About Question enthuware.ocpjp.ii.v11.2.1882 :

[sir_Anduin@yahoo.de]

is there any pattern for count, size, length and their return type?
maybe all new api return long from count?

[admin]

Generally, size and length are int and count and sum are in long. But you should not rely on it because there is no documented rule. You might see a method that doesn't follow it.

[codeappman@gmail.com]

count is always long/Long.

In IntStream, LongStream, DoubleStream
long count()

In Collectors
Long counting()

size() in List is 'int', length in array and string is also 'int'. However, these two are too fundamental, I think it's unlikely to trick you with them in OCPJP.

[kevvvvyp]

Generally, size and length are int and count and sum are in long. But you should not rely on it because there is no documented rule. You might see a method that doesn't follow it.

With regards to sum:
- IntStream sum() returns int
- DoubleStream sum() returns double
- LongStream sum() returns long