title: Writing to an Excel cell erases all other existing data in that particular row
body: <p>I have an existing Excel file, in which I need to update some cell data.</p>
  <p>I am reading the xlsx file like this:</p>
  <pre><code>File file = Paths.get(&quot;location/template.xlsx&quot;).toFile();
  Workbook workbook = WorkbookFactory.create(file);
  </code></pre>
  <p>Then I am updating the cell like this:</p>
  <pre><code>Sheet sheet = workbook.getSheet(sheetName);
  Row row = sheet.createRow(cellRowNum); //because sheet.getRow(cellRowNum) was returning null.
  Cell cell = row.createCell(cellColumnNum);
  cell.setCellValue(value);
  </code></pre>
  <p>So now, the value is correctly visible on the cell, but all other existing data in that row is erased/overwritten.</p>
  <p>Please help me figure this out? I need to use Apache POI only.</p>