HSSFSheet.getRow(int) may return null if the row is missing.  This call 
appears to be on line 76 in the latest version.  I can't find a good 
explanation for why your stacktrace says line 77.  If the NPE is really coming 
from 'd.height' (on line 77), then please ignore this posting.

This is the current code:
      Dimension d = getPreferredSize();
      int rowHeight = (int)sheet.getRow(index).getHeightInPoints();
      d.height = rowHeight+extraHeight;

I would propose this fix:
      Dimension d = getPreferredSize();
      HSSFRow row = sheet.getRow(index);
      int rowHeight;
      if(row == null) {
    	  rowHeight = (int)sheet.getDefaultRowHeightInPoints();
      } else {
    	  rowHeight = (int)row.getHeightInPoints();
      }
      d.height = rowHeight+extraHeight;

Created attachment 21571 [details]
svn diff of one changed file

(In reply to comment #1)
> HSSFSheet.getRow(int) may return null if the row is missing.  This call 
> appears to be on line 76 in the latest version.  I can't find a good 
> explanation for why your stacktrace says line 77.  If the NPE is really 
coming 
> from 'd.height' (on line 77), then please ignore this posting.
> This is the current code:
>       Dimension d = getPreferredSize();
>       int rowHeight = (int)sheet.getRow(index).getHeightInPoints();
>       d.height = rowHeight+extraHeight;
> I would propose this fix:
>       Dimension d = getPreferredSize();
>       HSSFRow row = sheet.getRow(index);
>       int rowHeight;
>       if(row == null) {
>     	  rowHeight = (int)sheet.getDefaultRowHeightInPoints();
>       } else {
>     	  rowHeight = (int)row.getHeightInPoints();
>       }
>       d.height = rowHeight+extraHeight;

Yes the correct row is 76, in my cut & paste I have attached the wrong 
StackTrace. Now I rewrite the correct StackTrace:


Exception in thread "main" java.lang.NullPointerException
	at 
org.apache.poi.hssf.contrib.view.SVRowHeader$RowHeaderRenderer.getListCellRender
erComponent(SVRowHeader.java:76)
	at javax.swing.plaf.basic.BasicListUI.updateLayoutState
(BasicListUI.java:1148)
	at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState
(BasicListUI.java:1098)
	at javax.swing.plaf.basic.BasicListUI.getPreferredSize
(BasicListUI.java:281)
	at javax.swing.JComponent.getPreferredSize(JComponent.java:1275)
	at javax.swing.JList.getPreferredScrollableViewportSize(JList.java:1913)
	at javax.swing.ViewportLayout.preferredLayoutSize
(ViewportLayout.java:72)
	at java.awt.Container.preferredSize(Container.java:1178)
	at java.awt.Container.getPreferredSize(Container.java:1162)
	at javax.swing.JComponent.getPreferredSize(JComponent.java:1277)
	at javax.swing.ScrollPaneLayout.layoutContainer
(ScrollPaneLayout.java:717)
	at java.awt.Container.layout(Container.java:1020)
	at java.awt.Container.doLayout(Container.java:1010)
	at java.awt.Container.validateTree(Container.java:1092)
	at java.awt.Container.validateTree(Container.java:1099)
	at java.awt.Container.validateTree(Container.java:1099)
	at java.awt.Container.validateTree(Container.java:1099)
	at java.awt.Container.validateTree(Container.java:1099)
	at java.awt.Container.validateTree(Container.java:1099)
	at java.awt.Container.validateTree(Container.java:1099)
	at java.awt.Container.validate(Container.java:1067)
	at java.awt.Window.show(Window.java:461)
	at java.awt.Component.show(Component.java:1133)
	at java.awt.Component.setVisible(Component.java:1088)
	at org.apache.poi.hssf.contrib.view.SViewerPanel.main
(SViewerPanel.java:287)

Created attachment 21572 [details]
sreenshot of the new problem.

I have made changes described in your attachment (id=21571). Now the table is
correctly displayed, but there's still a little bug: the last row doesn't have
a corresponding row number in the left enumeration column. I attach you a
screenshot of the problem. 
I have some questions, due to I'm a beginnes in submit an issue into a Bugzilla
system: 
1) which version of libraries will have changes, when the issue will be
resolved?
2) what are the formal step that I do to completed this issue?

Thank you in advance.

3) In which version of the library the fix will be delivered? 
Can I include the fixed source code into my distribution, in respect with 
Apache License?

Thanks for the patch Josh, looks just the job. Applied in svn.

I've also fixed the missing row numbers problem, which was caused by calling
getPhysicalNumberOfRows when we meant to call getLastRowNumber. Now works fine
with the version in svn.

Giuseppe - fixes are ASL licensed, so you're welcome to use them under the same
terms as the rest of poi. They're in svn now, will be in tonight's nightly
build, and will be included in the next release

I've tried to perform changes from getPhysicalNumberOfRows to getLastRowNum() 
(getLastRowNumber) in SViewerPanel.java and SVRowHeader.java classes, but the 
bug is still present. I have also noted that the table row was eliminated into 
the .xls file.

Please try with a svn checkout from trunk. 

If the problem remains, please attach a problem excel file so we can test
against that - all my sample files now work just fine.