onAction for textfield in javafx - javafx

Question

I have JavaFX TextField in my code and would like to add an action to different events on the TextField.
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.event.EventType;
import javafx.geometry.Pos;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.control.Tooltip;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.*;
import javafx.scene.text.Font;
import javafx.stage.FileChooser;
import javafx.stage.Stage;
import java.io.File;
import javafx.beans.value.ChangeListener;
/* Input from user */
weightTF = new TextField();
weightTF.setMaxWidth(36);
activeInsulinTF = new TextField();
activeInsulinTF.setMaxWidth(36);
VBox inputBox = new VBox();
inputBox.setFillWidth(false);
inputBox.setAlignment(Pos.CENTER);
inputBox.getChildren().add(weightTF);
inputBox.getChildren().add(activeInsulinTF);
inputBox.setSpacing(8);
// Add onAction for the texfields
menuHBox.getChildren().add(inputBox);
weightTF.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
double weight = Double.parseDouble(weightTF.getText());
Main.state.setWeight(weight);
System.out.println("Entered weight: " + weight);
}
});
Today I only get an action when I press enter after writing some text in the TextField. How can I add an action for handling a tab press? Also, how to react when the TextField looses focus with a mouse click?
As I read the documentation it should be possible:
https://docs.oracle.com/javase/8/javafx/api/javafx/scene/control/TextField.html
Hope someone can help me :)

Answer 1

There are a couple of convenience methods to do exactly that, for example
weightTF.setOnKeyPressed(new EventHandler<KeyEvent>() {
#Override
public void handle(KeyEvent event) {
// do stuff
}
});
this executes whenever a key is pressed in the TextField. You might want to check if the pressed key was a specific one. This can be achieved by
if(event.getCode() == KeyCode.TAB){
// do stuff
}
for example. If you are using NetBeans or some other IDE, you can take a look at the convenience methods by pressing the autocomplete shortcut after having typed "weightTF.", which will show you all of the available methods. The methods I am talking about start with setOn...
Hope that helped :)

Answer 2

It sounds from your question as though you are really interested in knowing when the user moves focus from the text field to another control. This can happen typically if the user presses Tab, or clicks the mouse on another control, though technically this behavior is platform-dependent. It can also happen programmatically.
The problems with using "low-level" event handlers are (1) that in theory you would have to register a mouse listener with all other controls; (2) that you rely on the same keystrokes being used on all platforms for focus traversal; and (3) that if you were to add functionality which required programmatic focus traversal (i.e. you have code like someOtherControl.requestFocus() anywhere), your event listener will not be notified.
The sure-fire way to respond if a text field loses focus is simply to register a listener with its focusedProperty():
weightTF.focusedProperty().addListener((obs, wasFocused, isNowFocused) -> {
if (! isNowFocused) {
// text field has lost focus...
System.out.println(weightTF.getText());
}
});
Note also that the Scene has a focusOwnerProperty, which is similarly observable and contains a reference to the node in the scene that currently has focus. You could potentially use this property instead for a more general listener that handled moving focus away from any text field.