java - Optional in orElse-Branch throws Exception -


this question has answer here:

so i'm working optionals , came across strange behaviour. want know if intendet "feature" or something...odd...

here given example: i've got method optional in orelse want evaluate other optional. if other optional not present, i'll raise illegalargumentexception:

firstoptionalvar.orelse(secondoptionalvar.orelsethrow(illegalargumentexception::new));

now if secondoptionalvar empty optional, raise illegalargumentexception, if firstoptionalvar present. doesn't seem right me. expect raise illegalargumentexception if firstoptionalvar not present.

it's not big deal arround behavior java7-methods like:

firstoptionalvar.ispresent() ? firstoptionalvar.get() : secondoptionalvar.orelsethrow(illegalargumentexception::new);

has else experienced behaviour before? way optionals should behave?

this intended behavior. orelse expects argument of type t (whatever generic type of optional is. orelsethrow returns t, needs evaluated first, in order pass parameter orelse.

what want orelseget, takes supplier<t>. delay execution of orelsethrow until after firstoptionalvar has been checked.

so code should this:

firstoptionalvar.orelseget(() -> secondoptionalvar.orelsethrow(illegalargumentexception::new));

that turn orelsethrow section lambda, , evaluate if it's needed (ie. when firstoptionalvar doesn't have value get).


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