Everyone who is doing programming inward coffee swing has to come upward across invokeAndWait in addition to invokeLater provided past times SwingUtilites. In this coffee swing tutorial nosotros volition larn almost both invokeLater() in addition to invokeAndwait() method. In showtime business office nosotros volition generally focus on invokeLater in addition to volition honor answers to questions similar What is invokeLater, how to role invokelater inward coffee swing, instance of invokelater inward swing etc spell inward instant business office of this invokeLater tutorial nosotros volition larn to a greater extent than almost invokeAndWait method inward coffee swing in addition to volition larn Why nosotros demand InvokeAndWait, how to role InvokeAndWait method inward coffee Swing in addition to differences betwixt invokelater in addition to invokeAndWait.
Finally, nosotros volition run across a code instance of both invokeLater in addition to invokeAndWait inward Swing in addition to volition survive able to create upward one's heed when to role invokeLater in addition to when to role invokeAndWait spell doing Swing programming. We volition every bit good run across famous Swing interview questions "difference betwixt invokeLater in addition to invokeAndWait" at the destination of the article.
Why create nosotros demand InvokeLater method inward Swing?
Before using invokelater or going deep almost invokelater lets run across why create nosotros demand this method inward swing utility class? As nosotros all know coffee swing is non threadsafe , you lot tin non update swing element similar JButton, JLable , JTable or JTree from whatever thread , they all needs to survive updated from precisely i thread in addition to nosotros telephone band it Event Dispatcher thread or EDT inward short. Event Dispatcher thread is used to homecoming graphics for coffee swing element in addition to every bit good procedure all events corresponding to a fundamental press, mouse click or whatever action. So if you lot desire to update a item swing element suppose label of a JButton from Yes to No you lot demand to create this inward Event Dispatcher thread in addition to for doing this you lot demand InvokeLater. invokeLater is used to perform whatever chore asynchronously on AWT Event Dispatcher thread.What is invokeLater inward Java Swing
The invokeLater() is a method inward coffee on swing parcel in addition to belongs to SwingUtilities class. Invokelater is used past times coffee swing developer to update or perform whatever chore on Event dispatcher thread asynchronously.invokeLater has been added into Java API from swing extension in addition to it belongs to SwingUtilities class.
How does invokeLater industrial plant inward Java Swing
If you lot run across the signature of invokeLater method you lot volition honor that invokeLater takes a Runnable object in addition to queues it to survive processed past times EventDispatcher thread. EDT thread volition procedure this asking entirely after sorting out all AWT pending events or requests. Even if invokeLater is called straight cast Event dispatches thread processing of Runnable chore withal survive done entirely after processing all pending AWT Events. An of import betoken to Federal Reserve annotation is that inward instance if the run method of Runnable chore throws whatever exception in addition to then AWT Event dispatcher thread volition unwind in addition to non the electrical flow thread.
Why create nosotros demand InvokeAndWait method inward Swing
As nosotros know that Swing is non thread-safe in addition to we tin non update the Swing element or GUI from whatever thread. If you lot endeavour to update GUI cast whatever thread you lot volition acquire unexpected number or exception, it could survive your GUI mightiness non survive visible or only disappeared. The entirely method which is thread-safe inward the swing is repaint() in addition to revalidate(). On the other hand, InvokeAndWait allows us to update the GUI from EDT thread synchronously. InvokeAndWait method every bit good belongs to swingUtility bird similar invokeLater.
How does InvokeAndWait industrial plant inward Java Swing
If you lot expression at the signature of invokeAndWait method you lot volition run across that it takes a Runnable object in addition to run method of that Runnable is executed synchronously on EDT. This is a blocking telephone band in addition to hold off until all pending AWT events acquire processed and run() method completes. Its a preferred means of updating GUI cast application thread.
An of import betoken to Federal Reserve annotation is that it should non survive called from EventDispatcher thread dissimilar invokeLater; it’s an mistake because it volition number inward guaranteed deadlock. because if you lot cal invokeAndWait from EDT thread it volition survive an AWT lawsuit in addition to caller of invokeAndWait volition hold off for EDT thread to consummate in addition to EDT volition hold off for caller thread to survive completed hence they volition survive locked inward deadlock. Its every bit good of import to holler upward that if run() method of Runnable object throw an exception in addition to then its caught inward AWT EDT thread in addition to rethrown every bit InvocationTargetException on caller thread.
Example of InvokeLater inward Java Swing
Here is an instance of invokeLater() inward Swing which volition demonstrate that inward the instance of invokeLater application thread doesn’t block.
Runnable pickHighBetaStock = new Runnable() {
public void run() {
System.out.println("High beta Stock picked by " + Thread.currentThread());
}
};
SwingUtilities.invokeLater(pickHighBetaStock);
System.out.println("This mightiness good survive displayed earlier the other message. if Event-dispatcher thread is busy");
Example of using InvokeAndWait inward Java Swing
In this instance of InvokeAndWait, nosotros volition run across that Application thread volition block until Runnable object passed to EDT has been executed.
final Runnable pennyStockPicker = new Runnable() {
public void run() {
System.out.println("pick penny Stock on " + Thread.currentThread());
}
};
Thread stockPicker = new Thread() {
public void run() {
try {
SwingUtilities.invokeAndWait(pennyStockPicker);
}
catch (Exception e) {
e.printStackTrace();
}
System.out.println("This volition destination after pennyStockPicker thread because InvokeAndWait is block call" + Thread.currentThread());
}
};
stockPicker.start();
Difference on InvokeLater vs InvokeAndWait inward Swing
Swingutilies provides us ii methods for performing whatever chore inward Event dispatcher thread. Now let's run across what the divergence betwixt invokeLater in addition to InvokeAndWait is in addition to when to role invokeLater.
1) InvokeLater is used to perform a chore asynchronously inward AWT Event dispatcher thread while InvokeAndWait is used to perform chore synchronously.
2) InvokeLater is non-blocking telephone band spell InvokeAndWait volition block until the chore is completed.
3) If the run method of Runnable target throws an Exception in addition to then in the instance of invokeLater EDT threads unwinds spell inward the instance of the invokeAndWait exception is caught and rethrown every bit InvocationTargetException.
4) InvokeLater tin survive safely called from Event Dispatcher thread spell if you lot telephone band invokeAndWait from EDT thread you lot volition acquire an mistake because every bit per coffee documentation of invokeAndWait it clearly says that "this asking volition survive processed entirely after all pending events" in addition to if you lot telephone band this from EDT this volition conk i of pending lawsuit hence its a deadlock because caller of InvokeAndWait is waiting for completion of invokeAndWait spell EDT is waiting for caller of InvokeAndWait.
5) InvokeLater is to a greater extent than flexible inward price of user interaction because it precisely adds the chore inward queue in addition to allow the user to interact amongst the organization spell invokeAndWait is a preffered means to update the GUI from application thread.
In Summary, nosotros tin precisely state that since Swing is non thread-safe in addition to nosotros cannot update different Swing GUI components on whatever thread other-than Event dispatcher Thread nosotros demand to role InvokeAndWait or InvokeLater to schedule whatever Runnable chore for AWT Event dispatcher Thread. InvokeAndWait is synchronous in addition to blocking telephone band in addition to hold off until submitted Runnable completes spell InvokeLater is asynchronous in addition to non-blocking it volition precisely submit chore in addition to exit."
That’s all on InvokeAndWait() in addition to InvokeLater() method of SwingUtilities class. They are really of import spell doing GUI programming on Swing every bit good every bit this is really pop interview questions which I conduct keep discussed inward my latest post service on swing interview questions asked inward Investment banks.
Please allow me know your sense amongst InvokeLater() in addition to InvokeAndWait() method in addition to whatever number you lot institute spell using them which would worth survive mentioning here.
Further Reading
Java Swing (GUI) Programming: From Beginner to Expert
How to override equals method inward Java
What is Abstraction inward coffee ?
How to convert String to int inward Java