How to create a map with Java stream API using a value outside the stream?

Question

I want to init a Map and want to always put the same BigDecimal value from outside of the stream.

BigDeci         


        

Answer 1

The second argument (like the first one) of toMap(keyMapper, valueMapper) is a function that takes the stream element and returns the value of the map.

In this case, you want to ignore it so you can have:

set.stream().collect(Collectors.toMap(Function.identity(), e -> samePrice));

Note that your second attempt wouldn't work for the same reason.