Adding eventhandler to treeitems in javafx [duplicate] - javafx

Question

The fxml file is as follows (headers omitted):
<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity"
minWidth="-Infinity" prefHeight="600.0" prefWidth="800.0"
xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1"
fx:id="pane"
fx:controller="com.github.parboiled1.grappa.debugger.mainwindow.MainWindowUi">
<top>
<MenuBar BorderPane.alignment="CENTER">
<Menu mnemonicParsing="false" text="File">
<MenuItem fx:id="loadInput" mnemonicParsing="false"
text="Load file" onAction="#loadFileEvent"/>
<MenuItem fx:id="parse" mnemonicParsing="false"
text="Parse" onAction="#parseEvent"/>
<MenuItem fx:id="closeButton" mnemonicParsing="false"
text="Close" onAction="#closeWindowEvent"/>
</Menu>
</MenuBar>
</top>
<center>
<SplitPane dividerPositions="0.5" prefHeight="160.0" prefWidth="200.0"
BorderPane.alignment="CENTER">
<SplitPane dividerPositions="0.5" orientation="VERTICAL">
<TreeView fx:id="traceTree" prefHeight="200.0"
prefWidth="200.0" editable="false"/>
<TextArea fx:id="traceDetail" prefHeight="200.0"
prefWidth="200.0"/>
</SplitPane>
<TextArea fx:id="inputText" prefHeight="200.0" prefWidth="200.0"/>
</SplitPane>
</center>
</BorderPane>
I can set the root of the TreeView with no problem at all. The tree is updated with no problem.
The problem I have is that I cannot manage to have an event fired on a given item in the view. I tried and added a onMouseClicked event with a simple System.out.println() and I can see the event being fired, whichever item I click in the tree. But I cannot manage to get the item which has been clicked in the view at all.
How do I do that?

Answer 1

Register a mouse listener with each tree cell, using a cell factory. I don't know the data type you have in your TreeView, but if it were String it might look something like this:
// Controller class:
public class MainWindowUi {
#FXML
private TreeView<String> traceTree ;
// ...
public void initialize() {
traceTree.setCellFactory(tree -> {
TreeCell<String> cell = new TreeCell<String>() {
#Override
public void updateItem(String item, boolean empty) {
super.updateItem(item, empty) ;
if (empty) {
setText(null);
} else {
setText(item);
}
}
};
cell.setOnMouseClicked(event -> {
if (! cell.isEmpty()) {
TreeItem<String> treeItem = cell.getTreeItem();
// do whatever you need with the treeItem...
}
});
return cell ;
});
}
// ...
}