tutorial8_DAJK-JAVA_Meat_源码

package tutorial8.t8; import java.util.ArrayList; import java.util.Arrays; import java.util.IntSummaryStatistics; import java.util.Random; import java.util.function.Function; import java.util.stream.Collectors; import java.util.stream.DoubleStream; import java.util.stream.IntStream; import java.util.stream.Stream; public class javaStreamsTemplate { static int size = 1000; static double[] myList = new Random().doubles(size).toArray(); static void timeSumSequential() { System.out.println(" Summing sequentially:"); Op.timeOp(() -> { double theSum = DoubleStream.of(myList).map(Math::sqrt).sum(); // your code to compute sum of square roots System.out.printf(" Sum is %,.8f.%n", theSum); });} static void timeSumParallel() { System.out.println(" Summing in parallel:"); Op.timeOp(() -> {double theParallelSum=DoubleStream.of(myList).parallel().map(Math::sqrt).sum(); // your code to compute sum of square roots in parallel System.out.printf(" Sum is %,.8f.%n", theParallelSum); }); } static boolean isprime(Integer max){ return IntStream.range(2,max).noneMatch(i->max%i==0); } static int factorial(Integer x){ int sum=1; for (int i =1;i<=x;i++){ sum=sum*i; } return sum; } public static void main(String[] args) { Stream<Integer> odds =Stream.iterate(1,x->x+2); Stream<Integer> stream = Stream.iterate(0,i->i+1); Stream<Double> powers = stream.map(x -> Math.pow(2,x)); Stream<Integer> stream1 = Stream.iterate(0, i->i+1); Function<Integer,Stream<Integer>>repeat=x->Stream.of(x,x,x); Stream<Integer> repeats=stream1.flatMap(repeat); Stream<Integer> stream2 = Stream.iterate(0,i->i+1); Stream<Integer> facts = stream2.map(x->factorial(x)); Stream<Integer> streams=Stream.iterate(0,i->i+1); Stream<Integer> primes= streams.filter(i->isprime(i)); odds.limit(10).forEach(System.out::println); powers.limit(10).forEach(System.out::println); repeats.limit(10).forEach(System.out::println); facts.limit(10).forEach(System.out::println); primes.limit(10).forEach(System.out::println); timeSumSequential(); timeSumParallel(); } }