37. Fluent API 1

The buttons increment or decrement a counter.

There are two labels, first one is bound using if-then-else (using When) to see if number is 0 or greater. If so, it prints "positive". The number 0 is positive since the sign bit is 0 indicating a positive number.

The second label uses a .concat operation to join two Strings.

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package ex37;
 
import javafx.application.Application;
import javafx.beans.binding.When;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
 
public class Ex37 extends Application {
 
    @Override
    public void start(Stage primaryStage) {
 
        IntegerProperty labelNumber 
            = new SimpleIntegerProperty(0);
        
        Button inc = new Button("+");
        inc.setOnAction( e -> {
            labelNumber.set(labelNumber.get() + 1);
        });
        
        Button dec = new Button("-");
        dec.setOnAction( e -> { 
            labelNumber.set(labelNumber.get() - 1);
        });
        
        Label label1 = new Label();
        Label label2 = new Label();
        
        VBox root = new VBox(inc, dec, label1, label2);
        root.setSpacing(50);
        root.setAlignment(Pos.CENTER);
        root.setStyle("-fx-font-size: 16pt;"
                + "-fx-background-color: aliceblue;");
        
        label1.textProperty()
                .bind(new When(labelNumber
                        .greaterThanOrEqualTo(0))
                        .then("positive")
                        .otherwise("negative"));
        
        label2.textProperty()
                .bind(new SimpleStringProperty("Number: ")
                        .concat(labelNumber.asString()));
        
        Scene scene = new Scene(root, 400, 400);
        
        primaryStage.setTitle("Example 37. Fluent API 1");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
 
    public static void main(String[] args) {
        launch(args);
    }
}

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This is the output:

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