Can't a BufferedReader and a BufferedWriter be open at the same time?

Question

To the experienced:
I am writing a class to selectively extract data from an Excel file, and write out to a plain text file. I am using JDeveloper 11.1.1.3.
It works fine and writes out the output file as expected when reading data from the spreadsheet and directly writing to the output file.
However, I need to convert the data in one of the columns based on a conversion table. The conversion table is a plain text file that has two columns separated by a space. I read in the conversion table using a BufferedReader and put it in a HashMap for use. However, once the Buffered Reader and the HashMap are introduced, the BufferedWriter does not work any more.
The way the class works is that, the main() method (not shown here) reads data from the Excel sheet into a List, and then calls the method showExcelData() (as shown below) to write out data from the List to a plain text file.
When the green color code was not added, the output file was written to the disk fine. A sample line from the output file is:
JOHN:DOE:11223344:12345:20110824By adding the green code, I expect it to output the line as:
JOHN:DOE:11223344:STUDENT:20110824The problem is, after the green code is added, the output file the program writes to the disk is zero size.
I added the System.out.println() lines for troubleshooting. These lines show that the BufferedWriter <b>out</b> is not null, and the conversion is actually taking place. But <b>out.write()</b> simply does not work. Commenting out the green code, the program is working again - of course, without date conversion for that column.
There must be something wrong but I can not see where it is wrong.
Your help is very much appreciated!
Newman
<pre>
private static void showExcelData(List sheetData, String outputFilename) throws IOException {
BufferedWriter out = new BufferedWriter(new FileWriter(outputFilename));
System.out.println("Is out null? " + (out == null));
BufferedReader in = null;
for (int i = 3; i < sheetData.size(); i++) {
List list = (List)sheetData.get(i);
for (int j = 0; j < list.size(); j++) {
HSSFCell cell = (HSSFCell)list.get(j);
if (j == 5 || j == 6 || j == 7 || j == 11) {
<font color="green"><b>
// The column with index 11 is the column of data that needs conversion:
if (j == 11) {
String convertionFilename = "ConversionTable.txt";
Map<String, String> liveMap =
new HashMap<String, String>();
try {
in = new BufferedReader(new FileReader(convertionFilename));
String line = null;
while ((line = in.readLine()) != null) {
String[] keyValue = line.split(" ");
liveMap.put(keyValue[0], keyValue[1]);
} catch (IOException e) {
String message = e.getMessage();
String titleCode =
cell.getRichStringCellValue().toString();
String role = liveMap.get(titleCode).toUpperCase();
out.write(role);
System.out.println(titleCode + " " + role);
} else {</b></font>
out.write(cell.getRichStringCellValue().toString().toUpperCase());
System.out.println(cell.getRichStringCellValue().toString().toUpperCase());<font color="green"><b>
}</b></font>
if (j < list.size() - 1 && j != 11) {
out.write(":");
} else if (j == 26) {
if (cell.getCellType() == HSSFCell.CELL_TYPE_NUMERIC) {
if (DateUtil.isCellDateFormatted(cell)) {
Calendar cellDate = Calendar.getInstance();
cellDate.setTimeInMillis(cell.getDateCellValue().getTime());
String year = "" + cellDate.get(Calendar.YEAR);
String month =
padding(cellDate.get(Calendar.MONTH) + 1);
String day =
padding(cellDate.get(Calendar.DAY_OF_MONTH));
String expDate = year + month + day;
out.write(":" + expDate);
out.write(System.getProperty("line.separator"));
if (in != null) in.close();
if (out != null) out.close();
</pre>

Answer 1

Hi, All,
This posting is at the bottom of the stack. Quite a few more postings were added on top of this and solved, and now I reach back to this one.
The main problems are:
1. Close the I/O buffer after finishing using it. Otherwise the data in the buffer do not get flushed to the file on the disk. I think that is the cause of the problem of getting zero sized output file.
2. Do not count on Excel to stop at a blank cell by using Ctrl-down / Ctrl-up. The file I am processing is produced by some reporting program which, I think, instead of skipping the cell, puts a zero-sized string in it. Obviously, Excel does not stop at such cells. I had checked the columns using the Ctrl-down/Ctrl-up key and through that column did not have blank cells. Sharp-eyed gimbal2 spotted the problem, and led me to re-inspect the column by using up/down arrow keys instead, and found the blank cells. Such empty strings are used in my code as key in searching the map (String role = liveMap.get(titleCode).toUpperCase();) and caused the problem.
And the lesson is, when doing some quick and dirty tests, do not get too quick and too dirty, which can end up slower rather than faster.
Many thank to all of you for giving me the helping hand!
Newman