Sorting Rows in Excel with POI - apache-poi

Question

I'm trying to sort an XSSF sheet in POI and I'm not having any luck. I found a prior post saying the issue with shifting rows was fixed in 3.9 but I'm still getting an error. I tried using the method below and this is the error I'm getting..
/**
* Sorts (A-Z) rows by String column
* #param sheet - sheet to sort
* #param column - String column to sort by
* #param rowStart - sorting from this row down
*/
private void sortSheet(Sheet sheet, int column, int rowStart) {
boolean sorting = true;
int lastRow = sheet.getLastRowNum();
while (sorting == true) {
sorting = false;
for (Row row : sheet) {
// skip if this row is before first to sort
if (row.getRowNum()<rowStart) continue;
// end if this is last row
if (lastRow==row.getRowNum()) break;
Row row2 = sheet.getRow(row.getRowNum()+1);
if (row2 == null) continue;
String firstValue = (row.getCell(column) != null) ? row.getCell(column).getStringCellValue() : "";
String secondValue = (row2.getCell(column) != null) ? row2.getCell(column).getStringCellValue() : "";
//compare cell from current row and next row - and switch if secondValue should be before first
if (secondValue.compareToIgnoreCase(firstValue)<0) {
sheet.shiftRows(row2.getRowNum(), row2.getRowNum(), -1);
sheet.shiftRows(row.getRowNum(), row.getRowNum(), 1);
sorting = true;
}
}
}
Exception in thread "AWT-EventQueue-0" org.apache.xmlbeans.impl.values.XmlValueDisconnectedException
at org.apache.xmlbeans.impl.values.XmlObjectBase.check_orphaned(XmlObjectBase.java:1258)
at org.openxmlformats.schemas.spreadsheetml.x2006.main.impl.CTRowImpl.getR(Unknown Source)
at org.apache.poi.xssf.usermodel.XSSFRow.getRowNum(XSSFRow.java:322)
at Objects.Event.sortSheet(Event.java:426)
at Objects.Event.writeRigSheetsAverages(Event.java:394)
at Objects.GroupInfo.seperateRigTypes(GroupInfo.java:138)
at Objects.GroupInfo.<init>(GroupInfo.java:46)
at DowntimeReports.StartProgram(DowntimeReports.java:135)
at DowntimeReports.<init>(DowntimeReports.java:52)
at DowntimeGUI.actionPerformed(DowntimeGUI.java:89)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
My sheet starts with 5 rows but when I make the shift it gets reset to 3.