Java Reference
In-Depth Information
tures (the ability to include
default
and
static
methods) and discussed the concept of
functional interfaces.
This chapter presents many examples of functional programming, often showing sim-
pler ways to implement tasks that you programmed in earlier chapters (Fig. 17.1)
Pre-Java-SE-8 topics
Corresponding Java SE 8 discussions and examples
Chapter 7, Arrays and ArrayLists
Sections 17.3-17.4 introduce basic lambda and streams capabili-
ties that process one-dimensional arrays.
Chapter 10, Object-Oriented
Programming: Polymorphism
and Interfaces
Section 10.10 introduced the new Java SE 8 interface features
(
default
methods,
static
methods and the concept of func-
tional interfaces) that support functional programming.
Chapter 12, GUI Components:
Part 1
Section 17.9 shows how to use a lambda to implement a Swing
event-listener functional interface.
Chapter 14, Strings, Characters
and Regular Expressions
Section 17.5 shows how to use lambdas and streams to process
collections of
String
objects.
Chapter 15, Files, Streams and
Object Serialization
Section 17.7 shows how to use lambdas and streams to process
lines of text from a file.
Chapter 22, GUI Components:
Part 2
Discusses using lambdas to implement Swing event-listener
functional interfaces.
Chapter 23, Concurrency
Shows that functional programs are easier to parallelize so that they
can take advantage of multi-core architectures to enhance perfor-
mance. Demonstrates parallel stream processing. Shows that
Arrays
method
parallelSort
improves performance on multi-
core architectures when sorting large arrays.
Chapter 25, JavaFX GUI: Part 1
Discusses using lambdas to implement JavaFX event-listener
functional interfaces.
Fig. 17.1
|
Java SE 8 lambdas and streams discussions and examples.
In the preceding chapters, you learned various procedural, object-oriented and generic
programming techniques. Though you often used Java library classes and interfaces to per-
form various tasks, you typically determine
what
you want to accomplish in a task then
specify precisely
how
to accomplish it. For example, let's assume that
what
you'd like to
accomplish is to sum the elements of an array named
values
(the
data source
). You might
use the following code:
int
sum =
0
;
for
(
int
counter =
0
; counter < values.length; counter++)
sum += values[counter];
This loop specifies
how
we'd like to add each array element's value to the
sum
—with a
for
repetition statement that processes each element one at a time, adding each element's value
to the
sum
. This iteration technique is known as
external iteration
(because you specify
how to iterate, not the library) and requires you to access the elements sequentially from
