Streams - Beginning Java 8 Language Features - page 608

If you want to use the generate() method to generate an infinite stream in which the next element is generated
based on the value of the previous element, you will need to use a Supplier that stores the last generated element.
Note that a PrimeUtil object can act as a Supplier whose next() instance method remembers the last generated
prime number. The following snippet of code prints five prime numbers after skipping the first 100:
Stream.generate(new PrimeUtil()::next)
.skip(100)
.limit(5)
.forEach(System.out::println);
547
557
563
569
571
Java 8 has added many methods to the Random class in the java.util package to work with streams. Methods
like ints() , longs() , and doubles() return infinite IntStream , LongStream , and DoubleStream , respectively, which
contain random numbers of the int , long , and double types. The following snippet of code prints five random int
values from an IntStream returned from the ints() method of the Random class:
// Print five random integers
new Random().ints()
.limit(5)
.forEach(System.out::println);
-1147567659
285663603
-412283607
412487893
-22795557
You may get a different output every time you run the code. You can use the nextInt() method of the Random
class as the Supplier in the generate() method to achieve the same.
// Print five random integers
Stream.generate(new Random()::nextInt)
.limit(5)
.forEach(System.out::println);
If you want to work with only primitive values, you can use the generate() method of the primitive type stream
interfaces. For example, the following snippet of code prints five random integers using the generate() static method
of the IntStream interface:
IntStream.generate(new Random()::nextInt)
.limit(5)
.forEach(System.out::println);