When I click on a button in Silverlight I want to run a method 2 seconds later once only for each time I click the button .. in the meantime the rest of the app keeps working .. obviously Thread.Sleep stops the whole UI .. how do I do this?
Inside handler start a new thread that will wait 2 seconds and execute your method. I mean something like
public void button_click(...)
{
(new Thread( (new ThreadWorker).DoWork).Start();
}
public class ThreadWorker
{
public void DoWork() { Thread.Sleep(2); RunMyCustomMethod();}
}
Related
I have a problem with a button in that it doesn't work on the first click. I have to click twice and it then gives double results:
Button button = new Button("Click Me");
button.addClickListener(
new Button.ClickListener() {
public void buttonClick(ClickEvent event) {
new Thread(new Runnable() {
#Override
public void run() {
DateChooser dateChooser = new DateChooser(new com.kopiright.xkopi.lib.type.Date(2013, 12, 9));
System.out.println(dateChooser.selectDate(com.kopiright.xkopi.lib.type.Date.now()).toString());
}
}).start();
}
}
);
DateChooser extends com.vaadin.ui.Panel class.
Vaadin Button is always immediate so that's not the problem here.
The problem is that you are starting an external thread, which updates the UI, and to see changes made to the UI by an external thread, you should use pollig or pushing. In this case the second button click polls the changes to the browser. But in this case you can just remove the thread:
button.addClickListener(new Button.ClickListener() {
public void buttonClick(ClickEvent event) {
DateChooser dateChooser = new DateChooser(new com.kopiright.xkopi.lib.type.Date(2013, 12, 9));
System.out.println(dateChooser.selectDate(com.kopiright.xkopi.lib.type.Date.now()).toString());
}
});
And when an external thread is used to update Vaadin components, the code must be synchronized correctly.
Is there a reason you create a new thread for this?
Please be aware that modifying the GUI from a thread mus be synchronized.
Look in the book of vaadin for this:
11.16.3. Accessing UI from Another Thread
https://vaadin.com/de/book/vaadin7/-/page/advanced.push.html
André
I want to as if there is any way to execute a function after a specific time in windows phone 7.? For instance, see this code in android:
mRunnable=new Runnable()
{
#Override
public void run()
{
// some work done
}
now another function
public void otherfunction()
{
mHandler.postDelayed(mRunnable,15*1000);
}
Now the work done in upper code will be executed after 15 seconds of execution of otherfunction().
And I want to know is this possible in any way in windows phone 7 also.?
Thanx to all in advance..
Although you can use the Reactive Extensions if you want, there's really no need. You can do this with a Timer:
// at class scope
private System.Threading.Timer myTimer = null;
void SomeMethod()
{
// Creates a one-shot timer that will fire after 15 seconds.
// The last parameter (-1 milliseconds) means that the timer won't fire again.
// The Run method will be executed when the timer fires.
myTimer = new Timer(() =>
{
Run();
}, null, TimeSpan.FromSeconds(15), TimeSpan.FromMilliseconds(-1));
}
Note that the Run method is executed on a thread pool thread. If you need to modify the UI, you'll have to use the Dispatcher.
This method is preferred over creating a thread that does nothing but wait. A timer uses very few system resources. Only when the timer fires is a thread created. A sleeping thread, on the other hand, takes up considerably more system resources.
You can do that by using threads:
var thread = new Thread(() =>
{
Thread.Sleep(15 * 1000);
Run();
});
thread.Start();
This way, the Run method wil be executed 15 seconds later.
No need for creating threads. This can be done much more easier using Reactive Extensions (reference Microsoft.Phone.Reactive):
Observable.Timer(TimeSpan.FromSeconds(15)).Subscribe(_=>{
//code to be executed after two seconds
});
Beware that the code will not be executed on the UI thread so you may need to use the Dispatcher.
I am trying to write a code that will make things appear on the screen at predetermined but irregular intervals using javafx. I tried to use a timer (java.util, not javax.swing) but it turns out you can't change anything in the application if you are working from a separate thread.(Like a Timer) Can anyone tell me how I could get a Timer to interact with the application if they are both separate threads?
You don't need java.util.Timer or java.util.concurrent.ScheduledExecutorService to schedule future actions on the JavaFX application thread. You can use JavaFX Timeline as a timer:
new Timeline(new KeyFrame(
Duration.millis(2500),
ae -> doSomething()))
.play();
Alternatively, you can use a convenience method from ReactFX:
FxTimer.runLater(
Duration.ofMillis(2500),
() -> doSomething());
Note that you don't need to wrap the action in Platform.runLater, because it is already executed on the JavaFX application thread.
berry120 answer works with java.util.Timer too so you can do
Timer timer = new java.util.Timer();
timer.schedule(new TimerTask() {
public void run() {
Platform.runLater(new Runnable() {
public void run() {
label.update();
javafxcomponent.doSomething();
}
});
}
}, delay, period);
I used this and it works perfectly
If you touch any JavaFX component you must do so from the Platform thread (which is essentially the event dispatch thread for JavaFX.) You do this easily by calling Platform.runLater(). So, for instance, it's perfectly safe to do this:
new Thread() {
public void run() {
//Do some stuff in another thread
Platform.runLater(new Runnable() {
public void run() {
label.update();
javafxcomponent.doSomething();
}
});
}
}.start();
Questions about threads are in no shortage, I know, but I can't seem to find a "full" example of a thread doing http work and then coming back to update the UI.
I basically call a few web services upon app launch. I obviously don't want to freeze the UI so I would want to use a separate thread, right? I have found a bunch of examples online on how to get a new thread to perform some task. But I haven't yet found one that shows how to actually update the UI when the thread's task is done.
How do I know when the web service thread is done? Is there a callback method? Can I access the UI from this callback method if one exists.
Edit: (Here is some code)
//The activate method is called whenever my application gains focus.
public void activate(){
DoSomething wsThread = new DoSomething();
wsThread.start();
}
public void wsCallBack()
{
myTabScreen.add(new ButtonField("Callback called"));
}
public class DoSomething extends Thread
{
public void run()
{
try
{
wsCallBack();
}
catch(Exception e)
{
}
}
}
Very simple. But it never creates the button.
Any ideas?
Thanks a lot.
You can set up a "callback" system to notify the UI when the threads complete. Have a class that extends Thread and pass to it a reference of the class that should be called at the end. If you have a list of such classes that needs to be notified create a Vector on the Thread implementation to hold them. Override the run function and after doing everything you need to do simply call a method on the UI class (iterating through the vector if needed). So your classes may look like:
public class commThread extends Thread{
MyUIClass callbackObj;
public commThread(MyUIClass myUiClass){
callbackObj = myUiClass;
}
public void run(){
//do stuff
callbackObj.callback();
}
}
and your UI class:
public MyUIClass{
public void callback(){
//refresh the UI
}
}
Of course if you have multiple threads running at the same time and calling the same UI object make sure to synchronize the callback method.
Hope this helps!
As my user changes the CurrentItem of a dataForm, I need to go the server to get addtional data. It's quite likely that the user could scroll through several items before finding the desired one. I would like to sleep for 500ms before going to get the data.
Is there a component already in the SDK or toolkit like a background worker that would assist in getting back to the UI thread to make my WCF async call once the 500ms sleep is done? It seems that if I don't do that, and try instead to call the WCF async method on the sleeper thread then the Completed event fires on the sleeper thread and not the UI thread, which of course is not good.
I think you might be a little off-track in your thinking. I'm not sure why you feel you need to get back to the UI thread in order to make the asych call. Generally you do as much work as you can on a BG thread and only marshal back to the UI thread when you have the results (by way of the Dispatcher).
I typically use a System.Threading.Timer for this purpose:
public class MyViewModel
{
private readonly Timer refreshTimer;
public MyViewModel()
{
this.refreshTimer = new Timer(this.DoRefresh);
}
public object CurrentItem
{
get { ... }
set
{
...
Invalidate();
}
}
// anything that should invalidate the data should wind up calling this, such as when the user selects a different item
private void Invalidate()
{
// 1 second delay
this.refreshTimer.Change(1000, Timeout.Infinite);
}
private void DoRefresh()
{
// make the async call here, with a callback of DoRefreshComplete
}
private void DoRefreshComplete()
{
// update the UI here by way of the Dispatcher
}
}