NullPointerException when reading from xlsx file

Question

I am reading data from an Excel file, which I put later in a MySQL database in the same Java program. I had a problem adding data to the database: Eclipse kept showing a NullPointerException error. I worked with getLastRowNum(), which also counted some empty cells after the filled cells. This problem was fixed with this code (here I only count the amount of filled cells and work with this instead of the last row number):

int rows = Sname.getLastRowNum();
int rows2 = 0;

for(int kk = 1; kk<= rows; kk++)
{
  XSSFRow row = Sname.getRow(kk);
  XSSFCell cell = row.getCell(0);

  if(cell != null)
  {
  rows2++;
  }
}

Last week it worked, but now I get a java.lang.NullPointerException at XSSFCell cell = row.getCell(0);

And I don't understand why. Can somebody help me? Thank you!

Answer 1

我认为您的for应该从0开始而不是从1开始，然后转到rows-1 。

Answer 2

Either Sname.getLastRowNum(); or Sname.getRow(kk) are throwing NPE. Make sure you have initialized Sname

Also Look at your for loop:

for(int kk = 1; kk<= rows; k++)

Does this even compile? If yes, please replace 'k++' with 'kk++' or else you would end up having infinite iterations.

Answer 3

I think the problem is in the limit of the loop. It should go to kk < rows instead of kk <= rows .

In fact, before testing this solution, I would try to log the value for Sname.getLastRowNum() and watch what value it has.