How to make a selection from a sheet?

Question

Java

Good afternoon!
I get a table of this type from the database
Firm Goods
---------------------
Firm1 printer
Firm1 fax
Firm1 telephone
Firm2 potatoes
Firm3 vacuum cleaner
Firm3 notepad
How to write the processing of this sheet so that get the output in the console like:
Firm1 - printer, fax, phone
Firm2 - potatoes
Firm3 - vacuum cleaner, notepad
I can only iterate through the iterator and compare everything with everything. Put the first name of the company into a temporary variable. We compare the elements of the sheet with this variable by the name of the company, if the names of the companies match, then prints the product in a line. Delete a line from a sheet. Etc.
Maybe there are some other optimal solutions? And then if the table has 1,000,000 rows, then the speed will be depressing.
Thanks in advance.

Answer 1

map = list. stream().collect(groupingBy(Db::getForm)) ;
If 8 already.