What is the purpose of long, double, byte, char in Java?

Question

So I\'m learning java, and I have a question. It seems that the types int, boolean and string will be good for just about everything I

Answer 1

The primitive data types are required because they are the basis of every complex collection.

long, double, byte etc. are used if you need only a small integer (or whatever), that does not waste your heap space.

I know, there's enough of RAM in our times, but you should not waste it.

I need the "small ones" for database and stream operations.