title: How to change color of a cell of an existing excel (xlsx or xls) in java
body: <p>I have requirement in that i have to read and validate  the excel file and insert to data base, initially i am reading the file and inserting it to database, if the data already there in database, i am returning row and column numbers of the duplicates  from database, i need to change  the color of those cells based on the row and column numbers. </p>
  
  <p>can any one please help me to solve this problem.  or can suggest any idea how to read/ write  and validate excel file, (validation in the sense i need to compare the data in the excel file with the data in the database).</p>
  
  <p>currently i am using apache poi</p>