Excel Formula is not updated when the reference sheet is updated using a Java program

Hi,

I have 3 worksheets, "Sheet1" and Sheet2 have values and Sheet 3 has formula like "=IF(Shee1!A2=Sheet2!A2, "Pass ", "Fail")".

I 'm updating sheet2 using a Java program. But once the sheet is updated, when I reopen the excel sheet, the values in Sheet3 are not refreshed automatically. 

To update the values, I have to click on each cell and hit enter.

How can I make the formula result to update automatically when I open it after each update on Sheet 2.

Please note that I have Excel 2013 but my Java program saves it in xls format.

Please help.

Thanks,

Vaishnavi