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class NumericStreams {
public static void main(String[] args) {
List<Book> list = new ArrayList<>();
list.add(new Book("The Alchemist", "Paulo Coelho", "Adventure", 4.408789797));
list.add(new Book("The Notebook", "Nicholas Sparks", "Romance", 4.10));
list.add(new Book("Horror Cocktail", "Robert Bloch", "Horror", 2.67));
list.add(new Book("House of Leaves", "Mark Z. Danielewski", "Horror", 4.10908908));
OptionalDouble average = list.stream()
.mapToDouble(book -> book.getRating())
.average();
System.out.println(average.getAsDouble());
//map : Objects
//mapToDouble : primitive double
IntStream intS = IntStream.of(1,3,5,8);
DoubleStream doubleS = DoubleStream.of(1,3,5,8);
LongStream longS = LongStream.of(1L,3L,5L,8L);
Stream<Integer> boxedInts = intS.boxed();
doubleS.mapToObj(val -> val);
}
}
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class Calculations {
public static void main(String[] args) {
//IntStream
//DoubleStream
//LongStream
//Sum
int sum = IntStream.of()
.sum();
System.out.println(sum);
//max() Optional : primitive
OptionalInt maxOptional = IntStream.of(1,3,4,5)
.max();
System.out.println(maxOptional.getAsInt());
//min() : Optional Primitive
OptionalInt minOptional = IntStream.of(1,2,3,4)
.min();
System.out.println(minOptional.getAsInt());
//average() OptionalDouble
OptionalDouble avgOptional = IntStream.of(1,2,3,4)
.average();
System.out.println(avgOptional.getAsDouble());
//summaryStatistics()
IntSummaryStatistics summaryStatistics = IntStream.of(1,2,34)
.summaryStatistics();
System.out.println(summaryStatistics);
}
}