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How to print multiple header lines with MessageFormat using a JTable

Posted by: admin December 28, 2021 Leave a comment

Questions:

I have a table called table and its filled with data, I also have a MessageFormat header I want to use as a header to print the JTable this is the MessageFormat:

MessageFormat header = new  MessageFormat("Product: "
                    + task.getProductName() + "  Job: "
                    + task.getJobNumber() + "  Task: " + task.getTaskID()
                    );

I want to print 3 lines in the header, one for Product, Job and Task

the way I print this table is like so:

table.print(JTable.PrintMode.FIT_WIDTH, header, null);

I can’t seem to figure out how to print the header in 3 seperate lines, I tried using the \n to make a new line but that doesn’t seem to work.

Answers:

It’s gonna be long answer (code wise) because the only solution I found was to implement a custom Printable. Of course I didn’t write the following code myself, I mostly copied the code I extracted from the jdk sources and made some adjustments.

Here we are:

This is the way you said you invoke the print method:

DefaultTableModel dtm = new DefaultTableModel(new String[] { "Column 1" }, 1);

JTable table = new JTable(dtm) {
@Override
    public Printable getPrintable(PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat) {
       return new TablePrintable(this, printMode, headerFormat, footerFormat);
    }
};

where TablePrintable is the following class (sorry for not being concise here):

static class TablePrintable implements Printable {
private final JTable table;
private final JTableHeader header;
private final TableColumnModel colModel;
private final int totalColWidth;
private final JTable.PrintMode printMode;
private final MessageFormat headerFormat;
private final MessageFormat footerFormat;
private int last = -1;
private int row = 0;
private int col = 0;
private final Rectangle clip = new Rectangle(0, 0, 0, 0);
private final Rectangle hclip = new Rectangle(0, 0, 0, 0);
private final Rectangle tempRect = new Rectangle(0, 0, 0, 0);
private static final int H_F_SPACE = 8;
private static final float HEADER_FONT_SIZE = 18.0f;
private static final float FOOTER_FONT_SIZE = 12.0f;
private final Font headerFont;
private final Font footerFont;
public TablePrintable(JTable table, JTable.PrintMode printMode, MessageFormat headerFormat,
MessageFormat footerFormat) {
this.table = table;
header = table.getTableHeader();
colModel = table.getColumnModel();
totalColWidth = colModel.getTotalColumnWidth();
if (header != null) {
// the header clip height can be set once since it's unchanging
hclip.height = header.getHeight();
}
this.printMode = printMode;
this.headerFormat = headerFormat;
this.footerFormat = footerFormat;
// derive the header and footer font from the table's font
headerFont = table.getFont().deriveFont(Font.BOLD, HEADER_FONT_SIZE);
footerFont = table.getFont().deriveFont(Font.PLAIN, FOOTER_FONT_SIZE);
}
@Override
public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
// for easy access to these values
final int imgWidth = (int) pageFormat.getImageableWidth();
final int imgHeight = (int) pageFormat.getImageableHeight();
if (imgWidth <= 0) {
throw new PrinterException("Width of printable area is too small.");
}
// to pass the page number when formatting the header and footer
// text
Object[] pageNumber = new Object[] { Integer.valueOf(pageIndex + 1) };
// fetch the formatted header text, if any
String headerText = null;
if (headerFormat != null) {
headerText = headerFormat.format(pageNumber);
}
// fetch the formatted footer text, if any
String footerText = null;
if (footerFormat != null) {
footerText = footerFormat.format(pageNumber);
}
// to store the bounds of the header and footer text
Rectangle2D hRect = null;
Rectangle2D fRect = null;
// the amount of vertical space needed for the header and footer
// text
int headerTextSpace = 0;
int footerTextSpace = 0;
// the amount of vertical space available for printing the table
int availableSpace = imgHeight;
// if there's header text, find out how much space is needed for it
// and subtract that from the available space
if (headerText != null) {
graphics.setFont(headerFont);
int nbLines = headerText.split("\n").length;
hRect = graphics.getFontMetrics().getStringBounds(headerText, graphics);
hRect = new Rectangle2D.Double(hRect.getX(), Math.abs(hRect.getY()), hRect.getWidth(),
hRect.getHeight() * nbLines);
headerTextSpace = (int) Math.ceil(hRect.getHeight() * nbLines);
availableSpace -= headerTextSpace + H_F_SPACE;
}
// if there's footer text, find out how much space is needed for it
// and subtract that from the available space
if (footerText != null) {
graphics.setFont(footerFont);
fRect = graphics.getFontMetrics().getStringBounds(footerText, graphics);
footerTextSpace = (int) Math.ceil(fRect.getHeight());
availableSpace -= footerTextSpace + H_F_SPACE;
}
if (availableSpace <= 0) {
throw new PrinterException("Height of printable area is too small.");
}
// depending on the print mode, we may need a scale factor to
// fit the table's entire width on the page
double sf = 1.0D;
if (printMode == JTable.PrintMode.FIT_WIDTH && totalColWidth > imgWidth) {
// if not, we would have thrown an acception previously
assert imgWidth > 0;
// it must be, according to the if-condition, since imgWidth > 0
assert totalColWidth > 1;
sf = (double) imgWidth / (double) totalColWidth;
}
// dictated by the previous two assertions
assert sf > 0;
// This is in a loop for two reasons:
// First, it allows us to catch up in case we're called starting
// with a non-zero pageIndex. Second, we know that we can be called
// for the same page multiple times. The condition of this while
// loop acts as a check, ensuring that we don't attempt to do the
// calculations again when we are called subsequent times for the
// same page.
while (last < pageIndex) {
// if we are finished all columns in all rows
if (row >= table.getRowCount() && col == 0) {
return NO_SUCH_PAGE;
}
// rather than multiplying every row and column by the scale
// factor
// in findNextClip, just pass a width and height that have
// already
// been divided by it
int scaledWidth = (int) (imgWidth / sf);
int scaledHeight = (int) ((availableSpace - hclip.height) / sf);
// calculate the area of the table to be printed for this page
findNextClip(scaledWidth, scaledHeight);
last++;
}
// create a copy of the graphics so we don't affect the one given to
// us
Graphics2D g2d = (Graphics2D) graphics.create();
// translate into the co-ordinate system of the pageFormat
g2d.translate(pageFormat.getImageableX(), pageFormat.getImageableY());
// to save and store the transform
AffineTransform oldTrans;
// if there's footer text, print it at the bottom of the imageable
// area
if (footerText != null) {
oldTrans = g2d.getTransform();
g2d.translate(0, imgHeight - footerTextSpace);
String[] lines = footerText.split("\n");
printText(g2d, lines, fRect, footerFont, imgWidth);
g2d.setTransform(oldTrans);
}
// if there's header text, print it at the top of the imageable area
// and then translate downwards
if (headerText != null) {
String[] lines = headerText.split("\n");
printText(g2d, lines, hRect, headerFont, imgWidth);
g2d.translate(0, headerTextSpace + H_F_SPACE);
}
// constrain the table output to the available space
tempRect.x = 0;
tempRect.y = 0;
tempRect.width = imgWidth;
tempRect.height = availableSpace;
g2d.clip(tempRect);
// if we have a scale factor, scale the graphics object to fit
// the entire width
if (sf != 1.0D) {
g2d.scale(sf, sf);
// otherwise, ensure that the current portion of the table is
// centered horizontally
} else {
int diff = (imgWidth - clip.width) / 2;
g2d.translate(diff, 0);
}
// store the old transform and clip for later restoration
oldTrans = g2d.getTransform();
Shape oldClip = g2d.getClip();
// if there's a table header, print the current section and
// then translate downwards
if (header != null) {
hclip.x = clip.x;
hclip.width = clip.width;
g2d.translate(-hclip.x, 0);
g2d.clip(hclip);
header.print(g2d);
// restore the original transform and clip
g2d.setTransform(oldTrans);
g2d.setClip(oldClip);
// translate downwards
g2d.translate(0, hclip.height);
}
// print the current section of the table
g2d.translate(-clip.x, -clip.y);
g2d.clip(clip);
table.print(g2d);
// restore the original transform and clip
g2d.setTransform(oldTrans);
g2d.setClip(oldClip);
// draw a box around the table
g2d.setColor(Color.BLACK);
g2d.drawRect(0, 0, clip.width, hclip.height + clip.height);
// dispose the graphics copy
g2d.dispose();
return PAGE_EXISTS;
}
private void printText(Graphics2D g2d, String[] lines, Rectangle2D rect, Font font, int imgWidth) {
g2d.setColor(Color.BLACK);
g2d.setFont(font);
for (int i = 0; i < lines.length; i++) {
int tx;
// if the text is small enough to fit, center it
if (rect.getWidth() < imgWidth) {
tx = (int) (imgWidth / 2 - g2d.getFontMetrics().getStringBounds(lines[i], g2d).getWidth() / 2);
// otherwise, if the table is LTR, ensure the left side of
// the text shows; the right can be clipped
} else if (table.getComponentOrientation().isLeftToRight()) {
tx = 0;
// otherwise, ensure the right side of the text shows
} else {
tx = -(int) (Math.ceil(rect.getWidth()) - imgWidth);
}
int ty = (int) Math.ceil(Math.abs(rect.getY() + i * rect.getHeight() / lines.length));
g2d.drawString(lines[i], tx, ty);
}
}
private void findNextClip(int pw, int ph) {
final boolean ltr = table.getComponentOrientation().isLeftToRight();
// if we're ready to start a new set of rows
if (col == 0) {
if (ltr) {
// adjust clip to the left of the first column
clip.x = 0;
} else {
// adjust clip to the right of the first column
clip.x = totalColWidth;
}
// adjust clip to the top of the next set of rows
clip.y += clip.height;
// adjust clip width and height to be zero
clip.width = 0;
clip.height = 0;
// fit as many rows as possible, and at least one
int rowCount = table.getRowCount();
int rowHeight = table.getRowHeight(row);
do {
clip.height += rowHeight;
if (++row >= rowCount) {
break;
}
rowHeight = table.getRowHeight(row);
} while (clip.height + rowHeight <= ph);
}
// we can short-circuit for JTable.PrintMode.FIT_WIDTH since
// we'll always fit all columns on the page
if (printMode == JTable.PrintMode.FIT_WIDTH) {
clip.x = 0;
clip.width = totalColWidth;
return;
}
if (ltr) {
// adjust clip to the left of the next set of columns
clip.x += clip.width;
}
// adjust clip width to be zero
clip.width = 0;
// fit as many columns as possible, and at least one
int colCount = table.getColumnCount();
int colWidth = colModel.getColumn(col).getWidth();
do {
clip.width += colWidth;
if (!ltr) {
clip.x -= colWidth;
}
if (++col >= colCount) {
// reset col to 0 to indicate we're finished all columns
col = 0;
break;
}
colWidth = colModel.getColumn(col).getWidth();
} while (clip.width + colWidth <= pw);
}
}

And here is the result (I hope that’s what you expect):
JTable with multiple line header when printed

###

You could try

StringBuilder builder = new StringBuilder();
builder.append("Product: ");
builder.append(task.getProductName());
builder.append(System.getProperty("line.separator"));
builder.append("Job: ");
builder.append(task.getJobNumber());
builder.append(System.getProperty("line.separator"));
builder.append("Task: ");
builder.append(task.getTaskID();
MessageFormat header = new MessageFormat(builder.toString());

If this doesn’t work, then you’re going to have to set up your own printer job, and layout the header precisely as you want it.

###

If you use the getPrintable method instead without adding a header/footer text, you can then include/decorate the returned Printable in one where you have more control over the header, and where you can specify multi-line headers. See the javadoc of that method which mentions

It is entirely valid for this Printable to be wrapped inside another in order to create complex reports and documents. You may even request that different pages be rendered into different sized printable areas. The implementation must be prepared to handle this (possibly by doing its layout calculations on the fly). However, providing different heights to each page will likely not work well with PrintMode.NORMAL when it has to spread columns across pages.

I have not enough experience with Printables to help you further on how to actually do this

###

Basically, the answer of @aymeric is correct: there’s no way around a custom printable implementation. A way to do it with slightly less c&p is to have a custom implementation that

  • takes over header/footer printing
  • delegates to table printing itself to the default printable

The trick in that approach is to fool the delegate tablePrintable into believing that the page is smaller than it actually is, with a custom pageFormat

more details (and code)

###

I’ve utilized two MessageFormat arrays as a neat solution to the problem. You’ll find below a printout of the end result:

enter image description here

The code is outlined below:

try    
{
PrinterJob job = PrinterJob.getPrinterJob();
MessageFormat[] header = new MessageFormat[6];
// Assign the arrays with 6 String values for the headers
header[0] = new MessageFormat("");
header[1] = new MessageFormat(theExamSelection);
header[2] = new MessageFormat("");
header[3] = new MessageFormat("Scrud 60 - Grade Returns - Random Sample");
header[4] = new MessageFormat("");
header[5] = new MessageFormat(theSubjectSelection+" - "+theLevelSelection+" - "+thePaperSelection);
MessageFormat[] footer = new MessageFormat[4];
// Assign the 4 Strings to the footer array
footer[0] = new MessageFormat("Assistant Examiner Signature:______________  Date:___ /___ /_____ ");
footer[1] = new MessageFormat("");
footer[2] = new MessageFormat("");
footer[3] = new MessageFormat("Advising  Examiner Signature:______________  Date:___ /___ /_____ ");
//here you place the JTable to print 
// in this case its called randomSample_gradeBreakdown_jTable
// along with the header and footer arrays
job.setPrintable(new PrintTableMultiLine(randomSample_gradeBreakdown_jTable, JTable.PrintMode.FIT_WIDTH, header, footer ));
job.print();
} 
catch (java.awt.print.PrinterException e) 
{
System.err.format("Cannot print %s%n", e.getMessage());
JOptionPane.showMessageDialog(this,
"Check that your printer is working correctly","PRINT ERROR",JOptionPane.ERROR_MESSAGE
);
}