Introduction to Programming电子书

Title Page

Copyright and Credits

Introduction to Programming

Dedication

Contributors

About the author

About the reviewers

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Why subscribe?

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Preface

Who this book is for

What this book covers

To get the most out of this book

Download the example code files

Download the color images

Conventions used

Get in touch

Reviews

Java Virtual Machine (JVM) on Your Computer

What is Java?

Basic terms

History and popularity

Principles

Java platforms, editions, versions, and technologies

Platforms and editions

Versions

Technologies

Java SE Development Kit (JDK) installation and configuration

Where to start

The page with Java installers

How to install

Main Java commands

The JVM execution command

The compilation command

Command jcmd and other commands

Exercise – JDK tools and utilities

Answer

Summary

Java Language Basics

The basic terms of Java programming

Byte code

Defects (bugs) and their severity and priority

Java program dependencies

Statements

Methods

Classes

The Main class and the main method

Classes and objects (instances)

Java classes

Java object (class instance)

Class (static) and object (instance) members

Private and public

Static members

Object (instance) members

Method overloading

Interface, implementation, and inheritance

Interface

Implementation

Inheritance

The java.lang.Object class

The equals() method

The hashCode() method

The getClass() method

The toString() method

The clone() method

The wait() and notify() methods

OOP concepts

Object/class

Encapsulation

Inheritance

Interface (abstraction)

Polymorphism

Exercise – Interface versus abstract class

Answer

Summary

Your Development Environment Setup

What is the development environment?

Java editor is your main tool

Source code compilation

Code sharing

Code and test execution

Setting the classpath

Manual setting

Searching on the classpath

IDE sets the classpath automatically

There are many IDEs out there

NetBeans

Eclipse

IntelliJ IDEA

Installing and configuring IntelliJ IDEA

Downloading and installing

Configuring IntelliJ IDEA

Exercise – Installing NetBeans IDE

Answer

Summary

Your First Java Project

What is a project?

Definition and origin of project

Project-related terms

A project's life cycle

Creating a project

Creating a project using a project wizard

Maven project configuration

Changing IDE settings at any time

Writing an application code

Java package declaration

Creating a package

Creating the MyApplication class

Building the application

Hiding some files and directories

Creating the SimpleMath class

Creating methods

Executing and unit testing an application

Executing the application using the IDE

Creating a unit test

Executing the unit test

How many unit tests are enough?

Exercise – JUnit @Before and @After annotations

Answer

Summary

Java Language Elements and Types

What are the Java language elements?

Input elements

Types

Comments

Identifiers and variables

Identifier

Variable

Variable declaration, definition, and initialization

Final variable (constant)

Reserved and restricted keywords

Reserved keywords

Restricted keywords

Separators

Semicolon ";"

Braces "{}"

Parentheses "()"

Brackets "[]"

Comma ","

Period "."

Ellipsis "..."

Colons "::"

At sign "@"

Primitive types and literals

The Boolean type

Integral types

Floating-point types

Default values of primitive types

Primitive type literals

Reference types and String

Class types

Interface types

Arrays

Default value of a reference type

Reference type literals

String immutability

Enum types

Passing reference type values as method parameters

Exercise – Variable declarations and initializations

Answer

Summary

Interfaces, Classes, and Object Construction

What is an API?

Java APIs

Command line APIs

HTTP-based APIs

Software component API

Interface and object factory as API

Interface

Object factory

Reading configuration file

Using the json-simple library

Using the json-api library

Unit test

Calculator API

Adding static methods to API

The API is complete

Overloading, overriding, and hiding

Interface method overloading

Interface method overriding

Interface static member hiding

Class member hiding

Instance method overriding

Instance method overloading

This, super, and constructors

Keyword this and its usage

Keyword super and its usage

Constructors

Final variable, final method, or final class

Final variable

Final method

Final class

Exercise – Restricting a class instantiation to a single shared instance

Answer

Summary

Packages and Accessibility (Visibility)

What is importing?

Structure of the .java file and packages

Single class import

Multiple classes import

Static import

Access modifiers

The accessibility of a top-level class or interface

Access to class or interface members

The constructor's accessibility is the same as any class member

Encapsulation

Data hiding and decoupling

Flexibility, maintainability, and refactoring

Reusability

Testability

Exercise – Shadowing

Answer

Summary

Object-Oriented Design (OOD) Principles

What is the purpose of design?

The project's feasibility

Requirement gathering and prototyping

High-level design

Detailed design

Coding

Testing

A roadmap to a good design

Encapsulating and coding to an interface

Taking advantage of polymorphism

Decoupling as much as you can

Preferring aggregation over inheritance

So many OOD principles and so little time

Exercise – Design patterns

Answer

Summary

Operators, Expressions, and Statements

What are the core elements of Java programming?

Operators

Arithmetic unary (+ -) and binary operators: + - * / %

Incrementing and decrementing unary operators: ++ --

Equality operators: == !=

Relational operators: < > <= >=

Logical operators: ! & |

Conditional operators: && || ? : (ternary)

Assignment operators (most popular): = += -= *= /= %=

Instance creation operator: new

Type comparison operator: instanceof

Preferring polymorphism over the instanceof operator

Field access or method invocation operator: .

Cast operator: (target type)

Expressions

Statements

Operator precedence and evaluation order of operands

Operator precedence

Evaluation order of operands

Widening and narrowing reference types

Widening

Narrowing

Widening and narrowing conversion of primitive types

Widening

Narrowing

Methods of primitive type conversion

Boxing and unboxing between primitive and reference types

Boxing

Unboxing

Method equals() of reference types

Using the implementation of the base class Object

Overriding the equals() method

Using the identification implemented in the parent class

The equals() method of the String class

The equals() method in wrapper classes of primitive types

Exercise – Naming the statements

Answer

Summary

Control Flow Statements

What is a control flow?

Selection statements

Iteration statements

Branching statements

Exception handling statements

Selection statements

if

if...else

if...else if-...-else

switch...case

Iteration statements

while

do...while

for

for enhanced

for with multiple initializers and expressions

Branching statements

Break and labeled break

Continue and labeled continue

return

Exception handling statements

throw

try...catch

Checked and unchecked (runtime) exceptions

throws

Custom exceptions

What is exception handling?

Some best practices of exception handling

finally

Assert requires JVM option -ea

Exercise – Infinite loop

Answer

Summary

JVM Processes and Garbage Collection

What are JVM processes?

Loading

Linking

Initialization

Instantiation

Execution

Garbage collection

Application termination

JVM architecture

Runtime data areas

Classloader

Execution engine

Threads

Extending the Thread class

What is daemon?

Running threads extending Thread

Implementing Runnable

Runing threads implementing Runnable

Extending Thread vs implementing Runnable

How to execute the main(String[]) method

Using IDE

Command line with classes on classpath

Command line with a .jar file on classpath

Command line with an executable .jar file

Garbage collection

Responsiveness, throughput, and stop-the-world

Object age and generations

When stop-the-world is unavoidable

Exercise – Monitoring JVM while running an application

Answer

Summary

Java Standard and External Libraries

What are standard and external libraries?

Java standard libraries

java.lang

java.util

java.time

java.io and java.nio

java.sql and javax.sql

java.net

java.math

java.awt, javax.swing, and javafx

Java external libraries

org.junit

org.mockito

org.apache.log4j and org.slf4j

org.apache.commons

org.apache.commons.io

org.apache.commons.lang and lang3

org.apache.commons.codec.binary

Exercise – Comparing String.indexOf() and StringUtils.indexOf()

Answer

Summary

Java Collections

What are collections?

The java.util package

Apache Commons collections

Collections vs arrays

Here is what we are going to discuss

List - ArrayList preserves order

Prefer variable type List

Why is it called ArrayList?

Adding elements

size(), isEmpty(), clear()

Iterate and stream

Add using generics

Add collection

Implementing equals() and hashCode()

Locating element

Retrieving elements

Removing elements

Replacing elements

Sorting String and numeral types

Sorting custom objects

Comparing with another collection

Converting to array

List implementations

Set - HashSet does not allow duplicates

Preferring variable type Set

Why is it called HashSet?

Adding elements

size(), isEmpty(), and clear()

Iterate and stream

Adding using generics

Adding collection

Implementing equals() and hashCode()

Locating element

Retrieving elements

Removing elements

Replacing elements

Sorting

Comparing with another collection

Converting to array

Set implementations

Map – HashMap stores/retrieves objects by key

Preferring variable type Map

Why is it called HashMap?

Adding and maybe replace

size(), isEmpty(), and clear()

Iterate and stream

Adding using generics

Adding another Map

Implementing equals() and hashCode()

Locating element

Retrieving elements

Removing elements

Replacing elements

Sorting

Comparing with another collection

Map implementations

Exercise – EnumSet methods

Answer

Summary

Managing Collections and Arrays

Managing collections

Initializing collections

Collection constructor

Instance initializer (double brace)

Static initialization block

Factory methods of()

Using other objects and streams

Immutable collections

Immutable versus unmodifiable

Immutable without methods of()

Methods add() and put() confusion

java.util.Collections class

Copy

Sort and equals()

Reverse and rotate

Search and equals()

Comparing two collections

Min and max elements

Add and replace elements

Shuffle and swap elements

Converting to a checked collection

Convert to a thread-safe collection

Convert to another collection type

Create enumeration and iterator

Class collections4.CollectionUtils

Manage arrays

Initialize arrays

Creation expression

Array initializer

Static initialization block

From collection

Other possible methods

Class java.util.Arrays

Class lang3.ArrayUtils

Exercise – Sort list of objects

Answer

Summary

Managing Objects, Strings, Time, and Random Numbers

Managing objects

Class java.util.Objects

equals() and deepEquals()

hash() and hashCode()

isNull() and nonNull()

requireNonNull()

checkIndex()

compare()

toString()

Class lang3.ObjectUtils

Managing strings

StringBuilder and StringBuffer

Class java.lang.String

Constructors

format()

replace()

compareTo()

valueOf(Objectj)

valueOf(primitive or char[])

copyValueOf(char[])

indexOf() and substring()

contains() and matches()

split(), concat(), and join()

startsWith() and endsWith()

equals() and equalsIgnoreCase()

contentEquals() and copyValueOf()

length(), isEmpty(), and hashCode()

trim(), toLowerCase(), and toUpperCase()

getBytes(), getChars(), and toCharArray()

Get code point by index or stream

Class lang3.StringUtils

Managing time

java.time.LocalDate

java.time.LocalTime

java.time.LocalDateTime

Period and Duration

Managing random numbers

Method java.lang.Math.random()

Class java.util.Random

Exercise – Objects.equals() result

Answer

Summary

Database Programming

What is Java Database Connectivity (JDBC)?

Connecting to the database

Closing the database connection

Structured Query Language (SQL)

Creating a database and its structure

CREATE and DROP the database and its user

CREATE, ALTER, and DROP table

Create, read, update, and delete (CRUD) data

INSERT statement

SELECT-statement

UPDATE-statement

DELETE-statement

Using the PreparedStatement class

Exercise – Selecting unique first names

Answer

Summary

Lambda Expressions and Functional Programming

Functional programming

What is a functional interface?

Ready-to-use standard functional interfaces

Function<T, R>

Consumer<T>

Supplier<T>

Predicate<T>

Other standard functional interfaces

Chaining standard functions

Chain two Function<T,R>

Chain two Consumer<T>

Chain two Predicate<T>

identity() and other default methods

Lambda expressions

What is a lambda expression?

Re-implementing functions

Lambda limitations

Effectively final local variable

The this keyword interpretation

Method references

Exercise – Using the method reference to create a new object

Answer

Summary

Streams and Pipelines

What is a stream?

Stream operations

Creating a stream

Stream interface

empty(), of(T t), ofNullable(T t)

iterate(Object, UnaryOperator)

concat(Stream a, Stream b)

generate(Supplier)

of(T... values)

The Stream.Builder interface

Other classes and interfaces

Intermediate operations

Filtering

Mapping

Sorting

Peeking

Terminal operations

Processing each element

Counting all elements

Matching all, any, or none

Finding any or first

Class Optional

Min and max

The toArray() operation

The reduce operation

The collect operation

Class collectors

Numeric stream interfaces

Creating a stream

range(), rangeClosed()

Intermediate operations

boxed() and mapToObj()

mapToInt(), mapToLong(), and mapToDouble()

flatMapToInt(), flatMapToLong(), and flatMapToDouble()

Terminal operations

sum() and average()

Parallel processing

Stateless and stateful operations

Sequential or parallel processing?

Exercise – Multiplying all the stream elements

Answer

Summary

Reactive Systems

How to process a lot of data quickly

Asynchronous

Sequential versus parallel streams

Using the CompletableFuture class

Non-blocking

The java.io versus java.nio package

Event loop, or run loop

Distributed

Scalable

Reactive

Responsive

Resilient

Elastic

Message-driven

Microservices

Vert.x basics

The HTTP server as a microservice

Periodic service as a microservice

The HTTP client as a microservice

Other microservices

Reactive systems

Message-driven system

Message consumer

Message sender

Message publisher

Reality check

Exercise – Creating io.reactivex.Observable

Answer

Summary

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