JavaFX ObservableList toTableview via Task Thread - multithreading

Question

I am building a multiscreen JavaFX app with data being pulled from a SQL database to ObservableLists and displayed in the interface via Tableview. Because of the multiscreen nature of the app, I am trying to initialize the data from the ObservableList to the Tableview via the controller. The SQL pull to ObservableList is done via a Task on a new thread. When I include the sqlCSEditTbl.itemsProperty().setValue((ObservableList) csSQLList) in the Task method nothing is displayed in the TableView when I run the program. If I place the code outside the Task method,the particular screen will not display. I don't know what I am missing here to be able to get the data to display on the particular screen. I've debugged the SQL to ObservableList and the data is being properly stored in the ObservableList. The problem is getting it from the ObservableList to the Tableview interface. Any help would be greatly appreciated. Thank you!
App Edit Screen Screenshot
SQLCalcScript Array Model
package model.calcs;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
/**
* Created by jdsmith on 2/17/2016.
*/
public class SQLCalcScripts {
private final IntegerProperty calcScriptID;
private final IntegerProperty calcScriptIndex;
private final StringProperty calcScriptName;
private final StringProperty calcScriptServer;
private final StringProperty calcScriptApp;
private final StringProperty calcScriptGroup;
public SQLCalcScripts() {
this(null, null, null, null, null, null);
}
public SQLCalcScripts(Integer calcScriptID, Integer calcScriptIndex, String calcScriptName, String calcScriptServer, String calcScriptApp, String calcScriptGroup) {
this.calcScriptID = new SimpleIntegerProperty(calcScriptID);
this.calcScriptIndex = new SimpleIntegerProperty(calcScriptIndex);
this.calcScriptName = new SimpleStringProperty(calcScriptName);
this.calcScriptServer = new SimpleStringProperty(calcScriptServer);
this.calcScriptApp = new SimpleStringProperty(calcScriptApp);
this.calcScriptGroup = new SimpleStringProperty(calcScriptGroup);
this.calcScriptID.addListener((e) -> System.out.println("ID changed to " + this.calcScriptID.get()));
this.calcScriptIndex.addListener((e) -> System.out.println("ID changed to " + this.calcScriptIndex.get()));
this.calcScriptName.addListener((e) -> System.out.println("ID changed to " + this.calcScriptName.get()));
this.calcScriptServer.addListener((e) -> System.out.println("ID changed to " + this.calcScriptServer.get()));
this.calcScriptApp.addListener((e) -> System.out.println("ID changed to " + this.calcScriptApp.get()));
this.calcScriptGroup.addListener((e) -> System.out.println("ID changed to " + this.calcScriptGroup.get()));
}
// Getters and Setters for Calc Script
public Integer getCalcScriptID() {
return calcScriptID.get();
}
public void setCalcScriptID(Integer calcScriptID) {
this.calcScriptID.set(calcScriptID);
}
public IntegerProperty calcScriptIDProperty() {
return calcScriptID;
}
public Integer getCalcScriptIndex() {
return calcScriptIndex.get();
}
public void setCalcScriptIndex(Integer calcScriptIndex) {
this.calcScriptIndex.set(calcScriptIndex);
}
public IntegerProperty calcScriptIndexProperty() {
return calcScriptIndex;
}
public String getCalcScriptName() {
return calcScriptName.get();
}
public void setCalcScriptName(String calcScriptName) {
this.calcScriptName.set(calcScriptName);
}
public StringProperty calcScriptNameProperty() {
return calcScriptName;
}
public String getCalcScriptServer() {
return calcScriptServer.get();
}
public void setCalcScriptServer(String calcScriptServer) {
this.calcScriptServer.set(calcScriptServer);
}
public StringProperty calcScriptServerProperty() {
return calcScriptServer;
}
public String getCalcScriptApp() {
return calcScriptApp.get();
}
public void setCalcScriptApp(String calcScriptApp) {
this.calcScriptApp.set(calcScriptApp);
}
public StringProperty calcScriptAppProperty() {
return calcScriptApp;
}
public String getCalcScriptGroup() {
return calcScriptGroup.get();
}
public void setCalcScriptGroup(String calcScriptGroup) {
this.calcScriptGroup.set(calcScriptGroup);
}
public StringProperty calcScriptGroupProperty() {
return calcScriptGroup;
}
}
csEditInterface.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.text.*?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="1080.0" prefWidth="1920.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="essapp.csEditController">
<children>
<VBox alignment="TOP_CENTER" prefHeight="200.0" prefWidth="100.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<children>
<Label alignment="CENTER" contentDisplay="CENTER" text="Calculation Script Editor">
<font>
<Font name="System Bold" size="36.0" />
</font>
</Label>
<ScrollPane fitToHeight="true" fitToWidth="true" pannable="true" prefHeight="800.0" prefWidth="717.0">
<content>
<AnchorPane prefHeight="200.0" prefWidth="717.0">
<children>
<TableView editable="true" prefHeight="200.0" prefWidth="200.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<columns>
<TableColumn fx:id="csEditID" editable="false" prefWidth="100.0" sortable="false" text="ID" />
<TableColumn fx:id="csEditIndex" prefWidth="100.0" text="Index" />
<TableColumn fx:id="csEditName" prefWidth="250.0" sortable="false" text="Name" />
<TableColumn fx:id="csEditServer" editable="false" prefWidth="300.0" sortable="false" text="Server" />
<TableColumn fx:id="csEditApp" editable="false" prefWidth="250.0" sortable="false" text="Application" />
<TableColumn fx:id="csEditGroup" prefWidth="400.0" sortable="false" text="Calc Group" />
</columns>
</TableView>
</children>
</AnchorPane>
</content>
<VBox.margin>
<Insets left="50.0" right="50.0" top="50.0" />
</VBox.margin>
</ScrollPane>
<Button fx:id="csEditOkBtn" defaultButton="true" mnemonicParsing="false" onAction="#createTbl" prefHeight="25.0" prefWidth="151.0" text="Commit Changes">
<VBox.margin>
<Insets top="50.0" />
</VBox.margin>
</Button>
<Button fx:id="csEditExitBtn" cancelButton="true" mnemonicParsing="false" onAction="#goToCSInt" prefHeight="25.0" prefWidth="150.0" text="Cancel">
<VBox.margin>
<Insets top="25.0" />
</VBox.margin>
</Button>
</children>
</VBox>
</children>
</AnchorPane>
csEditController Code:
package essapp;
import com.sun.javafx.tk.Toolkit;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.*;
import javafx.scene.control.cell.ComboBoxTableCell;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.util.StringConverter;
import javafx.util.converter.DefaultStringConverter;
import model.calcs.*;
import java.net.URL;
import java.util.Map;
import java.util.ResourceBundle;
import static javafx.scene.input.KeyCode.T;
#SuppressWarnings("Duplicates")
public class csEditController implements Initializable, ControlledScreen {
ScreensController myController;
ObservableList<SQLCalcScripts> csEditCSList = FXCollections.observableArrayList();
ObservableList<CalcScripts> csEditEssSQL = FXCollections.observableArrayList();
/**
* Initializes the controller class.
*/
#Override
public void initialize(URL url, ResourceBundle rb) {
//Add SQL data to TableView
Task task = new Task<Void>() {
#Override
public Void call() throws Exception {
SQL2CalcScripts csSQLList = new SQL2CalcScripts();
csSQLList.sqlCalc("http://TEST-HYPRPT01:13080/aps/JAPI","GNLESB",csEditCSList);
sqlCSEditTbl.itemsProperty().setValue((ObservableList<SQLCalcScripts>) csSQLList);
return null;
}
};
// sqlCSEditTbl.itemsProperty().bind(task.valueProperty());
// sqlCSEditTbl.setItems(csEditCSList);
new Thread(task).start();
// Initialize table with columns
csEditID.setCellValueFactory(cellData -> cellData.getValue().calcScriptIDProperty().asObject());
csEditIndex.setCellValueFactory(cellData -> cellData.getValue().calcScriptIndexProperty().asObject());
csEditName.setCellValueFactory(cellData -> cellData.getValue().calcScriptNameProperty());
csEditServer.setCellValueFactory(cellData -> cellData.getValue().calcScriptServerProperty());
csEditApp.setCellValueFactory(cellData -> cellData.getValue().calcScriptAppProperty());
csEditGroup.setCellValueFactory(cellData -> cellData.getValue().calcScriptGroupProperty());
// TableView Calc Group ComboBox
ObservableList<String> csGroupList = FXCollections.observableArrayList("Supplement", "Wrapper", "Board Book");
csEditGroup.setCellFactory(ComboBoxTableCell.forTableColumn(new DefaultStringConverter(), csGroupList));
csEditGroup.setOnEditCommit(
(TableColumn.CellEditEvent<SQLCalcScripts,String> cb) -> {
((SQLCalcScripts) cb.getTableView().getItems().get(
cb.getTablePosition().getRow()
)).setCalcScriptGroup(cb.getNewValue());
}
);
}
public void setScreenParent(ScreensController screenParent){
myController = screenParent;
}
#FXML // ResourceBundle that was given to the FXMLLoader
private ResourceBundle resources;
#FXML // URL location of the FXML file that was given to the FXMLLoader
private URL location;
#FXML // fx:id="sqlCSEditTbl"
private TableView<SQLCalcScripts> sqlCSEditTbl; // Value injected by FXMLLoader
#FXML // fx:id="csEditGroup"
private TableColumn<SQLCalcScripts, String> csEditGroup; // Value injected by FXMLLoader
#FXML // fx:id="csEditExitBtn"
private Button csEditExitBtn; // Value injected by FXMLLoader
#FXML // fx:id="csEditServer"
private TableColumn<SQLCalcScripts, String> csEditServer; // Value injected by FXMLLoader
#FXML // fx:id="csEditID"
private TableColumn<SQLCalcScripts, Integer> csEditID; // Value injected by FXMLLoader
#FXML // fx:id="csEditIndex"
private TableColumn<SQLCalcScripts, Integer> csEditIndex; // Value injected by FXMLLoader
#FXML // fx:id="csEditOkBtn"
private Button csEditOkBtn; // Value injected by FXMLLoader
#FXML // fx:id="csEditApp"
private TableColumn<SQLCalcScripts, String> csEditApp; // Value injected by FXMLLoader
#FXML // fx:id="csEditName"
private TableColumn<SQLCalcScripts, String> csEditName; // Value injected by FXMLLoader
#FXML
private void goToCSInt(ActionEvent event){
myController.setScreen(ScreensFramework.calcScriptInterfaceID);
}
// #FXML
// private void createTbl(ActionEvent event) {
// sqlCSEditTbl.setItems(csEditCSList);
// }
}
ControlledScreen class Code:
package sample;
/**
* Created by jdsmith on 4/21/2016.
*/
public interface ControlledScreen {
//This method will allow the injection of the Parent ScreenPane
public void setScreenParent(ScreensController screenPage);
}
ScreensController class Code:
package essapp;
import java.util.HashMap;
import javafx.animation.KeyFrame;
import javafx.animation.KeyValue;
import javafx.animation.Timeline;
import javafx.beans.property.DoubleProperty;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.layout.StackPane;
import javafx.util.Duration;
/**
* Created by jdsmith on 1/7/2016.
*/
public class ScreensController extends StackPane {
//Holds the screens to be displayed
private HashMap<String, Node> screens = new HashMap<>();
public ScreensController() {
super();
}
//Add the screen to the collection
public void addScreen(String name, Node screen) {
screens.put(name, screen);
}
//Returns the Node with the appropriate name
public Node getScreen(String name) {
return screens.get(name);
}
//Loads the fxml file, add the screen to the screens collection and
//finally injects the screenPane to the controller.
public boolean loadScreen(String name, String resource) {
try {
FXMLLoader myLoader = new FXMLLoader(getClass().getResource(resource));
Parent loadScreen = (Parent) myLoader.load();
ControlledScreen myScreenControler = ((ControlledScreen) myLoader.getController());
myScreenControler.setScreenParent(this);
addScreen(name, loadScreen);
return true;
} catch (Exception e) {
System.out.println(e.getMessage());
return false;
}
}
//This method tries to displayed the screen with a predefined name.
//First it makes sure the screen has been already loaded. Then if there is more than
//one screen the new screen is been added second, and then the current screen is removed.
// If there isn't any screen being displayed, the new screen is just added to the root.
public boolean setScreen(final String name) {
if (screens.get(name) != null) { //screen loaded
final DoubleProperty opacity = opacityProperty();
if (!getChildren().isEmpty()) { //if there is more than one screen
Timeline fade = new Timeline(
new KeyFrame(Duration.ZERO, new KeyValue(opacity, 1.0)),
new KeyFrame(new Duration(1000), new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent t) {
getChildren().remove(0); //remove the displayed screen
getChildren().add(0, screens.get(name)); //add the screen
Timeline fadeIn = new Timeline(
new KeyFrame(Duration.ZERO, new KeyValue(opacity, 0.0)),
new KeyFrame(new Duration(800), new KeyValue(opacity, 1.0)));
fadeIn.play();
}
}, new KeyValue(opacity, 0.0)));
fade.play();
} else {
setOpacity(0.0);
getChildren().add(screens.get(name)); //no one else been displayed, then just show
Timeline fadeIn = new Timeline(
new KeyFrame(Duration.ZERO, new KeyValue(opacity, 0.0)),
new KeyFrame(new Duration(2500), new KeyValue(opacity, 1.0)));
fadeIn.play();
}
return true;
} else {
System.out.println("screen hasn't been loaded!!! \n");
return false;
}
/*Node screenToRemove;
if(screens.get(name) != null){ //screen loaded
if(!getChildren().isEmpty()){ //if there is more than one screen
getChildren().add(0, screens.get(name)); //add the screen
screenToRemove = getChildren().get(1);
getChildren().remove(1); //remove the displayed screen
}else{
getChildren().add(screens.get(name)); //no one else been displayed, then just show
}
return true;
}else {
System.out.println("screen hasn't been loaded!!! \n");
return false;
}*/
}
//This method will remove the screen with the given name from the collection of screens
public boolean unloadScreen(String name) {
if (screens.remove(name) == null) {
System.out.println("Screen didn't exist");
return false;
} else {
return true;
}
}
}
ScreensFramework Main App Code:
package essapp;
import javafx.application.Application;
import javafx.geometry.Rectangle2D;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.stage.Screen;
import javafx.stage.Stage;
public class ScreensFramework extends Application {
public static String mainInterfaceID = "main";
public static String mainInterfaceFile = "mainInterface.fxml";
public static String msaInterfaceID = "msa";
public static String msaInterfaceFile = "msaInterface.fxml";
public static String creditRatingInterfaceID = "credit";
public static String creditRatingInterfaceFile = "creditRatingInterface.fxml";
public static String calcScriptEditID = "csEdit";
public static String calcScriptEditFile = "csEditInterface.fxml";
public static String calcScriptInterfaceID = "calc";
public static String calcScriptInterfaceFile = "calcScriptInterface.fxml";
public static String subVarInterfaceID = "subvar";
public static String subVarInterfaceFile = "subVarInterface.fxml";
#Override
public void start(Stage primaryStage) {
ScreensController mainContainer = new ScreensController();
mainContainer.loadScreen(ScreensFramework.mainInterfaceID, ScreensFramework.mainInterfaceFile);
mainContainer.loadScreen(ScreensFramework.calcScriptInterfaceID, ScreensFramework.calcScriptInterfaceFile);
mainContainer.loadScreen(ScreensFramework.calcScriptEditID, ScreensFramework.calcScriptEditFile);
mainContainer.loadScreen(ScreensFramework.subVarInterfaceID, ScreensFramework.subVarInterfaceFile);
mainContainer.loadScreen(ScreensFramework.msaInterfaceID, ScreensFramework.msaInterfaceFile);
mainContainer.loadScreen(ScreensFramework.creditRatingInterfaceID, ScreensFramework.creditRatingInterfaceFile);
mainContainer.setScreen(ScreensFramework.mainInterfaceID);
mainContainer.prefHeightProperty().bind(primaryStage.heightProperty());
mainContainer.prefWidthProperty().bind(primaryStage.widthProperty());
mainContainer.setCenterShape(true);
mainContainer.setScaleShape(true);
Group root = new Group();
root.getChildren().addAll(mainContainer);
Scene scene = new Scene(root);
Screen screen = Screen.getPrimary();
Rectangle2D bounds = screen.getVisualBounds();
primaryStage.setWidth(bounds.getWidth());
primaryStage.setHeight(bounds.getHeight());
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

Answer 1

When you call
sqlCSEditTbl.itemsProperty().setValue(...);
you are updating the UI (by updating the items displayed in the table). Like (almost?) all UI toolkits, JavaFX is single-threaded: updates to the UI can only happen on the FX Application Thread. Doing this in the Task, which is being executed on a background thread, will throw a IllegalStateException; so your call method never completes and you never see the update to the table.
The usual way to do this is to return the data from your call method:
Task<List<SQLCalcScripts>> task = new Task<List<SQLCalcScripts>>() {
#Override
public List<SQLCalcScripts> call() throws Exception {
List<SQLCalcScripts> data = /* get data.... */ ;
return data;
}
};
when the task completes, the value property is set to the value returned from the call method, so you can now do:
task.setOnSucceeded(e -> sqlCSEditTbl.getItems().setAll(task.getValue()));
It's probably a good idea to log any exceptions that occur with
task.setOnFailed(e -> task.getException().printStackTrace());
Then as before launch the task with
new Thread(task).start();