JavaFX ClassCastException using iText PDF

Question

I am trying to download a TableView in JavaFx as an pdf document. I am using iText 7.2.5 . When I am clicking the button to download the TableView, it is asking me to select the folder then it is asking to write the name for the pdf document then after it; when I press ok to download the document, it downloads the pdf file that is unable to show any content even a blank page. When I open the pdf file with chrome it shows this, and I also tried to open with Adobe Acrobat, but situation is the same with pdf file.

Error Failed to load PDF document.

First, it was giving an exception for slf4j; then I added these jar files in classpath: slf4j-simple-2.0.6.jar , slf4j-api-2.0.6-javadoc.jar , slf4j-api-2.0.6.jar . It was giving warning for provider not found or something like that; that was solved after adding slf4j-simple-2.0.6.jar.

I saw a similar question here java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory problem.

Answer of this question is: It turns out that it missed the following 3 jars : slf4j.api, slf4j-log4j12, and log4j

It works now after adding the above 3 jars.

These are all the files at org/slf4j integration/ - -
jcl-over-slf4j/ - -
jcl104-over-slf4j/ - -
jul-to-slf4j/ - -
log4j-over-slf4j/ - -
nlog4j/ - -
osgi-over-slf4j/ - -
slf4j-android/ - -
slf4j-api/ - -
slf4j-archetype/ - -
slf4j-converter/ - -
slf4j-ext/ - -
slf4j-jcl/ - -
slf4j-jdk-platform-logging/ - -
slf4j-jdk14/ - -
slf4j-log4j12/ - -
slf4j-log4j13/ - -
slf4j-migrator/ - -
slf4j-nop/ - -
slf4j-parent/ - -
slf4j-reload4j/ - -
slf4j-simple/ - -
slf4j-site/ - -
slf4j-skin/ - -
taglib/ - -

log4j-over-slf4j/ ---> is it the file log4j that is mentioned in reference answer to the question.

I am unable to get slf4j-log4j12.

because org/slf4j/slf4j-log4j12/2.0.6 contains no jar file but this

slf4j-log4j12-2.0.6.pom 2022-12-12 19:14 873
slf4j-log4j12-2.0.6.pom.asc 2022-12-12 19:14 317
slf4j-log4j12-2.0.6.pom.md5 2022-12-12 19:14 32
slf4j-log4j12-2.0.6.pom.sha1

Here is the code on download button:

@FXML
public void ButtonDownload(ActionEvent event) {
     
    DirectoryChooser directoryChooser = new DirectoryChooser();
    File selectedDirectory =                directoryChooser.showDialog(TableName.getScene().getWindow());
    if (selectedDirectory == null) {
        return;
    }
    
    
    TextInputDialog dialog = new TextInputDialog("table");
    dialog.setTitle("Enter File Name");
    dialog.setHeaderText("Enter the name for the PDF file:");
    dialog.setContentText("File name:");
    Optional<String> result = dialog.showAndWait();
    
    if (result.isPresent()) {
        try {
            String fileName = result.get();
            if (!fileName.endsWith(".pdf")) {
                fileName = fileName + ".pdf";
            }
            String filePath = selectedDirectory.getAbsolutePath() + "/" + fileName;
            OutputStream file = new FileOutputStream(filePath);
            PdfDocument pdfDoc = new PdfDocument(new PdfWriter(filePath));
            Document document = new Document(pdfDoc);
            Table pdfTable = new Table(TableName.getColumns().size());
            
            
            for (TableColumn<?, ?> column : TableName.getColumns()) {
                pdfTable.addCell(column.getText());
            }
            
            for (Object item : TableName.getItems()) {
                
                for (TableColumn<?, ?> column : TableName.getColumns()) {
                /*this line is line:254*/
                    pdfTable.addCell(column.getCellData((int) item).toString());
                    
                }
            }
            document.add(pdfTable);
            document.close();
        } catch (Exception e) {
            System.out.println("Exception while downloading pdf tableView: "+e);
            e.printStackTrace();
        }
    }
}

This is the StackTrace:

Exception while downloading pdf tableView: java.lang.ClassCastException: class application.(className --> that is the controller of the fxml file where the download button is placed) cannot be cast to class java.lang.Integer (application.className(Controller) is in unnamed module of loader 'app'; java.lang.Integer is in module java.base of loader 'bootstrap')
java.lang.ClassCastException: class application.className(Controller) cannot be cast to class java.lang.Integer (application.className(Controller) is in unnamed module of loader 'app'; java.lang.Integer is in module java.base of loader 'bootstrap')
    at application.className(Controller).DownloadMethod(className(Controller).java:254)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:77)
    at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at javafx.base@19.0.2.1/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml@19.0.2.1/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:84)
    at javafx.fxml@19.0.2.1/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1852)
    at javafx.fxml@19.0.2.1/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1724)
    at javafx.base@19.0.2.1/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base@19.0.2.1/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base@19.0.2.1/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19.0.2.1/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19.0.2.1/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.base@19.0.2.1/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics@19.0.2.1/javafx.scene.Node.fireEvent(Node.java:8923)
    at javafx.controls@19.0.2.1/javafx.scene.control.Button.fire(Button.java:203)
    at javafx.controls@19.0.2.1/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:207)
    at javafx.controls@19.0.2.1/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
    at javafx.base@19.0.2.1/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:247)
    at javafx.base@19.0.2.1/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base@19.0.2.1/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base@19.0.2.1/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19.0.2.1/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19.0.2.1/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base@19.0.2.1/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.base@19.0.2.1/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics@19.0.2.1/javafx.scene.Scene$MouseHandler.process(Scene.java:3894)
    at javafx.graphics@19.0.2.1/javafx.scene.Scene.processMouseEvent(Scene.java:1887)
    at javafx.graphics@19.0.2.1/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2620)
    at javafx.graphics@19.0.2.1/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:411)
    at javafx.graphics@19.0.2.1/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:301)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at javafx.graphics@19.0.2.1/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:450)
    at javafx.graphics@19.0.2.1/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:424)
    at javafx.graphics@19.0.2.1/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:449)
    at javafx.graphics@19.0.2.1/com.sun.glass.ui.View.handleMouseEvent(View.java:551)
    at javafx.graphics@19.0.2.1/com.sun.glass.ui.View.notifyMouse(View.java:937)
    at javafx.graphics@19.0.2.1/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics@19.0.2.1/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
    at java.base/java.lang.Thread.run(Thread.java:833)

EDIT: 254 original code

 pdfTable.addCell(column.getCellData(item).toString());

but then It asked to cast argument item to int like this

 pdfTable.addCell(column.getCellData((int) item).toString());

Kindly help out to solve this.

Answer 1

Exception while downloading pdf tableView: java.lang.ClassCastException: class application.(className --> that is the controller of the fxml file where the download button is placed) cannot be cast to class java.lang.Integer (application.className(Controller) is in unnamed module of loader 'app'; java.lang.Integer is in module java.base of loader 'bootstrap')
java.lang.ClassCastException: class application.className(Controller) cannot be cast to class java.lang.Integer (application.className(Controller) is in unnamed module of loader 'app'; java.lang.Integer is in module java.base of loader 'bootstrap')
    at application.className(Controller).DownloadMethod(className(Controller).java:254)

As this stack trace suggests, the error occurs because you are trying to cast the table item, which apparently is not an integer, to an integer at line number 254. Note that the method TableView#getItems returns an iterable object of type ObservableList<S>.

You need to fix the following line at the minimum: pdfTable.addCell(column.getCellData((int) item).toString());

It looks like you intend to add the index of the item in the table view rather than the item itself to your pdf table. Try this instead:

pdfTable.addCell(column.getCellData(TableName.getItems().indexOf(item)).toString());

Answer 2

Thanks to all! Special Thanks to @James_D

This is the code that is printing the pdf correctly.

@FXML
 public void DownloadButtonMethod(ActionEvent event) {
     
        DirectoryChooser directoryChooser = new DirectoryChooser();
        File selectedDirectory = directoryChooser.showDialog(TableName.getScene().getWindow());
        if (selectedDirectory == null) {
            return;
        }
        
        
        TextInputDialog dialog = new TextInputDialog("table");
        dialog.setTitle("Enter File Name");
        dialog.setHeaderText("Enter the name for the PDF file:");
        dialog.setContentText("File name:");
        Optional<String> result = dialog.showAndWait();
        
        if (result.isPresent()) {
            try {
                String fileName = result.get();
                if (!fileName.endsWith(".pdf")) {
                    fileName = fileName + ".pdf";
                }
                String filePath = selectedDirectory.getAbsolutePath() + "/" + fileName;
                OutputStream file = new FileOutputStream(filePath);
                PdfDocument pdfDoc = new PdfDocument(new PdfWriter(filePath));
                Document document = new Document(pdfDoc);
                Table pdfTable = new Table(TableName.getColumns().size());
                
                try {
                    
                for (TableColumn<ClassName(holds records), ?> column : TableName.getColumns()) {
                    pdfTable.addCell(column.getText());
                }
                
                }catch(Exception e) {
                    System.out.println("E1: "+e);
                    e.printStackTrace();
                }
                
                
                try {
                    
                    for (int i = 0; i < TableName.getItems().size(); i++) {
                        for (TableColumn<ClassName(holds records), ?> column : TableName.getColumns()) {
                            try {
                                pdfTable.addCell(column.getCellData(i).toString());
                            } catch (NullPointerException e) {
                                pdfTable.addCell("");
                            }
                        }
                    }
                    
                } catch(Exception e) {
                    System.out.println("E2: "+e);
                    e.printStackTrace();
                }
    
                document.add(pdfTable);
                document.close();
            } catch (Exception e) {
                System.out.println("Exception while downloading pdf tableView: "+e);
                e.printStackTrace();
            }
        }
    }

We have handled the NullPointerException by checking if the object is null, if yes then we have added the empty string to it so it couldn't throw a NullPointerException. And the ClassCastException was caused because when I was trying to cast an object to a type that it is not compatible with. Then I placed className(contains records: i.e variables, constructor, and getters and setters) as a type instead of using wildcards in TabelColumn as suggested by @James_D.

Thanks Again :)