New FAQ.

git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@352586 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/src/documentation/xdocs/faq.xml b/src/documentation/xdocs/faq.xml
index c038e3b51e88e9e0736f2ad06d1a8f2fd4f7a206..887ea30da9bcefa37756dcf966aa30589cb0a70a 100644 (file)
--- a/src/documentation/xdocs/faq.xml
+++ b/src/documentation/xdocs/faq.xml
@@ -42,4 +42,72 @@
             at this feel free to add it as a plugin module.  We wont be hosting it here however.
         </answer>
     </faq>
+    <faq>
+        <question>
+            How do you tell if a field contains a date with HSSF?
+        </question>
+        <answer>
+            Excel stores dates as numbers therefore the only way to determine if a cell is
+            actually stored as a date is to look at the formatting. This solution from
+            Jason Hoffman:
+            <p>
+            Okay, here is a little code I used to determine if the cell was a number or
+            date, and then format appropriately.  I hope it helps.  I keep meaning to
+            submit a patch with the helper method below.... but just haven't had a
+            chance.
+            </p>
+            <source>
+/////// code snippet ////////////
+case HSSFCell.CELL_TYPE_NUMERIC:
+                  double d = cell.getNumericCellValue();
+                  // test if a date!
+                  if (isCellDateFormatted(cell)) {
+                    // format in form of M/D/YY
+                    cal.setTime(HSSFDateUtil.getJavaDate(d));
+                    cellText =
+                      (String.valueOf(cal.get(Calendar.YEAR))).substring(2);
+                    cellText = cal.get(Calendar.MONTH)+1 + "/" +
+                               cal.get(Calendar.DAY_OF_MONTH) + "/" +
+                               cellText;
+                  }
+/////// end code snippet ////////////
+
+// HELPER METHOD BELOW TO DETERMINE IF DATE
+
+// method to determine if the cell is a date, versus a number...
+public static boolean isCellDateFormatted(HSSFCell cell) {
+    boolean bDate = false;
+
+    double d = cell.getNumericCellValue();
+    if ( HSSFDateUtil.isValidExcelDate(d) ) {
+      HSSFCellStyle style = cell.getCellStyle();
+      int i = style.getDataFormat();
+      switch(i) {
+        // Internal Date Formats as described on page 427 in
+        // Microsoft Excel Dev's Kit...
+        case 0x0e:
+        case 0x0f:
+        case 0x10:
+        case 0x11:
+        case 0x12:
+        case 0x13:
+        case 0x14:
+        case 0x15:
+        case 0x16:
+        case 0x2d:
+        case 0x2e:
+        case 0x2f:
+         bDate = true;
+        break;
+
+        default:
+         bDate = false;
+        break;
+      }
+    }
+    return bDate;
+  }
+            </source>
+        </answer>
+    </faq>
 </faqs>