The WebEngine.getLoadWorker() method returns a Worker object that tracks the progress of the page loading.

The most important properties of Worker are the following:

• progressProperty: This represents the page loading progress
• stateProperty: This represents the status of the loading process, especially Worker.State.FAILED and Worker.State.SUCCEEDED

In the next example, we will use these properties to add a progress loading indicator and messages about the end of the page loading:

// chapter9/web/LoadWorkerDemo.java
public void start(Stage primaryStage) {
    WebView webView = new WebView();
    WebEngine webEngine = webView.getEngine();
    webEngine.load("https://stackoverflow.com/questions/tagged/javafx");

    ProgressBar loadingBar = new ProgressBar(0);
    loadingBar.setMinWidth(400);

    // using binding to easily connect the worker and the progress bar
    loadingBar.progressProperty().bind(
            webEngine.getLoadWorker().progressProperty());

    webEngine.getLoadWorker().stateProperty().addListener(
            (observable, oldValue, newValue) -> {
                if (newValue == Worker.State.SUCCEEDED) {
                    System.out.println("Page was successfully loaded!");
                } else if (newValue == Worker.State.FAILED) {
                    System.out.println("Page loading has failed!");
                } 

            });

    VBox root = new VBox(5, loadingBar, webView);
    primaryStage.setTitle("JavaFX on SO");
    primaryStage.setScene(new Scene(root, 400, 300));
    primaryStage.show();
}

Here is a screenshot of the application in the middle of loading. Note the progress bar at the top:

Another way to wait for page loading is the workDone property:

webEngine.getLoadWorker().workDoneProperty().addListener((observable, oldValue, newValue) -> {
        if (newValue.intValue() == 100) {
                  // page is 100% loaded
        }
});