Chapter 12, Problem 12AW

Explanation of Solution

Event handler:

• The event handler is nothing but an object that responds to the events.
• A particular method in the event handler is called if an event source is connected to the event handler. The object of the event is passed as the argument to that method.
  • This process is known as event firing.
• The event handler class should implement the “EventHandler” interface.
  • This interface is in the package “javafx.event”.

Algorithm to register an instance of the class with “myButton” control:

Step 1: Register the instance of the class with “myButton” control. It is done with the help of the statement “setOnAction (new ButtonClickHandler ())”.

Statement to register an instance of the class with “myButton” control:

//Register the event handler

myButton.setOnAction(new ButtonClickHandler ());

Example program:

The statement to register the instance of the class with “myButton” control is highlighted.

//Import required packages

import javafx.application.Application;

import javafx.event.ActionEvent;

import javafx.event.EventHandler;

import javafx.geometry.Pos;

import javafx.geometry.Insets;

import javafx.stage.Stage;

import javafx.scene.Scene;

import javafx.scene.layout.VBox;

import javafx.scene.control.Label;

import javafx.scene.control.Button;

//Declare the main class

public class Example extends Application

{

//Create a label

private Label outputLabel;

//Declare the main method

public static void main(String[] args)

{

// Launch the application.

launch(args);

}

//Override the start method

@Override

public void start(Stage primaryStage)

{

//Create a label

outputLabel = new Label();

//Create a button

Button myButton = new Button ("Click Me");

//Register the event handler

myButton...