Read/write to same excel file using Apache POI

Read/write to same excel file using Apache POI

i want to read an excel and write to the same excel based on some
conditions. for example
Empno Name Salary
1 jonh 2000
2 Sam 3000
3 Dean 7000
Now my requrient is
1) want to read the data based on column name say 'Name' and get all the
data under that column
2) in the same way based on the column name say 'Name' i want to add one
more row of data ie data should be in the following way after adding new
row to same excel file
Empno Name Salary
1 jonh 2000
2 Sam 3000
3 Dean 7000
4 Smith 8000
how to do this using Apache POI.
can anybody provide me an example . i want to read/read to the same excel
donot want to create a new excel.
thanks in advance.