106 replies

how to read and understand the map() method signature?

hey guys. can smb help me out? Im messing around with streams and

map()

map()

and im trying to understand how it works. in the ide i see this

<R> Stream<R> map(Function<? super T, ? extends R> mapper);

<R> Stream<R> map(Function<? super T, ? extends R> mapper);

can smb explain what the f is this? as always, google is worthless and gooling raises more questins than it gives u answers.
1. as i understand,

map

map

function returns

Stream

Stream

, but what do those

mean?
2.

map

map

function has a parameter called

mapper

mapper

right? and its of type

Function<? super T, ? extends R>

Function<? super T, ? extends R>

?
3. how to undertand this stuff?

Function<? super T, ? extends R>

Function<? super T, ? extends R>

thanks alot guys.