Java-Buddy

Example to implement ChangeListener() to monitor StringProperty change.

package javafx_propertylistener;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
/**
 *
 * @web http://java-buddy.blogspot.com/
 */
public class JavaFX_PropertyListener extends Application {
 
 @Override
 public void start(Stage primaryStage) {
 
 StringProperty stringProperty = new SimpleStringProperty();
 
 TextField textInput = new TextField();
 Label labelOutput1 = new Label();
 Label labelObservable = new Label();
 Label labelOldvalue = new Label();
 Label labelNewvalue = new Label();
 
 labelOutput1.textProperty().bind(textInput.textProperty());
 
 Button btn = new Button();
 btn.setText("Updated");
 btn.setOnAction(new EventHandler<ActionEvent>() {
 
 @Override
 public void handle(ActionEvent event) {
 stringProperty.set(textInput.getText());
 }
 });
 
 // add listener for stringProperty
 // to be called when stringProperty changed
 stringProperty.addListener(new ChangeListener(){
 @Override
 public void changed(ObservableValue observable, Object oldValue, Object newValue) {
 labelObservable.setText((String)observable.getValue());
 labelOldvalue.setText((String)oldValue);
 labelNewvalue.setText((String)newValue);
 }
 });
 
 VBox vBox = new VBox();
 vBox.getChildren().addAll(textInput, labelOutput1, btn, 
 labelObservable, labelOldvalue, labelNewvalue);
 
 StackPane root = new StackPane();
 root.getChildren().add(vBox);
 
 Scene scene = new Scene(root, 300, 250);
 
 primaryStage.setTitle("Java-Buddy");
 primaryStage.setScene(scene);
 primaryStage.show();
 }
 public static void main(String[] args) {
 launch(args);
 }
 
}

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