javafx : pass parameter to the eventhandler function in fxml file - javafx

Question

Is there a way to call the event handler method from the fxml file which holds parameter? please find the files:
My Fxml Looks like:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.image.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.cognizant.iotworkbench.View.AddImageController">
<children>
<Label layoutX="270.0" layoutY="14.0" text="Add Sensor" />
<BorderPane layoutY="-1.0" prefHeight="400.0" prefWidth="602.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<left>
<HBox fx:id="source" prefHeight="100.0" prefWidth="200.0" BorderPane.alignment="CENTER">
<children>
<ImageView fx:id="sourceimg" fitHeight="114.0" fitWidth="142.0" onDragDetected="#setUpGestureSource" pickOnBounds="true" preserveRatio="true">
<image>
<Image url="file:Images/Project.png" />
</image>
</ImageView>
</children>
</HBox>
</left>
<right>
<HBox fx:id="target" onDragDropped="#setUpGestureTarget" onDragOver="#setUpGestureTarget" prefHeight="100.0" prefWidth="200.0" BorderPane.alignment="CENTER" />
</right>
</BorderPane>
</children>
</AnchorPane>
My controller class looks like
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.ClipboardContent;
import javafx.scene.input.DragEvent;
import javafx.scene.input.Dragboard;
import javafx.scene.input.MouseEvent;
import javafx.scene.input.TransferMode;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.text.Text;
/**
* FXML Controller class
*
*/
public class AddImage implements Initializable,ControlledScreen {
ScreensController myController;
/**
* Initializes the controller class.
*/
#FXML
final HBox target=new HBox();
#FXML
final HBox source=new HBox();
#FXML
final ImageView sourceimg=new ImageView();
#FXML
public void setUpGestureSource()
{
System.out.println("source");
source.setOnDragDetected(new EventHandler <MouseEvent>() {
#Override
public void handle(MouseEvent event) {
/* drag was detected, start drag-and-drop gesture*/
System.out.println("onDragDetected");
/* allow MOVE transfer mode */
Dragboard db = source.startDragAndDrop(TransferMode.COPY);
/* put a string on dragboard */
ClipboardContent content = new ClipboardContent();
Image sourceImage = sourceimg.getImage();
content.putImage(sourceImage);
db.setContent(content);
event.consume();
}
});
}
#FXML
public void setUpGestureTarget(){
System.out.println("target");
target.setOnDragOver(new EventHandler <DragEvent>() {
#Override
public void handle(DragEvent event) {
Dragboard db = event.getDragboard();
if(db.hasImage()){
event.acceptTransferModes(TransferMode.COPY);
}
event.consume();
}
});
target.setOnDragDropped(new EventHandler <DragEvent>() {
#Override
public void handle(DragEvent event) {
Dragboard db = event.getDragboard();
if(db.hasImage()){
insertImage(db.getImage(), target);
event.setDropCompleted(true);
}else{
event.setDropCompleted(false);
}
event.consume();
}
});
}
void insertImage(Image i, HBox hb){
ImageView iv = new ImageView();
iv.setImage(i);
setUpGestureSource();
hb.getChildren().add(iv);
}
#Override
public void setScreenParent(ScreensController screenParent) {
myController=screenParent;
}
#Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
}
Drag and Drop event is not getting fired. I dont know what's wrong with the code. Please help

Answer 1

All methods that are annotated with #FXML may or may not have a parameter. If you need a parameter, you can directly pass the specific Event as a parameter to the method.
Let us take an example and say you have an onDragOver event added for a HBox in the fxml.
<HBox fx:id="targetBox" onDragOver="#setupGestureTarget">
...
</HBox>
Then you may have a method which does the needful inside the controller class.
#FXML
public void setupGestureTarget(DragEvent event) {
Dragboard db = event.getDragboard();
if(db.hasImage()){
event.acceptTransferModes(TransferMode.COPY);
}
event.consume();
}
If you need the source node for which the method was called, you can get an access to it by getSource() of the event, then type-caste it to Node.
public void setupGestureTarget(DragEvent event) {
...
((Node)event.getSource()).setId("myHbox");
System.out.println(targetBox.getId()); // Prints - myHbox
}
Note : For using methods specific to HBox, you can type-caste it to a HBox instead of a Node.
EDIT - As per user comments and updates
There are multiple issues with your approach. Let me address them all.
1.Values to the fields annotated with #FXML are injected while the FXML is getting loaded and should not carry new keyword.
#FXML
final HBox target=new HBox();
should be replaced by
#FXML
final HBox target;
2.As I have already stated your method can have a parameter which defines the Event. So the methods setUpGestureSource() and setUpGestureTarget() can be defined as :
#FXML
public void setUpGestureSource(DragEvent event) {
...
}
#FXML
public void setUpGestureTarget(DragEvent event) {
...
}
3.The method setUpGestureSource is called when a drag-event occurs on the ImageView, so you don't need to add another EventHandler for it.
#FXML
public void setUpGestureSource(MouseEvent event) {
/* drag was detected, start drag-and-drop gesture*/
System.out.println("onDragDetected");
* allow MOVE transfer mode */
Dragboard db = source.startDragAndDrop(TransferMode.COPY);
/* put a string on dragboard */
ClipboardContent content = new ClipboardContent();
Image sourceImage = sourceimg.getImage();
content.putImage(sourceImage);
db.setContent(content);
event.consume();
}
Similarly, change the other method as well.