Streams - Beginning Java 8 Language Features - page 603

The accept() and add() methods add elements to the stream being built. You might wonder about the existence of
two methods in the builder to add elements. The Stream.Builder<T> interface inherits from the Consumer<T> interface,
and therefore it inherits the accept() method from the Consumer<T> interface. You can pass a builder's instance to a
method that accepts a consumer and the method can add elements to the builder using the accept method.
The add() method returns the reference to the builder that makes it suitable for adding multiple elements using
method chaining. Once you are done adding elements, call the build() method to create the stream. You cannot
add elements to the stream after you call the build() method; doing so results in an IllegalStateException runtime
exception. The following snippet of code uses the builder pattern to create a stream of four strings:

Stream<String> stream = Stream.<String>builder()
.add("Ken")
.add("Jeff")
.add("Chris")
.add("Ellen")
.build();

Note that the code specifies the type parameter as String when it obtains the builder Stream. <String> builder() .
The compiler fails to infer the type parameter if you do not specify it. If you obtain the builder separately, the compiler
will infer the type as String , as shown:

// Obtain a builder
Stream.Builder<String> builder = Stream.builder();

// Add elements and build the stream
Stream<String> stream = builder.add("Ken")
.add("Jeff")
.add("Chris")
.add("Ellen")
.build();

The IntStream interfaces contain two static methods:
•

IntStream range(int start, int end)

IntStream rangeClosed(int start, int end) .
They produce an IntStream that contains ordered integers between the specified start and end . The specified
end is exclusive in the range() method whereas it is inclusive in the rangeClosed() method. The following snippet of
code uses both methods to create an IntStream having integers 1, 2, 3, 4, and 5 as their elements:

•

// Create an IntStream containing 1, 2, 3, 4, and 5
IntStream oneToFive = IntStream.range(1, 6);
// Create an IntStream containing 1, 2, 3, 4, and 5
IntStream oneToFive = IntStream.rangeClosed(1, 5);

Like the IntStream interface, the LongStream class also contains range() 0and rangeClosed() methods that
takes arguments of type long and return a LongStream .