Question

I have a method in my SWT class that gets the selected value from my table. The value is actually the file name of the object.

 public String getPDFFileName() { 
    int row = viewer.getTable().getSelectionIndex();
    if (row != -1) {
       return pdfFileName = AplotSaveDataModel.getInstance().getSelectedPDFFileName(row);
    }
    else {
       MessageDialog.openError(null, "PDF Selection Error Message", "You need to select a PDF to view.");
    }
    return null;
  }

I have a composite in the same class that is bridging SWT and Swing. This method takes the String Filename and creates a Swing Viewer displaying the file.

 protected Control createPDFButtons(Composite parent) {
  final Composite swtAwtComponent = new Composite(parent, SWT.EMBEDDED);
  GridData mainLayoutData = new GridData(SWT.FILL, SWT.CENTER, true, false); 
  mainLayoutData.horizontalSpan = 1; 
  swtAwtComponent.setLayoutData(mainLayoutData); 
  GridLayout mainLayout = new GridLayout(1, false); 
  mainLayout.marginWidth = 0; 
  mainLayout.marginHeight = 0; 
  swtAwtComponent.setLayout(mainLayout); 
  final Frame frame = SWT_AWT.new_Frame(swtAwtComponent);
  final JPanel panel = new JPanel();
  panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS)); 

  JButton viewerButton = new JButton("View Selected PDF");
  viewerButton.addActionListener(new ActionListener(){
     public void actionPerformed(ActionEvent actionevent) {

        final File viewerFile = new File(getPDFFileName());
        final AplotPdfViewer pdfv = new AplotPdfViewer(true);
        try {
           pdfv.openFile(viewerFile);
        }
        catch (IOException e) {
           e.printStackTrace();
        }

     }
  });

  panel.add(viewerButton);
  frame.add(panel);
  return swtAwtComponent;
}      

If I try and run the getPDFFileName() in the composite, I get a SWT thread error. I understand where that comes from.

I am not sure how to get the value from getPDFFileName() and use it in final File viewerFile = new File(“NEED FILENAME OF SELECTION”);

Answer 1

You need to be a UI Thread when you try to access a widget (in your case the Table). You can do it using Display.syncExec

  JButton viewerButton = new JButton("View Selected PDF");
  viewerButton.addActionListener(new ActionListener(){
     public void actionPerformed(ActionEvent actionevent) {
        // Retrieve the pdf file name in the UI thread
        final String[] filename = new String[1];
        Display.getCurrent().syncExec(new Runnable() { 
            public void run() {
                filename[0] = getPDFFileName();
            }
        }

        final File viewerFile = new File(filename[0]);
        final AplotPdfViewer pdfv = new AplotPdfViewer(true);
        try {
           pdfv.openFile(viewerFile);
        }
        catch (IOException e) {
           e.printStackTrace();
        }    
     }
  });

Consider to put the call to syncExec directly in the getPDFFileName method if it’s needed several times. The String result is saved in an array because you can’t return a result with syncExec.