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null point exception while changing text of fxml label in javafx

public class SerialCommunicationController{
#FXML public Label tempReading;
#FXML public Label errorReading;
private final Logger logger = LoggerFactory.getLogger(getClass());
private ArduinoInterfaceControl arduinoInterfaceControl;
private Stage stage;
private String prop;
private String inte;
private String deri;
private boolean lastCommandSuccessful;
public static final String LOCAL_SIMULATOR = "Local Simulator";
private String[] params;
private ArduinoInterfaceControl arduinoInterface;
public SerialCommunicationController() {
}
public SerialCommunicationController(String cmd){
setValues(cmd);
}
public void setValues(String readings){
String[] params = readings.split("\\s+");
// something went wrong, just decode to blank.
if(params.length < 1) {
lastCommandSuccessful = false;
}
else {
tempReading.setText(params[0]);
errorReading.setText(params[1]);
// successful command received.
lastCommandSuccessful = Boolean.valueOf(params[1]);
}
}
}
Hi Guys i am getting NullPointException when trying to do tempReading.setText() and errorReading.setText(). I have defined default values of label text in my fxml file.

It seems that both tempReading and errorReading are null.
Perhaps binding to the FXML is incorrect?
Make sure the fx:id in the FXML file matches the names of your Label fields in the Java class.

Clean statement for value passing with afterburner fx in JavaFX?

I use the afterburner.fx framework for the javafx program as follows,
NameModel used for sharing the state between views or the implementation of business logic.
public class NameModel {
private final StringProperty name = new SimpleStringProperty();
public String getName() {
return name.get();
}
public void setName(String value) {
name.set(value);
}
public StringProperty nameProperty() {
return name;
}
}
SchoolPresenter I used to enter the value for NameModel.If the name in Model get value starting with character
starts with "A",I pass that name to ClassAPresenter and it is similar to names starting with character B, C ...for ClassB,ClassC...
public class SchoolPresenter implements Initializable {
#FXML
private StackPane stackPane;
#Inject NameModel nameModel;
private ClassAView classAView;
private ClassBView classBView;
private ClassCView classCView;
.............................
private ClassNView classNView;
#FXML
void txtName(ActionEvent event) {
String name=txtName.getText();
if (!name.isEmpty()) {
//My program runs fine not wrong but
//If I have N classes, and with declarations for the same classes below
//the program will be very confusing
//Please help me to collapse my code
if(name.startWith("A")){
if (classAView == null) {
classAView = new ClassAView();
ClassAPresenter classAPresenter = (ClassAPresenter) classAView.getPresenter();
classAPresenter.initNameModel(nameModel);
stackPane.getChildren().add(classAView.getView());
}
}else if(name.startWith("B")){
classBView = new ClassBView();
ClassBPresenter classAPresenter = (ClassBPresenter) classBView.getPresenter();
classBPresenter.initNameModel(nameModel);
stackPane.getChildren().add(classBView.getView());
}else if.............//
nameModel.setName(txtName.getText());
}
}
}
The ClassAPresenter, ClassBPresenter ...ClassNPresenter is structured as follows
public class ClassAPresenter implements Initializable {
private NameModel nameModel;
public void initDomainModel(NameModel nameModel) {
// ensure model is only set once:
if (this.nameModel != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.nameModel = nameModel;
}
}

JavaFX set textfields from current controller to the next controller

Im fairly new to both stackoverflow and javafx so please be nice.
Description of what Im doing:
I am making a simple quiz game. First window is just a like a welcome/start screen, when that button is clicked we get to the second screen where all the category buttons are, when one of them is clicked it will randomly pick a question of that kind of category user has selected and the third and last window will appear with the questions category as a label, question as textfield and answear as textfield.
Problem:
Whenever a category is clicked I need that current controller to set the next controllers textfields and label. I havent come to far with this. I just get a nullpointerexception when im calling the setQuestion method in the second controller, FXMLCategoriesDocumentController, when I tried to debug it it just says that the instantiated "questControll" is null all the time, and the "questControll.question/category/answear" is referenced from a null object
Code:
second controller
public class FXMLCategoriesDocumentController implements Initializable {
/**
* Initializes the controller class.
*/
private FXMLQuestionDocumentController questControll;
private Question quest;
#FXML
private void geografButtonAction(ActionEvent event) {
try {
FXMLLoader fxmlQuestLoader = new FXMLLoader(getClass().getResource("FXMLQuestionDocument.fxml"));
this.questControll = fxmlQuestLoader.<FXMLQuestionDocumentController>getController();
quest = new Question("Geografi", "Vad heter Sveriges huvudstad?", "Stockholm");
questControll.setQuestion(quest.getCategory(), quest.getQuestion(), quest.getAnswear());
Parent root1 = (Parent) fxmlQuestLoader.load();
root1.setId("pane");
Stage app_stage = (Stage)((Node) event.getSource()).getScene().getWindow();
Scene root1_scene = new Scene(root1);
root1_scene.getStylesheets().addAll(this.getClass().getResource("style.css").toExternalForm());
app_stage.hide();
app_stage.setScene(root1_scene);
app_stage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
third controller
public class FXMLQuestionDocumentController implements Initializable {
private FXMLCategoriesDocumentController catControll;
private Question quest;
#FXML
public Label category = new Label();
#FXML
public TextField question = new TextField();
#FXML
public TextField answear = new TextField();
/**
* Initializes the controller class.
*/
#Override
public void initialize(URL url, ResourceBundle rb) {
}
public void setQuestion(String cat, String quest, String ans){
if(category.getText() == null || question.getText() == null || answear.getText() == null){
System.out.println("everything is null");
}else{
category.setText(cat);
question.setText(quest);
answear.setText(ans);
}
}
Question class
public class Question {
private String category;
private String question;
private String answear;
public Question(String cat, String quest, String ans){
this.category = cat;
this.question = quest;
this.answear = ans;
}
public void setCategory(String cat){
this.category = cat;
}
public void setQuestion(String quest){
this.question = quest;
}
public void setAnswear(String ans){
this.answear = ans;
}
public String getCategory(){
return category;
}
public String getQuestion(){
return question;
}
public String getAnswear(){
return answear;
}
}
FXML second controller(category)
category xml
FXML third controller(question)
question xml

You can specify the the class of controller in each XML-File by using the fx:controller-Tag (here) in the highest element of your (f)xml-Tree.
You can load it then by using this:
YourCustomController controller;
//some code...
try {
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("FXMLQuestionDocument.fxml"));
controller = loader.<YourCustomController>getController();
//assume that we create a question here
Question q = new Question(...);
controller.setQuestion(q);
}
//further code...
Edit after comments:
As fabian said, attributes annotated with #FXML are created before the initialize()-method if the fx:id-tag is set for an element in your FXML-file. The fx:id-tag must be the same as the attribute in your controller.
In you fxml-file (for example a Label):
<Label fx:id="question" ...>
....
</Label>
In your Controller-class:
public class YourCustomController implements Initializable {
#FXML Label question;
//...
public void initialize() {
//...
}
public void setQuestion(Question q) {
question.setText(q.getQuestion();
}
}
For further information, see the link in jewelseas comment.
I tried this tomorrow and I hope I transferred it here the right way.
Edit from July, 13th
In your FXMLQuestionDocumentController, you don't need to initiliaze your controls. See:
public class FXMLQuestionDocumentController implements Initializable {
private FXMLCategoriesDocumentController catControll;
private Question quest;
#FXML
public Label category;
#FXML
public TextField question;
#FXML
public TextField answear;
}
Also, initialize your controller after you initialized your Pane.
`#FXML
private void geografButtonAction(ActionEvent event) {
try {
FXMLLoader fxmlQuestLoader = new FXMLLoader(getClass().getResource("FXMLQuestionDocument.fxml"));
quest = new Question("Geografi", "Vad heter Sveriges huvudstad?", "Stockholm");
Parent root1 = (Parent) fxmlQuestLoader.load();
root1.setId("pane");
this.questControll = fxmlQuestLoader.FXMLQuestionDocumentController>getController();
questControll.setQuestion(quest.getCategory(), quest.getQuestion(), quest.getAnswear());
Stage app_stage = (Stage)((Node) event.getSource()).getScene().getWindow();
Scene root1_scene = new Scene(root1);
root1_scene.getStylesheets().addAll(this.getClass().getResource("style.css").toExternalForm());
app_stage.hide();
app_stage.setScene(root1_scene);
app_stage.show();
} catch(Exception e) {
e.printStackTrace();
}
}`

How to run two methods in sequence with the same button in javafx?

I'm trying to fill a listview with the artist and title of songs using the open() method.
To achieve this I created the artist and title ArrayLists and merged them using the create() method.
The problem is, when I try to run create() inside open() nothing happens. However, if I assign the create() method to a different button and click it after using the filechooser everything works fine.
So, I would like to know if it is possible to run the create() method after the open() method using only one button via fxml or regular java code.
public class PLController implements Initializable {
#Override
public void initialize(URL location, ResourceBundle resources) {
list.setItems(visibleList);
}
List<File> filelist = new ArrayList<File>();
ArrayList<String> title = new ArrayList<String>();
ArrayList<String> artist = new ArrayList<String>();
ObservableList<String> visibleList = FXCollections.observableArrayList();
#FXML
ListView<String> list;
#FXML
Button impButton;
public void create(){
for(int i = 0; i < title.size(); i++){
visibleList.add(artist.get(i) +" - " +title.get(i));
Collections.sort(visibleList);
}
}
public void handleMetadata(String key, Object value){
if (key.equals("title")){
title.add(value.toString());
}
if (key.equals("artist")){
artist.add(value.toString());
}
}
public void open(){
FileChooser chooser = new FileChooser();
filelist = chooser.showOpenMultipleDialog(impButton.getScene().getWindow());
for(File f:filelist){
try {
Media media = new Media(f.toURI().toURL().toString());
media.getMetadata().addListener(new MapChangeListener<String, Object>(){
#Override
public void onChanged(Change<? extends String, ? extends Object> change) {
if(change.wasAdded()) {
handleMetadata(change.getKey(), change.getValueAdded());
}
}
});
} catch (MalformedURLException e) {
e.printStackTrace();
}
}create(); //Nothing happens
}

As others have pointed out, the Media object does not have its metadata initialized immediately. (It needs to read data from the URL and populate those metadata as it receives them.) That is why the metadata are exposed as an ObservableMap. When you reach the end of your open() method, it is highly unlikely that the metadata will have been initialized, so your create() method will not see any data at that point.
What you need to do is observe the map, and update the ListView once both the artist and title are available. The best way to do this, in my opinion, is to encapsulate the information you want into a separate class:
public class Video {
private final Media media ;
private final ReadOnlyStringWrapper artist = new ReadOnlyStringWrapper("Unknown");
private final ReadOnlyStringWrapper title = new ReadOnlyStringWrapper("Title");
public Video(File file) {
try {
this.media = new Media(file.toURI().toURL().toExternalForm());
artist.bind(Bindings.createStringBinding(() -> {
Object a = media.getMetadata().get("artist");
return a == null ? "Unknown" : a.toString();
}, media.getMetadata()));
title.bind(Bindings.createStringBinding(() -> {
Object t = media.getMetadata().get("title");
return t == null ? "Unknown" : t.toString();
}, media.getMetadata()));
}
catch (Exception e) {
throw new RuntimeException("Could not create Video for "+file, e);
}
}
public ReadOnlyStringProperty titleProperty() {
return title.getReadOnlyProperty();
}
public ReadOnlyStringProperty artistProperty() {
return artist.getReadOnlyProperty();
}
public final String getTitle() {
return title.get();
}
public final String getArtist() {
return artist.get();
}
public final Media getMedia() {
return media ;
}
}
Now you can create a ListView<Video> to display the videos. Use a cell factory to display the artist and the title in the format you want. You can make sure that the observable list fires updates when either the artist or title properties change, and you can keep it sorted via a SortedList.
#FXML
private ListView<Video> list ;
private ObservableList<Video> visibleList ;
public void initialize() {
visibleList = FXCollections.observableArrayList(
// make list fire updates when artist or title change:
v -> new Observable[] {v.artistProperty(), v.titleProperty()});
list.setItems(new SortedList<>(list, Comparator.comparing(this::formatVideo)));
list.setCellFactory(lv -> new ListCell<Video>() {
#Override
public void updateItem(Video item, boolean empty) {
super.updateItem(item, empty) ;
setText(formatVideo(item));
}
});
}
#FXML
private void open() {
FileChooser chooser = new FileChooser();
List<File> fileList = chooser.showOpenMultipleDialog(impButton.getScene().getWindow());
if (fileList != null) {
fileList.stream()
.map(Video::new)
.forEach(visibleList::add);
}
}
private String formatVideo(Video v) {
if (v == null) return "" ;
return String.format("%s - %s", v.getArtist(), v.getTitle());
}

Simply creating a Media object and assigning a listener to it won't fire the code in the listener. So the title list in your code remains empty. The create() method is called, but since you are iterating over an empty list, nothing actually happens.
Use a debugger or add some logging information in such cases.
Also, you should sort the list after the for loop, not every time you add an item.

Refreshing an FXML Table on button Press

How do you refresh the data in your tableView on button Press using FXML?
I have the following file structure and I want to refresh the data in this table when a button is pressed. Would anyone know a solution?
public class MyTable {
private final SimpleStringProperty ID = new SimpleStringProperty("");
private final SimpleStringProperty ParticipantID = new SimpleStringProperty("");
public Positions() {
this("", "")
}
public Positions(String ID, String ParticipantID) {
setMemberID(ID);
setParticipantID(ParticipantID);
}
public String getParticipantID() {
return ParticipantID.get();
}
public void setParticipantID(String pID) {
ParticipantID.set(ParticipantID);
}
public String getID() {
return ID.get();
}
public void ID(String cID) {
ID.set(ID);
}
}
I initialise this table on the tablecontroller file for this. Now on button press I would like the tableview which is an FXML file update itself. How do I do this?

Thanks but the solution to this was to have one global ObservableList<> data which you then modify on a button press action event. What I was trying to do was create another observable list which does not work.

If you want to update only on button press and not as data is modified that is the default way ?
The simplest way to do would be to create a bean to which all data is updated and the make the button synchronize it with the bean that represents a row in your table.
public class TableBean
{
MyTable child;
String Id;
String ParticipantId;
public void Sync()
{
child.Id(Id);
child.setParticipantID(ParticipantId);
}
}
It is important to note that your methods
violate JavaFX convetion , this probably brakes things. An example of 3 methods used for every propery in JavaFX.
private final IntegerProperty ratio = new SimpleIntegerProperty();
public int getRatio() {
return ratio.get();
}
public void setRatio(int value) {
ratio.set(value);
}
public IntegerProperty ratioProperty() {
return ratio;
}