使用poi和hashmap编写Excel工作表

Question

I am attempting to write an excel sheet using POI and hashMaps. My code successfully creates and populates an excel sheet but not all of the information is written to the sheet. In debug mode it seems to write 5 key, value pairs and then loops to the start at key [0]. Can someone tell me where the mistake is in my logic?

HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet(make + " sheet");
        int rowNum = 0;
        ConcurrentHashMap <Integer, String[] > data = new 
                        ConcurrentHashMap<Integer, String[]>();

        data.put(rowNum++, new String[] {"VIN", "Make", "Model", "Year", 
                        "Major Group", "Caption", "Cap Filter", "Illustration",
                        "Illus Filter", "PNC", "Part Name", "Part Number", "Quantity",
                        "Part Filter"});

        for (Part p : plist){
            String PNC = p.getPNC();
            String quantity = p.getQuantity();

            if(vFilterId.contains(p.getId())) {
                data.put(rowNum++ , new String[] {vinId, make, 
                                    model, year, group, caption, capFilter, illusName,
                                    iFilter, PNC, p.getName(), p.getPartNumber(), 
                                    quantity, "NONFILTERED"});

            } else {
                data.put(rowNum++ , new String[] {vinId, make, 
                                    model, year, group, caption, capFilter, illusName,
                                    iFilter, PNC, p.getName(), p.getPartNumber(), 
                                    quantity, "NONFILTERED"});

            }

        }
        int rowIndex = 0;
        Set<Integer> keyset = data.keySet();
        for (Integer key : keyset) {
            Row row = sheet.createRow(rowIndex++);
            Object[] objArr = data.get(key);
            int cellIndex = 0;
            for (Object obj : objArr) {
                Cell cell = row.createCell(cellIndex++);
                cell.setCellValue((String) obj);
            }

        }

        try {
            FileOutputStream fos = new FileOutputStream(outputFile);
            workbook.write(fos);
            fos.close();
            System.out.println("XLS sheet written.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return ReturnConstants.SUCCESS;
}

Thanks in advance!

Answer 1

You're using a map to store data representing rows in a table. You'd be better off using a List since maps are generally not sorted (ie the order of the entries might change over time).

HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet(make + " sheet");
List<String[]> data = new ArrayList<String[]>();

data.add(new String[] {"VIN", "Make", "Model", "Year", 
        "Major Group", "Caption", "Cap Filter", "Illustration",
        "Illus Filter", "PNC", "Part Name", "Part Number", "Quantity",
"Part Filter"});

for (Part p : plist){
    String PNC = p.getPNC();
    String quantity = p.getQuantity();

    if(vFilterId.contains(p.getId())) {
        data.add(new String[] {vinId, make, 
                model, year, group, caption, capFilter, illusName,
                iFilter, PNC, p.getName(), p.getPartNumber(), 
                quantity, "NONFILTERED"});

    } else {
        data.add(new String[] {vinId, make, 
                model, year, group, caption, capFilter, illusName,
                iFilter, PNC, p.getName(), p.getPartNumber(), 
                quantity, "NONFILTERED"});

    }

}
for (int rowIndex=0; rowIndex<data.size(); rowIndex++) {
    Row row = sheet.createRow(rowIndex);
    Object[] objArr = data.get(rowIndex);
    int cellIndex = 0;
    for (Object obj : objArr) {
        Cell cell = row.createCell(cellIndex++);
        cell.setCellValue((String) obj);
    }
}

Answer 2

It's hard to determine without debugging your code, but from what you described it seems like your keyset variable contains only 3 entries, which is why you are outputting only 3 rows. So the first thing I would do would be to display (using System.out.println) data.size() and keyset.size() to see how big they are. I am guessing one or both are only of size 3.

Did you show all the relevant code? I think perhaps not, because, for example, your if statement seems redundant as you output the same thing regardless of whether you execute the if code or else clause.

I do agree with the first answer that there is no need to use a HashMap; an ArrayList will work just as well. But, as you discovered, that has nothing to do with why you are only seeing 3 rows.

Sorry I can't be more helpful, but I think some debugging on your part with System.out.println will go a long way in discovering what the problem is.