使用jxl库在Java中向Excel文件的单元格添加注释

Question

使用jxl库在Java中向Excel文件的单元格添加注释

5

我正在尝试向Excel单元格添加注释。我使用jxl库来完成这项工作：

   cell = sheet.getWritableCell(1, 2); // cols, rows
   WritableCellFeatures wcf = cell.getWritableCellFeatures();
   wcf.setComment("comment2");

最后一行返回：Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException。尽管我尝试了很多次，但无法修复它。希望能得到帮助。谢谢。

--编辑-- 这是修改后的addNumber方法：

private static void addNumber(WritableSheet sheet, int column, int row,
        double d) throws WriteException, RowsExceededException {

    Number number;
    number = new Number(column, row, d, timesStandard);

    //sheet.addCell(number); // need to add the cell first

    if (user wants to add a comment) {
        WritableCellFeatures wcf = new WritableCellFeatures();
        wcf.setComment("the comment");
        number.setCellFeatures(wcf);
    }

    //sheet.addCell(number); // but may need to add the cell with comments as well
}

- Hurdler

1

cell.getWritableCellFeatures()返回空值，因为该单元格没有任何特性。尝试使用WritableCellFeatures wcf = new WritableCellFeatures(); wcf.setComment("comment"); cell.setCellFeatures(wcf);。 - alain.janinm

1

在你的if语句中，你能加上Cell cell = sheet.getWritableCell(column, row);，然后用cell.setCellFeatures(wcf);替换number.setCellFeatures(wcf);吗？ - alain.janinm

我添加了 WritableCell cell = sheet.getWritableCell(column, row); 并将 number 替换为 cell，但是注释不见了。 - Hurdler

那么你将 sheet.addCell(number); 替换为 sheet.addCell(cell);？ - alain.janinm

2个回答

2

从评论和以下文档：

我做了这个:

private static void addNumber(WritableSheet sheet, int column, int row,
    double d) throws WriteException, RowsExceededException {

   Number number;
   number = new Number(column, row, d, timesStandard);

   sheet.addCell(number);

   if (user wants to add a comment) {
     WritableCell cell = sheet.getWritableCell(column, row)
     Label l = (Label) cell;
     WritableCellFeatures cellFeatures = new WritableCellFeatures();
     cellFeatures.setComment("the cell comment");
     l.setCellFeatures(cellFeatures);
     sheet.addCell(l);
  }

}

- alain.janinm

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可以查看英文原文，
原文链接

- Torious · Accepted Answer

您之前是否在该位置添加过单元格？问题在于您无法在空单元格上设置单元格特性，它总是会返回null作为其单元格特性。

如果您首先添加一个单元格，则可以解决此问题（为了清晰起见，省略了try/catch），如下所示的代码。请注意，它还首先在新的Label单元格上设置了WritableCellFeatures，因为最初，单元格特性始终为null。

            WritableWorkbook book = Workbook.createWorkbook(new File("output.xls"));
            WritableSheet sheet = book.createSheet("Some Sheet", 0);

            Label label = new Label(1, 2, "Some label"); 
            sheet.addCell(label); // add cell!

            WritableCellFeatures wcf = new WritableCellFeatures();
            wcf.setComment("Hello!");

            // set cell features!
            label.setCellFeatures(wcf);

            book.write();
            book.close();

使用此方法与 OP 中的方法：

我修改了该方法，以返回创建的（并添加的！）Number 实例。如果您不想这样做，您可以使用相同行/列使用 WritableWorkbook.getWritableCell() 检索相同单元格。

public static void main(String[] args) throws IOException, RowsExceededException, WriteException {

    File file = new File("output.xls");
    WritableWorkbook workbook = Workbook.createWorkbook(file);
    WritableSheet sheet = workbook.createSheet("First Sheet", 0);

    Number number = addNumber(sheet, 3, 2, 565d);

    WritableCellFeatures wcf = number.getWritableCellFeatures();
    if (wcf == null) wcf = new WritableCellFeatures();
    wcf.setComment("the comment");
    number.setCellFeatures(wcf);

    workbook.write(); 
    workbook.close();

}

private static Number addNumber(WritableSheet sheet, int column, int row,
        double d) throws WriteException, RowsExceededException {

    Number number = new Number(column, row, d, timesStandard);
    sheet.addCell(number); // need to add the cell first
    return number;
}