Java: Printing program output to a physical printer

Question

I am a relatively new programmer so this may be a really simple question to answer but its got me a bit stumped..

I'm trying to print my Java GUI's final output to a printer. Now, in my GUI, I have it so that when you hit print, a pop-up comes up with the list of available printers, and based on the one you select, it should print to that printer.

However it is not. I got most of my code by scouring the internet for solutions to this problem and found some promising code. However, it printed off of a File. So all I simply do in my method is write my output to a file first so that I can use the same methodology.

A couple things before the method:

1. There are no errors or exceptions thrown.

2. The File I attempt to create every time always exists, and with the correct text.

3. The printer I am printing to IS receiving the print job, it even thinks it has completed it.

If I had to guess, I would think I am perhaps writing the output to File in way that the Printer will not except but isn't telling me. Anyways, there is quite a bit in this code that I don't really have a firm understanding of so please let me know what you can find.

Here is my code:

private void printToPrinter()
    {

        File output = new File("PrintFile.txt");
        output.setWritable(true);
        //Will become the user-selected printer.
        Object selection = null;
        try 
        {
            BufferedWriter out = new BufferedWriter(new FileWriter(output));
            out.write(calculationTextArea.getText() + "\n" + specificTextArea.getText());
            out.close();

        }
        catch (java.io.IOException e)
        {
            System.out.println("Unable to write Output to disk, error occured in saveToFile() Method.");
        }
        FileInputStream textStream = null;
        try 
        {
            textStream = new FileInputStream("PrintFile.txt");
        }
        catch (java.io.FileNotFoundException e)
        {
            System.out.println("Error trying to find the print file created in the printToPrinter() method");
        }

        DocFlavor flavor = DocFlavor.INPUT_STREAM.AUTOSENSE;
        Doc mydoc = new SimpleDoc(textStream, flavor, null);

        //Look up available printers.
        PrintService[] printers = PrintServiceLookup.lookupPrintServices(flavor, null);

        if (printers.length == 0)
        {
            // No printers found. Inform user.
            jOptionPane2.showMessageDialog(this, "No printers could be found on your system!", "Error!", JOptionPane.ERROR_MESSAGE);
        }
        else
        {
            selection = jOptionPane2.showInputDialog(this, "Please select the desired printer:", "Print", 
                                                        JOptionPane.INFORMATION_MESSAGE, null, printers,
                                                        PrintServiceLookup.lookupDefaultPrintService()); 
            if (selection instanceof PrintService)
            {
                PrintService chosenPrinter = (PrintService) selection;
                DocPrintJob printJob = chosenPrinter.createPrintJob();
                try 
                {
                    printJob.print(mydoc, null);
                }
                catch (javax.print.PrintException e) 
                {
                    jOptionPane2.showMessageDialog(this, "Unknown error occured while attempting to print.", "Error!", JOptionPane.ERROR_MESSAGE);
                }
            }
        }
}

Solution 1

So I found a way that works perfectly for my situation and I thought I would just post what it was in case it would be useful to anyone.

The basics of the solution are that Java does have its own full fledged (At least compared to mine) printDialog popUp that has more than I needed (Page layout editing, previews, etc) and all you have to do to use it is hand it an object that implements Printable and it is within that object that you create a graphic and draw your document.

I just needed to draw my output String and that was easily done, I even found a StringReader so I can stop naively Writing a File just to get my output in a BufferedReader.

Here's the code. There are two parts, the method and the class where I draw the image:

Method:

private void printToPrinter()
{
    String printData = CalculationTextArea.getText() + "\n" + SpecificTextArea.getText();
    PrinterJob job = PrinterJob.getPrinterJob();
    job.setPrintable(new OutputPrinter(printData));
    boolean doPrint = job.printDialog();
    if (doPrint)
    { 
        try 
        {
            job.print();
        }
        catch (PrinterException e)
        {
            // Print job did not complete.
        }
    }
}

And here is the Class where the document is printed:

public class OutputPrinter implements Printable 
{
    private String printData;

    public OutputPrinter(String printDataIn)
    {
    this.printData = printDataIn;
    }

@Override
public int print(Graphics g, PageFormat pf, int page) throws PrinterException
{
    // Should only have one page, and page # is zero-based.
    if (page > 0)
    {
        return NO_SUCH_PAGE;
    }

    // Adding the "Imageable" to the x and y puts the margins on the page.
    // To make it safe for printing.
    Graphics2D g2d = (Graphics2D)g;
    int x = (int) pf.getImageableX();
    int y = (int) pf.getImageableY();        
    g2d.translate(x, y); 

    // Calculate the line height
    Font font = new Font("Serif", Font.PLAIN, 10);
    FontMetrics metrics = g.getFontMetrics(font);
    int lineHeight = metrics.getHeight();

    BufferedReader br = new BufferedReader(new StringReader(printData));

    // Draw the page:
    try
    {
        String line;
        // Just a safety net in case no margin was added.
        x += 50;
        y += 50;
        while ((line = br.readLine()) != null)
        {
            y += lineHeight;
            g2d.drawString(line, x, y);
        }
    }
    catch (IOException e)
    {
        // 
    }

    return PAGE_EXISTS;
}
}

Anyways that is how I solved this problem! Hope it can be of some use to someone!

Solution 2

Create a JTextComponent (I suggest a JTextArea so you can use append()), and append what you need to the field. Do not display it on the view, it is simply a hidden field for printing purposes.

All JTextComponents have a print() method. Simply call hiddenTextArea.print() and the rest is handled for you.

        JTextArea hiddenTextArea = new JTextArea();
        for (String s : dataToPrintCollection) {
            hiddenTextArea.append(s + "\n");
        }

        try {
            hiddenTextArea.print();
        } catch (PrinterException e) {}

Comments

[Alex]

Thanks for the answer! That could work, but I'm pulling from two separate JTextAreas on two different tabs. The thing is I know that they will always be able to fit on one page so I would rather pull the text from both of them and print it on one page for user simplicity.

[Anthea]

tried to find a solution but somehow its not possible to paint a graphics onto another.

[ivstas]

There is probably flaw in your code. At the beginning, you translate the coordinate system origin to the start of imageable area (g2d.translate(x, y)). After that you can draw any objects with coordinates relevant to this origin. However, you keep imageable area x/y coordinates to use it later (which is senseless since you already translated the origin to these coordinates)

[ivstas]

The possible solution might be either removing invocation of g2d.translate(x, y); or changing x+=50; y+=50; to x=50;y=50;