Java 8 Streams Java Java API
Interface:
java.util.stream.DoubleStream
Method:
<R> R collect(Supplier<R> supplier,
ObjDoubleConsumer<R> accumulator,
BiConsumer<R,R> combiner)
This terminal operation performs a mutable reduction
operation on the elements of this stream.
Type Parameter:
R
- type of the result
Parameters:
supplier
- a function that creates a new result container (mutable object) . For a parallel execution, this function may be called multiple
times. It must return a fresh value each time.
accumulator
- a function for incorporating an additional element into a result.
combiner
- a function for combining two values, used in parallel stream, combines the results received from different threads.
Examples
 package com.logicbig.example.doublestream;
import java.util.stream.DoubleStream;
public class CollectExample {
public static void main(String... args) {
DoubleStream ds = DoubleStream.of(1.01, 1.2, 1.4, 1.6, 2.4, 2.7);
//collect product of rounded doubles
long result = ds.parallel()
.collect(() -> new long[]{1},
(longs, value) ->
longs[0] = Math.multiplyExact(longs[0], Math.round(value)),
(longs, longs2) ->
longs[0] = Math.multiplyExact(longs[0], longs2[0])
)[0];
System.out.println(result);
}
}
Output12
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