Today I was creating a Java Program to read a Excel files (created by importing text log files) using POI HSSF and faced the following errors:
java.io.IOException: Invalid header signature; read 8751655596022002505, expected -2226271756974174256 .
After a analysis i found that the excel file I am using is not an Excel binary file. It's a text file with a .xls extension s.t. Excel can quietly convert it and display as a spreadsheet. HSSF deals with files written in Excel format only.
I used the Save As… command to save that file as Excel . And now the problem is Solved :).