如何填充没有空行的xls文件？

Question

我想在我的项目上生成一个excel文件。我的目标是显示在这个特定部门分配的所有部门和所有学生。到目前为止，这就是我所做的：

...
int rowNum = 4;//From row 0 to 3 was occupied as Header
for (Department department : departments) {
    Row row = sheet.createRow(rowNum++);
    row.createCell(0).setCellValue(department.getName());
    for (Students student: students) {
        row = sheet.createRow(rowNum++);
        if (department.getId() == student.getDepartmentId()) {
            row.createCell(0).setCellValue(student.getIdNumber());
            //and all other info such as name, gender, dob
        }
    }
}

如果选择了一个部门，那么它工作正常，但如果我选择获得所有部门，我的输出如下：

Department A
//blank rows of about 20 were produced
201901010          Student A          Male          ...
201901011          Student B          Male          ...
//blank rows of about 950
Department B
//blank rows of about 40
201901071          Student X          Male          ...
201901072          Student Z          Male          ...
//blank rows of about 963
...

我想要的是这样的：

Department A
201901010          Student A          Male          ...
201901011          Student B          Male          ...
Department B
201901071          Student X          Male          ...
201901072          Student Z          Male          ...
...

我在rowNum变量上尝试了不同的东西但它们都不起作用。有些人打印了我所有的部门和很多空白行，然后打印出最后一部门下的学生名单。

Answer 1

我只是注意到我的代码结构错误：

if (department.getId() == student.getDepartmentId()) {
    row = sheet.createRow(rowNum++);
    ....
}

代替：

row = sheet.createRow(rowNum++);
if (department.getId() == student.getDepartmentId()) {
    row.createCell(0).setCellValue(student.getIdNumber());
    ...
}