package com.github.java8.lambdasinaction.chap5;
import java.util.*;
import java.util.function.IntSupplier;
import java.util.stream.*;
import java.nio.charset.Charset;
import java.nio.file.*;
public class BuildingStreams {
public static void main(String...args) throws Exception{
// Stream.of
Stream<String> stream = Stream.of("Java 8", "Lambdas", "In", "Action");
stream.map(String::toUpperCase).forEach(System.out::println);
// Stream.empty
Stream<String> emptyStream = Stream.empty();
// Arrays.stream
int[] numbers = {2, 3, 5, 7, 11, 13};
System.out.println(Arrays.stream(numbers).sum());
// Stream.iterate
Stream.iterate(0, n -> n + 2)
.limit(10)
.forEach(System.out::println);
// fibonnaci with iterate
Stream.iterate(new int[]{0, 1}, t -> new int[]{t[1],t[0] + t[1]})
.limit(10)
.forEach(t -> System.out.println("(" + t[0] + ", " + t[1] + ")"));
Stream.iterate(new int[]{0, 1}, t -> new int[]{t[1],t[0] + t[1]})
.limit(10)
. map(t -> t[0])
.forEach(System.out::println);
// random stream of doubles with Stream.generate
Stream.generate(Math::random)
.limit(10)
.forEach(System.out::println);
// stream of 1s with Stream.generate
IntStream.generate(() -> 1)
.limit(5)
.forEach(System.out::println);
IntStream.generate(new IntSupplier(){
public int getAsInt(){
return 2;
}
}).limit(5)
.forEach(System.out::println);
IntSupplier fib = new IntSupplier(){
private int previous = 0;
private int current = 1;
public int getAsInt(){
int nextValue = this.previous + this.current;
this.previous = this.current;
this.current = nextValue;
return this.previous;
}
};
IntStream.generate(fib).limit(10).forEach(System.out::println);
long uniqueWords = Files.lines(Paths.get("com/github/java8/lambdasinaction/chap5/data.txt"), Charset.defaultCharset())
.flatMap(line -> Arrays.stream(line.split(" ")))
.distinct()
.count();
System.out.println("There are " + uniqueWords + " unique words in data.txt");
}
}