use a thread. Once the frame is up and running it calls a method which has a while true {} after this I am unable to close the frame. This has never been an issue before when running the canvas application using static void main. How can I fix this issue of the new JFrame not closing?
How can I fix this issue of the new JFrame not closing?
Don't block the EDT (Event Dispatch Thread) - the GUI will 'freeze' when that happens. Instead of creating an infinite loop, implement a SwingWorker for long running tasks. See Concurrency in Swing for more details.
1. Make this a rule of thumb when working with GUI application, that Always keep the UI work on the UI thread and Non-UI work on the Non-UI thread.
2. Second doNot mix up SWING AND AWT.
3. The main() method in Java Gui is not long lived, after scheduling the work in the Event Dispatcher Thread (EDT) the main() method quits. Now its solely the responsibility of the EDT to handle the GUI.
4. So never mixup the Non-UI process-intensive work, with the EDT.
Use EDT to handle the GUI.
Eg:
public static void main(String[] args){
EventQueue.invokeLater(new Runnable(){
myframe.setVisible(true);
});
}
In a JFrame, when I click on 'login', I pop up another Jframe which is the login window.
How do I make my main Jframe wait for my login Jframe to exit, before doing anything else?
Just use a modal dialog in stead of a frame, that way you cannot do anything else until it'is closed
see http://mindprod.com/jgloss/modal.html for explanation
and see http://www.java2s.com/Tutorial/Java/0240__Swing/ASimpleModalDialog.htm for code example
If you insist on using a JFrame, you could use a workaround by cover the other frame by a glassframe.. Not too a nice solution, I admit..
I agree that a modal dialog would be the best option here, but if I were to answer this question in it's more general form, say:
How do I make one JFrame wait for another JFrame?
I would say the easiest way to acheive this is by registering and firing event listeners.
In your "child" frame, register the "main" frame as an event listener.
In your "main" frame,
implement your choice of listener, e.g. ActionListener
in the method called by the listener, e.g. actionPerformed, code the logic that handles what happens upon each of the actions it can respond to in the "child" frame.
One can easily implement this to a ny number of situations, including the login scenario described in the question.
Use JModalFrame instead of JFrame.