CODEWITHSUNDEEP
lambdacollectionsjava-8functional-programmingjava-stream
en Peris
en Peris

Reputation: 1717

Java8 lambda: sort a stream in reverse order?

I have this list that I want to order in reserve order, but I didn't find any .reversed() function in autocomplete assist

 myMenus(user)
                .stream()
                .filter(mps ->  mps.get1PercentageChange() > 0 &&
                                mps.get2PercentageChange() > 0 &&
                                mps.get3PercentageChange() > 0 &
                                mps.get4PercentageChange() > 0)
                .sorted(comparing(mps -> mps.getDailyPercentageChange()))
                .collect(toList());

I have also tried:

myMenus(user)
        .stream()
        .filter(mps ->  mps.get1PercentageChange() > 0 &&
                        mps.get2PercentageChange() > 0 &&
                        mps.get3PercentageChange() > 0 &
                        mps.get4PercentageChange() > 0)
        .sorted(comparing(mps -> mps.getDailyPercentageChange()).reversed())
        .collect(toList());

but then I have the compilation error:

Cannot infer type argument(s) for <T, U> comparing(Function<? super T,? 
     extends U>)

Upvotes: 6

Views: 11277

Answers (2)

Ousmane D.
Ousmane D.

Reputation: 56433

It's a type inference issue. You'll need to help the compiler out.

few things you could try:

.sorted(comparing(T::getDailyPercentageChange).reversed())

or

.sorted(comparing((T mps) -> mps.getDailyPercentageChange()).reversed())

Where T is the type of elements being compared.

Upvotes: 8

Jean-Baptiste Yun&#232;s
Jean-Baptiste Yun&#232;s

Reputation: 36401

Comparators have a reversed method to get the reverse ordering, so :

.sorted(comparing(mps -> mps.getDailyPercentageChange()).reversed())

should work.

Upvotes: 5

Related Questions