NullPointerException当尝试将结果写入excel时 [英] NullPointerException when try to write result to excel
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问题描述
我收到有关第41行的NullPointerException的错误消息。我知道它返回null，但这个值是下列验证所必需的。一般的任务是将结果写入excel文件。
public class ExcelUtils {
public static void main（String [] args）
{
//空白工作簿
XSSFWorkbook工作簿=新XSSFWorkbook（）;
//创建一个空白页
XSSFSheet sheet = workbook.createSheet（Employee Data）;
String Result =TEST TEST TEST;
int RowNum = 2;
int ColNum = 3;
XSSFSheet ExcelWSheet = sheet;
XSSFCell Cell;
XSSFRow行;
尝试
{
Row = ExcelWSheet.getRow（RowNum）;
Cell = Row.getCell（ColNum，org.apache.poi.ss.usermodel.Row.RETURN_BLANK_AS_NULL）;
if（Cell == null）{
Cell = Row.createCell（ColNum）;
Cell.setCellValue（Result）;
} else {
Cell.setCellValue（Result）;
}
// ------------------- --------------------------------
//尝试
// {
//在文件系统中写入工作簿
FileOutputStream out = new FileOutputStream（new File（howtodoinjava_demo.xlsx））;
workbook.write（out）;
out.close（）;
System.out.println（howtodoinjava_demo.xlsx在磁盘上成功写入）;
}
catch（异常e）
{
e.printStackTrace（）;
}
}
}
解决方案
将Result字符串从测试方法传递给writeexcel方法。您不需要创建一个对象，因为方法是静态的
writeexcel（pass，2,3）;
这将调用writeexcel方法，并将作为参数传递的字符串ie）pass
public static void writeexcel（String Result，int RowNum，int ColNum）
{
//空白工作簿
XSSFWorkbook工作簿=新的XSSFWorkbook（）;
//创建一个空白页
XSSFSheet sheet = workbook.createSheet（Employee Data）;
XSSFSheet ExcelWSheet = sheet;
XSSFCell Cell;
XSSFRow行;
try
{
Row = ExcelWSheet.createRow（RowNum）;
Cell = Row.getCell（ColNum，org.apache.poi.ss.usermodel.Row.RETURN_BLANK_AS_NULL）;
if（Cell == null）{
Cell = Row.createCell（ColNum）;
Cell.setCellValue（Result）;
} else {
Cell.setCellValue（Result）;
}
FileOutputStream out = new FileOutputStream（new File（howtodoinjava_demo.xlsx））;
workbook.write（out）;
out.close（）;
System.out.println（howtodoinjava_demo.xlsx在磁盘上成功写入）;
}
catch（异常e）
{
e.printStackTrace（）;
}
}
编辑
public class Tests {
static XSSFWorkbook workbook = new XSSFWorkbook（）;
static XSSFSheet sheet = workbook.createSheet（Employee Data）;
public static void main（String [] args）{
int j = 3; （int i = 2; i< = 5; i ++）
{
String result =Test+ i;
writeexcel（result，i，j）;
}
writetoexcel（）; //写入单元格（2,3），（3,3），（4,3）
}
public static void writeexcel（String Result，int RowNum，int ColNum）
{
//创建一个空白页
XSSFSheet ExcelWSheet = sheet;
XSSFCell Cell;
XSSFRow行;
try
{
Row = ExcelWSheet.createRow（RowNum）;
Cell = Row.getCell（ColNum，org.apache.poi.ss.usermodel.Row.RETURN_BLANK_AS_NULL）;
if（Cell == null）{
Cell = Row.createCell（ColNum）;
Cell.setCellValue（Result）;
} else {
Cell.setCellValue（Result）;
}
}
catch（异常e）
{
e.printStackTrace（）;
}
}
public static void writetoexcel（）{
try {
FileOutputStream out = new FileOutputStream（new File（howtodoinjava_demo .XLSX））;
workbook.write（out）;
out.close（）;
System.out.println（howtodoinjava_demo.xlsx在磁盘上成功写入）;
} catch（Exception e）
{
e.printStackTrace（）;
}
}
}
希望这个帮助你...如果您需要任何帮助，请回复
Can someone help with this code?
I receive an error message about NullPointerException at 41 row. I know that it returns null but this value is required for following verification. The general task is to write result to excel file.
public class ExcelUtils {
public static void main(String[] args)
{
//Blank workbook
XSSFWorkbook workbook = new XSSFWorkbook();
//Create a blank sheet
XSSFSheet sheet = workbook.createSheet("Employee Data");
String Result = "TEST TEST TEST";
int RowNum = 2;
int ColNum = 3;
XSSFSheet ExcelWSheet = sheet;
XSSFCell Cell;
XSSFRow Row;
try
{
Row = ExcelWSheet.getRow(RowNum);
Cell = Row.getCell(ColNum, org.apache.poi.ss.usermodel.Row.RETURN_BLANK_AS_NULL);
if (Cell == null) {
Cell = Row.createCell(ColNum);
Cell.setCellValue(Result);
} else {
Cell.setCellValue(Result);
}
//---------------------------------------------------
//try
// {
//Write the workbook in file system
FileOutputStream out = new FileOutputStream(new File("howtodoinjava_demo.xlsx"));
workbook.write(out);
out.close();
System.out.println("howtodoinjava_demo.xlsx written successfully on disk.");
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
解决方案
pass the Result string from your test method to the method writeexcel.You don't need to create an object as the method is static
writeexcel("pass",2,3);
This will call the writeexcel method and will write the string passed as an argument ie) "pass" in the respective cell
Method :
public static void writeexcel(String Result,int RowNum ,int ColNum)
{
//Blank workbook
XSSFWorkbook workbook = new XSSFWorkbook();
//Create a blank sheet
XSSFSheet sheet = workbook.createSheet("Employee Data");
XSSFSheet ExcelWSheet = sheet;
XSSFCell Cell;
XSSFRow Row;
try
{
Row = ExcelWSheet.createRow(RowNum);
Cell = Row.getCell(ColNum, org.apache.poi.ss.usermodel.Row.RETURN_BLANK_AS_NULL);
if (Cell == null) {
Cell = Row.createCell(ColNum);
Cell.setCellValue(Result);
} else {
Cell.setCellValue(Result);
}
FileOutputStream out = new FileOutputStream(new File("howtodoinjava_demo.xlsx"));
workbook.write(out);
out.close();
System.out.println("howtodoinjava_demo.xlsx written successfully on disk.");
}
catch (Exception e)
{
e.printStackTrace();
}
}
EDIT
public class Tests {
static XSSFWorkbook workbook = new XSSFWorkbook();
static XSSFSheet sheet = workbook.createSheet("Employee Data");
public static void main(String[] args) {
int j=3;
for(int i=2;i<=5;i++) {
String result = "Test "+i;
writeexcel(result, i, j);
}
writetoexcel();//write to cell(2,3),(3,3),(4,3)
}
public static void writeexcel(String Result,int RowNum ,int ColNum)
{
//Create a blank sheet
XSSFSheet ExcelWSheet = sheet;
XSSFCell Cell;
XSSFRow Row;
try
{
Row = ExcelWSheet.createRow(RowNum);
Cell = Row.getCell(ColNum, org.apache.poi.ss.usermodel.Row.RETURN_BLANK_AS_NULL);
if (Cell == null) {
Cell = Row.createCell(ColNum);
Cell.setCellValue(Result);
} else {
Cell.setCellValue(Result);
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
public static void writetoexcel(){
try{
FileOutputStream out = new FileOutputStream(new File("howtodoinjava_demo.xlsx"));
workbook.write(out);
out.close();
System.out.println("howtodoinjava_demo.xlsx written successfully on disk.");
}catch (Exception e)
{
e.printStackTrace();
}
}
}
Hope this helps you...Kindly get back if you need any further help
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