Bind textfield in JavaFX - javafx

Question

How to bind in JavaFx a textField with others textFields. For Example
textFieldTotal.textProperty.bind(Bindings.multiply(textFieldAmount.textProperty,
textFieldPrice.textProperty));

Answer 1

You question is pretty vague, but I'm going to take a guess. Basically, you need to create some additional Property and Binding objects.
First, create properties for your two TextField nodes. Then, you'll bind them using a StringConverter to convert the text entered into doubles.
Finally, create a "total" property that multiplies the two fields together and displays them in a Label.
Here's a very simple application to test out:
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.StringConverter;
import javafx.util.converter.DoubleStringConverter;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
// Simple Interface
VBox root = new VBox(10);
root.setAlignment(Pos.CENTER);
root.setPadding(new Insets(10));
// Quantity
HBox hBoxQuantity = new HBox(5);
hBoxQuantity.setAlignment(Pos.CENTER);
TextField txtQuantity = new TextField();
hBoxQuantity.getChildren().addAll(
new Label("Quantity:"),
txtQuantity
);
// Price
HBox hBoxPrice = new HBox(5);
hBoxPrice.setAlignment(Pos.CENTER);
TextField txtPrice = new TextField();
hBoxPrice.getChildren().addAll(
new Label("Price:"),
txtPrice
);
// Total
HBox hBoxTotal = new HBox(5);
hBoxTotal.setAlignment(Pos.CENTER);
Label lblTotal = new Label();
hBoxTotal.getChildren().addAll(
new Label("Total: $"),
lblTotal
);
// Properties used for bindings
DoubleProperty price = new SimpleDoubleProperty();
DoubleProperty quantity = new SimpleDoubleProperty();
DoubleProperty total = new SimpleDoubleProperty();
// Bind the total to price x quantity
total.bind(price.multiply(quantity));
// Setup the converters to get the input from the textfields
StringConverter<? extends Number> converter = new DoubleStringConverter();
// Bind the text field entries to their properties
Bindings.bindBidirectional(txtPrice.textProperty(), price, (StringConverter<Number>) converter);
Bindings.bindBidirectional(txtQuantity.textProperty(), quantity, (StringConverter<Number>) converter);
// Bind the total label
lblTotal.textProperty().bind(total.asString());
// Add all nodes to stage
root.getChildren().addAll(hBoxPrice, hBoxQuantity, hBoxTotal);
// Show the stage
primaryStage.setWidth(300);
primaryStage.setHeight(300);
primaryStage.setScene(new Scene(root));
primaryStage.setTitle("Sample");
primaryStage.show();
}
}
The Result:
Is this what you had in mind?
Note: This obviously does not include any error checking or restrictions on input, so you'll receive an error message if entering a non-numeric String in either TextField.