当我在EDT以外的线程上调用我的打印方法时，什么都没发生？

Question

I have a method that does some printing and I want the task to run on another thread (not on the EDT) because it might be creating a large file and I dont want the long process to freeze the GUI. The execution works perfectly on the EDT (with GUI freezing of course - which isn't desired), but when invoked on a different thread, it just doesn't execute.
Here goes the method;

                    buildReceipt(itemList, method);

Where;

• itemList is an ArrayList used to populate the receipt, and
• method is an enum Type that determines whether to make the output a .pdf File or Send it directly to a Printer

The code above produces the document nicely when executed on the EDT but when I tried making it a background task using doInBackground() method of SwingWorker , it just didn't do anything at all; Then I got curious and tried the following;

Thread thread = new Thread(new Runnable(){
    @Override
    public void run()
    {
        buildReceipt(itemList, method);
    }
});
thread.start();

and still, nothing happened......... More funny and confusing is the fact that I have even tried SwingUtilities.InvokeLater & SwingUtilities.InvokeAndWait (which by documentation run on the EDT) but still to no avail.

I have searched as many Stack Overflow related questions as I could, but none addresses my strange problem. I really need help on this one. Been stuck since yesteray?!?!?!

EDIT:

In Respose to Jean Waghetti; here's briefly what happens inside buildReceipt

 private boolean buildReceipt(ArrayList<Sales> itemList, PrintMethod method) { boolean built = false; if(!itemList.isEmpty()) { InvoiceDesign design = new InvoiceDesign(itemList); try { JasperReportBuilder report = design.build(); if(method.equals(PrintMethod.PDF)) { appManager.connectToDB(); File fileDir = appManager.getReceiptsDir(); appManager.disconnectDB(); FileOutputStream fos = new FileOutputStream(fileDir); report.toPdf(fos); fos.close(); built = true; } else if(method.equals(PrintMethod.PRINTER)) { report.print(true); built = true; } } catch(IOException e) { e.printStackTrace(); } catch (DRException e) { e.printStackTrace(); } } return built; } 

Answer 1

因此，基本上您的项目列表为空，因此它永远不会在该方法的IF条件下执行代码。