As we know that Java is product of Oracle and Excel is product of Microsoft. Off-course, There will be no standard functionality available in Java to achieve our requirement of creating Excel Sheet. However thanks to Apache for their POI Library. POI Stands for “Poor Obfuscation Implementation” as the file formats created by this library is obfuscated poorly with help of reverse Engineering. Anyways, we don’t have to bother about it and thankful to them for providing such wonderful library.