Event Programming in JavaFX stony brook cs

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Event Programming,Procedural programming is executed in. procedural statement order,In event driven programming code is executed. upon activation of events,Operating Systems constantly monitor events. Ex keystrokes mouse clicks etc,sorts out these events. reports them to the appropriate programs,c Paul Fodor and Pearson Inc.
Where do we come in,For each control button combo box etc. define an event handler,construct an instance of event handler. tell the control who its event handler is,Event Handler. code with response to event,a k a event listener,c Paul Fodor and Pearson Inc. Java s Event Handling,An event source is a GUI control.
JavaFX Button ChoiceBox ListView etc, http docs oracle com javase 8 javafx user interface tutorial ui controls htm. different types of sources,can detect different types of events. can register different types of listeners handlers. c Paul Fodor and Pearson Inc,Java s Event Handling. When the user interacts with a control source,an event object is constructed. the event object is sent to all registered listener objects. the listener object handler responds as you defined it to. c Paul Fodor and Pearson Inc,Event Listeners Event Handler.
Defined by you the application programmer,you customize the response. Inheritance Polymorphism,You define your own listener class. implement the appropriate interface,define responses in all necessary methods. c Paul Fodor and Pearson Inc,Event Objects,Contain information about the event. location of mouse click,event source that was interacted with.
Listeners use them to properly respond,different methods inside a listener object can. react differently to different types of interactions. c Paul Fodor and Pearson Inc,import javafx application Application. import javafx stage Stage,import javafx scene Scene. import javafx scene layout HBox,import javafx scene control Button. import javafx event ActionEvent,import javafx event EventHandler.
import javafx geometry Pos,public class HandleEvent extends Application. public void start Stage primaryStage,HBox pane new HBox 10. Button btOK new Button OK,Button btCancel new Button Cancel. OKHandlerClass handler1 new OKHandlerClass,btOK setOnAction handler1. CancelHandlerClass handler2 new CancelHandlerClass. btCancel setOnAction handler2,pane getChildren addAll btOK btCancel.
Scene scene new Scene pane,primaryStage setScene scene primaryStage show. class OKHandlerClass implements EventHandler ActionEvent. public void handle ActionEvent e,System out println OK button clicked. class CancelHandlerClass implements EventHandler ActionEvent. public void handle ActionEvent e,8 System out println Cancel button clicked. c Paul Fodor and Pearson Inc,Handling GUI Events,Source object button. An event is generated by external user actions such as mouse movements. mouse clicks or keystrokes, An event can be defined as a type of signal to the program that.
something has happened, Listener object contains a method for processing the event. c Paul Fodor and Pearson Inc,Event Classes,c Paul Fodor and Pearson Inc. Event Information,An event object contains whatever properties are. pertinent to the event, the source object of the event using the getSource. instance method in the EventObject class,The subclasses of EventObject deal with special.
types of events such as button actions window,events component events mouse movements. and keystrokes,c Paul Fodor and Pearson Inc,Selected User Actions and Handlers. c Paul Fodor and Pearson Inc,The Delegation Model,c Paul Fodor and Pearson Inc. ControlCircle program that uses two buttons to control the size of a circle. import javafx application Application,import javafx stage Stage. import javafx scene Scene,import javafx scene layout StackPane.
import javafx scene layout HBox,import javafx scene layout BorderPane. import javafx scene control Button,import javafx scene paint Color. import javafx scene shape Circle,import javafx event ActionEvent. import javafx event EventHandler,import javafx geometry Pos. public class ControlCircle extends Application,private CirclePane circlePane new CirclePane.
public void start Stage primaryStage,HBox hBox new HBox. Button btEnlarge new Button Enlarge,Button btShrink new Button Shrink. hBox getChildren add btEnlarge,hBox getChildren add btShrink. btEnlarge setOnAction new EnlargeHandler,BorderPane borderPane new BorderPane. borderPane setCenter circlePane,borderPane setBottom hBox.
BorderPane setAlignment hBox Pos CENTER,Scene scene new Scene borderPane 200 150. 14 primaryStage setScene scene primaryStage show,c Paul Fodor and Pearson Inc. ControlCircle program that uses two buttons to control the size of a circle. Inner Class, class EnlargeHandler implements EventHandler ActionEvent. public void handle ActionEvent e,circlePane enlarge. class CirclePane extends StackPane,private Circle circle new Circle 50.
public CirclePane,getChildren add circle,circle setStroke Color BLACK. circle setFill Color WHITE,public void enlarge,circle setRadius circle getRadius 2. public void shrink,circle setRadius circle getRadius 2. circle getRadius 2 circle getRadius,c Paul Fodor and Pearson Inc. Event Programming in JavaFX c Paul Fodor and Pearson Inc Event Programming btEnlarge setOn Action e gt Code fo r processing event e

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