What Library file should be included to write PDF file in JAVA?

[Gobindap]

I am using Netbeans to develop software. For this I tried some code as suggested by experts. But codes displayed error sign. I feel my library files are missing and I need to include them.

To write PDF and EXCEL what library files are required?
Will you please help my?

[PreethiGowri]

iText
Apache PDF box
BFO