I'm trying to understand, whether Platform.runLater() method invokes just the SAME JavaFxApplicationThread, as in start()-method or ANOTHER, PARALLEL thread with the same name?
In the code below:
1) first, start()-method was invoked with JavaFxApplicationThread;
2) then, startFilling()-method was invoked, where new thread starts;
3) at last, new Stage was opened with method openMessage(), where Platform.runLater() method was used.
Please see the code:
public class FillingTimeLine extends Application {
private LongProperty lp = new SimpleLongProperty(0);
private Timeline timeline = new Timeline();
#Override
public void start(Stage primaryStage) throws Exception {
// TODO Auto-generated method stub
System.out.println("\nSTARTING THREAD: " + Thread.currentThread().getName());
StackPane spane = new StackPane();
ProgressBar pb = new ProgressBar(0);
pb.setMinSize(160, 21.5);
pb.setMaxSize(160, 21.5);
pb.setPrefSize(160, 21.5);
pb.progressProperty().bind(lp.divide(10000 * 1.0));
pb.setStyle("-fx-base:darkgray;-fx-accent:red;");
spane.getChildren().add(pb);
Scene scene = new Scene(spane, 300, 300);
primaryStage.setScene(scene);
primaryStage.show();
startFilling();
openNewStage();
}
public void startFilling() throws InterruptedException {
new Thread(() -> {
System.out.println("\nSTARTING THREAD: " + Thread.currentThread().getName());
timeline = new Timeline(new KeyFrame(Duration.seconds(0), new KeyValue(lp, 0)),
new KeyFrame(Duration.seconds(20), new KeyValue(lp, 20000)));
if (Thread.currentThread().isInterrupted()) {
System.out.println("\n THR WAS INTERRUPTED!");
return;
}
timeline.play();
try {
Thread.sleep(20000);
} catch (InterruptedException ex) {
System.out.println("\n THR WAS INTERRUPTED!");
return;
}
}).start();
}
public void stopFilling() {
new Thread(() -> {
System.out.println("\nSTOPPING THREAD: " + Thread.currentThread().getName());
timeline.stop();
}).start();
}
public void openNewStage() {
Platform.runLater(() -> {
System.out.println("\nOPENNING THREAD" + Thread.currentThread().getName());
Stage qst = new Stage();
StackPane sp = new StackPane();
Button btn = new Button("STOP");
btn.setMaxHeight(25);
btn.setMinHeight(25);
btn.setPrefHeight(25);
btn.setMaxWidth(80);
btn.setMinWidth(80);
btn.setPrefWidth(80);
btn.setAlignment(Pos.CENTER);
btn.setOnAction(e -> {
try {
qst.close();
stopFilling();
} catch (Exception e1) {
return;
}
});
sp.getChildren().add(btn);
Scene scene = new Scene(sp, 200, 120);
qst.setX(50);
qst.setY(50);
qst.setScene(scene);
qst.setResizable(false);
qst.show();
});
}
public static void main(String[] args) {
launch(args);
}
}
I thougt Platform.runLater() enables parallel execution. And I expected, that new Stage with a STOP-button would be opened by another thread, because JavaFxApplicationThread was still busy with primaryStage.
But CONSOLE PUTPUT shows that new Stage was opened also with JavaFxApplicationThread- just as primaryStage:
STARTING THREAD: JavaFX Application Thread
STARTING THREAD: Thread-3
OPENNING THREAD: JavaFX Application Thread
STOPPING THREAD: Thread-4
So how can one and the same thread open new Stage, if primaryStage is still showing and is not closed?
Or is OPENING THREAD - another, parallel thread with the same name?
Thank you in advance
Related
I'm trying to update text inside a javafx textArea element instantly to show execution information using both thread and task but nothing seems working, althought when I print something in console it works thus the thread is executing. The program prints all the messages once the program is executed, but i want show the messages as the same time as the program is executing.
Here I have my tsak and thread declarations
#Override
public void initialize(URL url, ResourceBundle rb) {
System.setProperty("webdriver.gecko.driver", "C:\\Users/lyesm/Downloads/geckodriver-v0.26.0-win64/geckodriver.exe");
try {
restoreValues();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
text = new Text(this.getLogs());
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
Runnable updater = new Runnable() {
#Override
public void run() {
printMessages();
System.out.println(" working on ... \n");
}
};
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
}
//Platform.runLater(updater);
}
}
});
thread.setDaemon(true);
thread.start();
service = new Service<Void>() {
#Override
protected Task<Void> createTask() {
return new Task<Void>() {
#Override
protected Void call() throws Exception {
Platform.runLater(() -> textArea.appendText(logs));
return null;
}
};
}
};
service.start();
}
I'm calling the service from this method
public void launchTest() {
this.setLogs("\n\n");
service.restart();
this.setLogs(" Test starting ...\n");
service.restart();
//this.setLogs(" Opening the navigator \n");
this.setDriver(new FirefoxDriver());
//this.setLogs(" Reaching http://127.0.0.1:8080/booksManager ... \n");
driver.get("http://127.0.0.1:8080/booksManager");
//this.setLogs(" Setting test data \n");
driver.findElement(By.id("lyes")).click();
driver.findElement(By.name("email")).sendKeys(pseudo.getText());
driver.findElement(By.name("password")).sendKeys(password.getText());
//this.setLogs(" Submitting ... \n");
driver.findElement(By.name("submit")).click();
if(driver.getCurrentUrl().equals("http://127.0.0.1:8080/booksManager/Views/index.jsp") == true) {
//InputStream input= getClass().getResourceAsStream("https://w0.pngwave.com/png/528/278/check-mark-computer-icons-check-tick-s-free-icon-png-clip-art-thumbnail.png");
//Image image = new Image(input);
//ImageView imageView = new ImageView(image);
Label label = new Label(" Test successed");
testsInfos.getChildren().add(label);
}else {
Text textRes = new Text("\n Test failed ");
textRes.setFill(javafx.scene.paint.Color.RED);
testsInfos.getChildren().add(textRes);
}
driver.close();
}
And here the printMessage method called from the thread
public void printMessages() {
String ll = this.getLogs();
this.text.setText(ll);
testsInfos.getChildren().remove(text);
testsInfos.getChildren().add(text);
textArea.clear();
textArea.setText(ll);
}
Neither method seems to work.
Does anybody have any idea how to fix it ?
Edited:
package application;
import java.util.concurrent.CountDownLatch;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.layout.StackPane;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class Main extends Application {
private Service<Void> service;
#Override
public void start(Stage primaryStage) throws InterruptedException {
StackPane root = new StackPane();
TextArea ta = new TextArea();
ta.setDisable(true);
root.getChildren().add(ta);
Scene scene = new Scene(root, 200, 200);
// longrunning operation runs on different thread
/*Thread thread = new Thread(new Runnable() {
#Override
public void run() {
Runnable updater = new Runnable() {
#Override
public void run() {
incrementCount();
}
};
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
}
// UI update is run on the Application thread
Platform.runLater(updater);
}
}
});
// don't let thread prevent JVM shutdown
thread.setDaemon(true);
thread.start();*/
primaryStage.setScene(scene);
primaryStage.show();
service = new Service<Void>() {
#Override
protected Task<Void> createTask() {
return new Task<Void>() {
#Override
protected Void call() throws Exception {
final CountDownLatch latch = new CountDownLatch(1);
Platform.runLater(new Runnable() {
#Override
public void run() {
try{
ta.appendText("\n Printed ");
}finally{
latch.countDown();
}
}
});
latch.await();
return null;
}
};
}
};
service.start();
showIT();
}
public static void main(String[] args) {
launch(args);
}
public void showIT() throws InterruptedException {
service.restart();
for(int i = 0;i<1000000;i++) {
System.out.println(i);
}
for(int i = 0;i<1000000;i++) {
System.out.println(i);
}
service.restart();
for(int i = 0;i<1000000;i++) {
System.out.println(i);
}
for(int i = 0;i<1000000;i++) {
System.out.println(i);
}
service.restart();
}
}
The two threading rules in JavaFX are:
Long-running code must not be executed on the FX Application Thread, and
Any code that updates the UI must be executed on the FX Application Thread.
The reason for the first rule is that the FX Application Thread is responsible for rendering the UI (among other things). So if you perform a long-running task on that thread, you prevent the UI from being rendered until your task is complete. This is why you only see the updates once everything is finished: you are running your long-running code on the FX Application Thread, preventing it from re-rendering the text area until everything is complete.
Conversely, the code you do run on a background thread (via the Task.call() method) doesn't do anything that takes a long time to run:
#Override
protected Void call() throws Exception {
final CountDownLatch latch = new CountDownLatch(1);
Platform.runLater(new Runnable() {
#Override
public void run() {
try{
ta.appendText("\n Printed ");
}finally{
latch.countDown();
}
}
});
latch.await();
return null;
}
The only thing you do here is schedule an update on the FX Application thread; the call to Platform.runLater() exits immediately. There's no long-running code at all, so no purpose for the background thread on which this runs. (Technically, the call to latch.await() is a blocking call, but it's redundant anyway, since you simply exit the method after waiting.) With this task implementation, there's no difference between calling service.restart();, and ta.appendText("\n Printed");.
So, your showIT() method should be called on a background thread, and can use Platform.runLater() to append text to the text area. Something like:
import java.util.concurrent.CountDownLatch;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.layout.StackPane;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class Main extends Application {
private Service<Void> service;
#Override
public void start(Stage primaryStage) throws InterruptedException {
StackPane root = new StackPane();
TextArea ta = new TextArea();
ta.setDisable(true);
root.getChildren().add(ta);
Scene scene = new Scene(root, 200, 200);
primaryStage.setScene(scene);
primaryStage.show();
// run showIT() on a background thread:
Thread thread = new Thread(this::showIT);
thread.setDaemon(true);
thread.start();
}
public static void main(String[] args) {
launch(args);
}
public void showIT() {
try {
Platform.runLater(() -> ta.appendText("\nPrinted"));
Thread.sleep(1000);
Platform.runLater(() -> ta.appendText("\nPrinted"));
Thread.sleep(1000);
Platform.runLater(() -> ta.appendText("\nPrinted"));
Thread.sleep(1000);
} catch (InterruptedException exc) {
Thread.currentThread().interrupt();
}
}
}
For your original code, I have to make some guesses about which parts of the API you're using are long-running and which aren't. I would start by creating a utility log() method that you can call from any thread:
private void log(String message) {
Runnable update = () -> ta.appendText(message);
// if we're already on the FX application thread, just run the update:
if (Platform.isFxApplicationThread()) {
update.run();
}
// otherwise schedule it on the FX Application Thread:
else {
Platform.runLater(update);
}
}
And now you can do something like:
public void launchTest() {
log("\n\n");
log(" Test starting ...\n");
log(" Opening the navigator \n");
Task<Boolean> task = new Task<>() {
#Override
protected Boolean call() throws Exception {
this.setDriver(new FirefoxDriver());
log(" Reaching http://127.0.0.1:8080/booksManager ... \n");
driver.findElement(By.name("email")).sendKeys(pseudo.getText());
driver.findElement(By.name("password")).sendKeys(password.getText());
driver.get("http://127.0.0.1:8080/booksManager");
log(" Setting test data \n");
driver.findElement(By.id("lyes")).click();
log(" Submitting ... \n");
driver.findElement(By.name("submit")).click();
boolean result = driver.getCurrentUrl().equals("http://127.0.0.1:8080/booksManager/Views/index.jsp");
driver.close();
return result ;
}
};
task.setOnSucceeded(e -> {
if (task.getValue()) {
//InputStream input= getClass().getResourceAsStream("https://w0.pngwave.com/png/528/278/check-mark-computer-icons-check-tick-s-free-icon-png-clip-art-thumbnail.png");
//Image image = new Image(input);
//ImageView imageView = new ImageView(image);
Label label = new Label(" Test successed");
testsInfos.getChildren().add(label);
} else {
Text textRes = new Text("\n Test failed ");
textRes.setFill(javafx.scene.paint.Color.RED);
testsInfos.getChildren().add(textRes);
}
});
Thread thread = new Thread(task);
thread.setDaemon(true);
thread.start();
}
I have the first scene in which I have a registration button on click of the button I try to establish a connection to my server in a background thread. Now I want to go to next scene only when I gets 200 as response code from my server.
I have used Service class for background thread.I have also created a method to change the scene but I am not able to understand where and when to call mehod.
public class MainController implements Initializable {
int responseCodeFromServer;;
// creating background thread
private Service<Void>backgroundThread;
backgroundThread = new Service<Void>()
{
#Override
protected Task<Void> createTask() {
return new Task<Void>() {
#Override
protected Void call() throws Exception
{
// Now here we will try to establish the connection with the Server
EstablishServerConnection obj = new EstablishServerConnection();
responseCodeFromServer = obj.establishConnectionToServer(registrationBeanObj);
System.out.println("Response Code received in UI thread "+ responseCodeFromServer);
if(responseCodeFromServer == 200)
{
updateMessage("All Ok");
// now when we get response code as 200 then we need to take the user to the next window
}
else
{
updateMessage("Server Issue");
}
// TODO Auto-generated method stub
return null;
}
};
}
};
// we will define here what will happen when this background thread completes its job successfully (we can also try for failed or cancelled events)
backgroundThread.setOnSucceeded(new EventHandler<WorkerStateEvent>()
{
#Override
public void handle(WorkerStateEvent event) {
// TODO Auto-generated method stub
if(responseCodeFromServer == 200)
{
System.out.println("Done");
}
// It is a good idea to unbind the label when our background task is finished
status.textProperty().unbind();
}
});
// we need to bind status label text property to the message property in our background thread
status.textProperty().bind(backgroundThread.messageProperty());
// we need to start our background thread
backgroundThread.restart();
}
#Override
public void initialize(URL location, ResourceBundle resources) {
// TODO Auto-generated method stub
System.out.println("Hello World");
}
public void goToProductKey(ActionEvent event) throws IOException
{
Parent goToProductKeyParent = FXMLLoader.load(getClass().getResource("ProductKeyFXML.fxml"));
Scene goToProductKeyScene = new Scene(goToProductKeyParent);
// This line gets the stage Information
Stage window = (Stage)((Node)event.getSource()).getScene().getWindow();
window.setScene(goToProductKeyScene);
window.show();
}
My Question is I want to go to next scene only when i get 200 as response code from my server.I am new to JavaFX
backgroundThread.setOnSucceeded(new EventHandler<WorkerStateEvent>()
{
#Override
public void handle(WorkerStateEvent event)
{
// TODO Auto-generated method stub
if(responseCodeFromServer == 1)
{
Parent goToProductKeyParent = null;
try {
goToProductKeyParent = FXMLLoader.load(getClass().getResource("ProductKeyFXML.fxml"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Scene goToProductKeyScene = new Scene(goToProductKeyParent);
// This line gets the stage Information
Stage window = (Stage) rootPane.getScene().getWindow();
//Stage window = (Stage)((Node)event.getSource()).getScene().getWindow();
window.setScene(goToProductKeyScene);
window.show();
}
// It is a good idea to unbind the label when our background task is finished
status.textProperty().unbind();
}
});
// we need to bind status label text property to the message property in our background thread
status.textProperty().bind(backgroundThread.messageProperty());
// we need to start our background thread
backgroundThread.start();
In a JavaFX application, I have a method which takes a long time on large input. I'm opening a dialog when it is loading and I'd like the user to be able to cancel/close out the dialog and the task will quit. I created a task and added its cancellation in the cancel button handling. But the cancellation doesn't happen, the task doesn't stop executing.
Task<Void> task = new Task<Void>() {
#Override
public Void call() throws Exception {
// calling a function that does heavy calculations in another class
};
task.setOnSucceeded(e -> {
startButton.setDisable(false);
});
}
new Thread(task).start();
cancelButton.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
System.out.println("Button handled");
task.cancel();
}
);
Why isn't the task getting canceled when the button clicked?
You have to check on the cancel state (see Task's Javadoc). Have a look at this MCVE:
public class Example extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
Task<Void> task = new Task<Void>() {
#Override
protected Void call() throws Exception {
new AnotherClass().doHeavyCalculations(this);
return null;
}
};
Button start = new Button("Start");
start.setOnMouseClicked(event -> new Thread(task).start());
Button cancel = new Button("Cancel");
cancel.setOnMouseClicked(event -> task.cancel());
primaryStage.setScene(new Scene(new HBox(start, cancel)));
primaryStage.show();
}
private class AnotherClass {
public void doHeavyCalculations(Task<Void> task) {
while (true) {
if (task.isCancelled()) {
System.out.println("Canceling...");
break;
} else {
System.out.println("Working...");
}
}
}
}
}
Note that…
You should use Task#updateMessage(String) rather than printing to System.out, here it's just for demonstration.
Directly injecting the Task object creates a cyclic dependency. However, you can use a proxy or something else that fits your situation.
I have a TableView associated with some data, and once i hit a run button i perform some processing on that data. Each row of data is handled in a seperate thread, and while those threads are running i want a ProgressInducator to replace the table within its vbox.
In the attached code:
If I stop where is says "WORKS IF STOP HERE" - table is replaced with pi.
If I continue waiting for the threads to join - no replacing.
What am I missing?
runButton.setOnAction(
new EventHandler<ActionEvent>() {
#Override
public void handle(final ActionEvent e) {
List<Thread> threadList = new ArrayList<Thread>();
int threadCounter = 0;
final ProgressIndicator pi = new ProgressIndicator(threadCounter);
vbox.getChildren().clear();
vbox.getChildren().addAll(pi);
for (ProductInTable product : data) {
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try
{
product.calculate();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
});
threadList.add(thread);
thread.start();
}
int x = threadList.size();
/** WORKS IF STOP HERE **/
// wait for all threads to end
for (Thread t : threadList) {
try {
t.join();
threadCounter++;
pi.setProgress(threadCounter / x);
} catch (InterruptedException interE) {
interE.printStackTrace();
}
}
/** DOESNT WORKS IF STOP HERE **/
Thread.join() blocks execution until the thread is completed. Since you are calling this on the FX Application Thread, you block that thread until all your worker threads finish. This means the UI is unable to update until those threads are complete.
A better approach is probably to represent each computation with a task, and update a counter of complete tasks back on the FX Application Thread using setOnSucceeded. Something like:
runButton.setOnAction(
new EventHandler<ActionEvent>() {
#Override
public void handle(final ActionEvent e) {
final ProgressIndicator pi = new ProgressIndicator(threadCounter);
vbox.getChildren().clear();
vbox.getChildren().addAll(pi);
final int numTasks = data.size();
// only access from FX Application thread:
final IntegerProperty completedTaskCount = new SimpleIntegerProperty(0);
pi.progressProperty().bind(completedTaskCount.divide(1.0*numTasks));
completedTaskCount.addListener(new ChangeListener<Number>() {
#Override
public void changed(ObservableValue<? extends Number> obs, Number oldValue, Number newValue) {
if (newValue.intValue() >= numTasks) {
// hide progress indicator and show table..
}
}
});
for (final ProductInTable product : data) {
Task<Void> task = new Task<Void>() {
#Override
public Void call() {
try
{
product.calculate();
} catch (IOException ioe) {
ioe.printStackTrace();
}
return null ;
}
});
task.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
#Override
public void handle(WorkerStateEvent event) {
completedTaskCount.set(completedTaskCount.get()+1);
}
});
new Thread(task).start();
}
}
});
If you potentially have a large number of items here, you should use some kind of ExecutorService instead to avoid creating too many threads:
ExecutorService exec = Executors.newFixedThreadPool(
Runtime.getRuntime().availableProcessors()); // for example...
and then replace
new Thread(task).start();
with
exec.submit(task);
I am working on a basic Java FX task exercise. It counts from 1 to 150 on a thread. The current value is presented on a label and updates a progress bar.
There is a button to start the task, to cancel it and to view canceled status of the task.
The thing that puzzles me is as to why I cannot re run the task after having canceled the thread once(same thing happens if I let the task finnish).
I want to be able to rerun the task . Then I need to make it so that it will resume(though that shouldn't be that hard after figuring out how to rerun the task)
Source ;
public class JavaFX_Task extends Application {
#Override
public void start(Stage primaryStage) {
final Task task;
task = new Task<Void>() {
#Override
protected Void call() throws Exception {
int max = 150;
for (int i = 1; i <= max; i++) {
if (isCancelled()) {
break;
}
updateProgress(i, max);
updateMessage(String.valueOf(i));
Thread.sleep(100);
}
return null;
}
};
ProgressBar progressBar = new ProgressBar();
progressBar.setProgress(0);
progressBar.progressProperty().bind(task.progressProperty());
Label labelCount = new Label();
labelCount.textProperty().bind(task.messageProperty());
final Label labelState = new Label();
Button btnStart = new Button("Start Task");
btnStart.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent t) {
new Thread(task).start();
}
});
Button btnCancel = new Button("Cancel Task");
btnCancel.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent t) {
task.cancel();
}
});
Button btnReadTaskState = new Button("Read Task State");
btnReadTaskState.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent t) {
labelState.setText(task.getState().toString());
}
});
VBox vBox = new VBox();
vBox.setPadding(new Insets(5, 5, 5, 5));
vBox.setSpacing(5);
vBox.getChildren().addAll(
progressBar,
labelCount,
btnStart,
btnCancel,
btnReadTaskState,
labelState);
StackPane root = new StackPane();
root.getChildren().add(vBox);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("java-buddy.blogspot.com");
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
The Task documentation is pretty clear on this.
As with FutureTask, a Task is a one-shot class and cannot be reused. See Service for a reusable Worker.
There is an example of restartable concurrent services in the Service documentation.