Job Ready Java

HAYTHEM BALTI, PhD, is Director of Curriculum at Wiley’s Software Guild and mthree. He has created courses used by thousands of Software Guild Students in Java, Python, Go, and other development and data science competencies. He earned his doctorate in Computer Engineering and Computer Science from the University of Louisville.ALAN GALLOWAY is Director of Instruction at Wiley’s Software Guild and mthree. H:e supervises a team of instructors who deliver large-scale training programs in technology.

• About the Authors vAbout the Technical Writer viiAbout the Technical Editors viiAcknowledgments ixIntroduction xxvPart I: Getting Set Up 1Lesson 1: Installing Java 2The Java Universe 3The Java Development Kit 3The Java Virtual Machine 4The Java Runtime Environment 5Installing OpenJDK 5Installing OpenJDK on Microsoft Windows 6Checking for an Existing JDK on Windows 6Installing OpenJDK 7Verifying the Installation 10Installing OpenJDK on macOS 13Checking for an Existing JDK on macOS 13Installing OpenJDK 13Verifying the Installation 17Creating Your First Java Program 17Writing the Program 18Compiling and Running the Program 19Dealing with Syntax Errors 21Using the Compiler and Java Virtual Machine 22Summary 22Lesson 2: Installing a Development Environment: NetBeans 24Getting Started 25Understanding the Value of an IDE 25Using the Source Code Editor 25Using the Build Automation Tools 26Using the Debugger 26Installing NetBeans 27Using an Installer 27Installing on Windows 28Installing on macOS 32Installing Binaries 37Installing Binaries on Windows 40Adding the JDK 42Running NetBeans 44Summary 45Lesson 3: Using an Integrated Development Environment 46Using an IDE 47Creating a New Project 48Coding the “Hello, World!” Program 53Compiling the Code in NetBeans 57Running the Program 59Using the Debugging Tools 60Compilation and Syntax Errors 61Runtime and Logic Errors 63Understanding Source Control 67Summary 69Part II: Basics of Object Oriented Programming 70Lesson 4: Using Program Statements and Variables 71Approach 72Concepts 73Computers 73Data vs. Information 73Programs and Programming 74Models and Metaphors 74Objects 74Specifications 75Syntax vs. Semantics 75Language Building Blocks 75Comments 75Single-Line Comments 76Multiline Comments 76Doc Comments 77Using Comments 78Identifiers 79Data Types 80Statically Typed Languages 81Type Conversion 81Literals 82Variables 82Constants 84Operators and Expressions 84Three Flavors of Operators 85Operator Precedence 88Pulling It All Together: Mathematical Expressions and Operators 89Summary 93Exercises 93Exercise 1: ABeginning.java 94Exercise 2: ProjectGutenberg.java 95Exercise 3: CommentingCode.java 97Exercise 4: AllTheMath.java 98Exercise 5: BucketsOfFun.java 100Lesson 5: Collecting and Parsing Input from the User 103Console Input and Output 104Adder Version 1 104Adder Version 2 106Declaring and Initializing Our Variables 106Setting Up a Scanner Object 106Understanding the Command Line 107Getting the Values from the User 108Going from Strings to Integers 108Adding the Numbers Together 109Using Loops to Gather User Input 111Parsing Data 112Dealing with Bad Numbers: NumberFormatException 113Scanner Problems 115Summary 121Exercises 121Exercise 1: Quest for the User Input 121Exercise 2: Don’t Forget to Store It 123Exercise 3: Passing the Turing Test 124Exercise 4: Healthy Hearts 125Exercise 5: Mini Mad Libs 126Lesson 6: Pulling It All Together: Building a Useful Program 127Planning the Program 128Identifying the Variables 128Planning the Steps 128Creating the Code 129Declaring the Variables 129Getting Input 130Converting the Strings 131Calculating the Area and Perimeter 132Calculating the Cost 133Displaying the Results 133Running the Program 135Summary 135Exercises 136Exercise 1: Mapping Instructions to Code 136Exercise 2: Adding Prompts for Costs 136Exercise 3: Adding Multiple Windows 136Exercise 4: Adding Validation 137Lesson 7: Controlling Program Flow 138What Can Our Code Do? 139Decisions and Boolean Expressions 139if Statements 139if-else Statements 142Chaining if-else Statements 144Evaluating Multiple Conditions 146Conditional-And and Conditional-Or Operators 147Exclusive-Or 149Ternary or Conditional Operator 150switch Statement 151Falling Through with a switch Statement 153Comparing for Equal Strings 155Summary 158Exercises 159Exercise 1: What Month is It? 159Exercise 2: Guess Me 159Exercise 3: Birthstones 160Exercise 4: Trivia Night 161Exercise 5: Space Rustlers 162Exercise 6: Picky Eater 163Exercise 7: Field Day 165Lesson 8: Looping Program Flow 167Loops 167Using while Loops 168Initializing the while Loop 171Incrementing the while Loop 171Breaking a Loop 172Using do-while Loops 174Making do-while Shine 176Using for Loops 179Initializing the for Loop 181Terminating the for Loop 181Incrementing a for Loop 181Summary 184Exercises 184Exercise 1: Surfacing in BewareTheKraken.java 185Exercise 2: Do or Do Not 185Exercise 3: Guess Me Finally 186Exercise 4: for and Twenty Blackbirds 187Exercise 5: Spring Forward, Fall Back 188Exercise 6: for Times 189Exercise 7: for Times for 189Exercise 8: Nesting for Loops 190Exercise 9: Traditional Fizz Buzz 191Lesson 9: Understanding Flowcharts and Algorithms 193Flowchart Basics 194Sequences 194Branches 195Loops 196Flowcharting 197Flowchart Example 197Summary 198Exercises 200Exercise 1: A Guessing Game 200A Possible Flowcharting Solution 201The Guessing Game Flowchart 201The Guessing Game Code 203Lesson 10: Adding Randomness to Your Programs 207Initializing the Random Object 208Including the Random Class 208Seeding Random Numbers 208Generating Random Integers 209Generating Random Doubles 210Revisiting the Number Guessing Game 212Other Random Options 215Summary 215Exercises 215Exercise 1: A Little Chaos 216Exercise 2: Opinionator—Making Random Choices 217Exercise 3: High Roller 219Exercise 4: Coin Flipper 220Exercise 5: Guess Me More 220Exercise 6: Fortune Cookie 221Lesson 11: Debugging 222Creating a File to Debug 222Setting Breakpoints 224Stepping through Code 226Running the Debugger 226Examining Variables 229The Console and the Debugger 232Summary 234Exercises 234Exercise 1: Odd Odd Numbers 234Exercise 2: A Simple Question of If 235Lesson 12: Adding Methods 237Why Methods? 238Defining Methods 238Method Signature 239Method Naming Conventions 239Return Values 240Using Return Values 241Input Parameters 242Matching Number of Parameters 244Matching Parameter Types 245Passing Parameters 246Method Forms 248No Return Value, No Parameters 248Return Value, No Parameters 248No Return Value, One or More Parameters 249Return Value, One or More Parameters 249The staticKeyword 249Pulling It All Together 250Identifying the Similarities 252Identifying the Differences 252Creating the Method 252Setting the Name 252Determining Parameters 253Setting a Return Type 253Our Basic Definition 253Our Method Body 254Using the Method 255Scope 257Debugging and Step Into 259Setting a Breakpoint in a Method 260Stepping into Code 262Debugging and Scope 265Summary 265Exercises 265Exercise 1: Method to the Madness 266Exercise 2: Return to Sender 267Exercise 3: MatchWork 268Exercise 4: Barely Controlled Chaos 269Lesson 13: Organizing with Arrays 272What is an Array? 273Types of Arrays 274Element vs. Index 275Declaring Arrays 276Single-Dimensional Arrays 276Rectangular Arrays 276Jagged Arrays 277Initializing Arrays 277Initializing a Single-Dimensional Array 278Initializing a Rectangular Array 279Initializing a Jagged Array 280Accessing Array Elements 281Accessing Elements in a Single-Dimensional Array 281Accessing Elements in a Multidimensional Array 283Accessing Elements in a Jagged Array 284Iterating through Arrays 284Iterating through Multidimensional and Jagged Arrays 286Sum the Elements of an Array 288Looping Back to Front, with a Twist 289Printing Pairs of Elements 290Changing the Size of an Array 291Dealing with Errors 293Summary 293Exercises 294Exercise 1: A Rainbow 294Exercise 2: Still Positive 295Exercise 3: Fruit Basket 296Exercise 4: Simple Combination 297Exercise 5: Hidden Nuts 297Exercise 6: Summative Sums 298Part III: Fundamentals of Classes and Objects 299Lesson 14: Object-Oriented Concepts 300Abstraction 301Object Orientation 301Types 302Public Interface/Private Implementation 302Encapsulation and Data Hiding 303Single Responsibility Principle and Cohesion 303Delegation 304Summary 304Lesson 15: Creating Classes and Types 305Creating New Types 305Classes vs. Objects 307Properties, Accessors, and Mutators 307Dot Operator 308this Keyword 309Methods/Behaviors 309Constructors 309Object Instantiation and Method Invocation 311Static Keyword 312Static and the Main Method 313Static and Constant Values 313Static and Utility Methods 314Pulling It All Together 315Creating a New Class 316Going Static 320When to Go Static 323Existing Static Methods 325Summary 325Exercises 326Exercise 1: Class Modeling 327Exercise 2: Refactoring 328Exercise 3: A Multiclass Problem 330Lesson 16: Managing Storage and Memory 331Programs and Memory 331The Stack 332The Heap 334Garbage Collection 338Reference and Null Values 339Summary 341Lesson 17: Exploring Interfaces, Composition, and Inheritance 342How Do These Tools Help? 343Interfaces 344Composition and Inheritance 345Composition 345Inheritance 346Using Interfaces, Composition, and Inheritance 346Summary 347Lesson 18: Diving into Interfaces 348What is an Interface? 349Declaring an Interface 349Implementing an Interface 350Interface Restrictions 352Implementing Multiple Interfaces 352Extending an Interface 354Interfaces and Polymorphism 356Summary 357Lesson 19: Diving into Composition 358What is Composition? 359Book without Composition 359Book with Composition 360Summary 362Exercises 362Exercise 1: Classroom Composition 362Exercise 2: Cookbook 363Lesson 20: Diving into Inheritance 365Everything Extends Object 366Terminology 366Access Control 367Inheritance 368Code Reuse through Inheritance 371Method Overloading 371Method Overriding 373Constructors 375Polymorphism 380Calling Methods Polymorphically 382Abstract Base Classes 383Summary 383Exercises 383Exercise 1: Working with Shape 384Lesson 21: Understanding Collections 385Collections in Java 385Javadoc 386Collections Framework Structure 387Interface vs. Implementation 389Iterator 390Commonly Used Interfaces in the Collections Framework 390Quick Look at List 390ArrayList 390Stack 391Quick Look at Set 391HashSet 391TreeSet 392Quick Look at Map 392HashMap 392TreeMap 392Summary 393Lesson 22: Introduction to Lists 394List 394Types of Lists 395ArrayList 395LinkedList 395Stack 397Understanding Generics 397Using Lists 398Instantiating a List 398Adding Items to a List 401Accessing Items in a List 402Inserting Items into a List 403Removing Items from a List 403Enhanced Approaches to Access List Items 405The Enhanced for Loop and Lists 406Visiting Each Element: Iterators 407Creating an Iterator 407Using the Iterator 408Summary 410Exercises 410Exercise 1: Three Threes 410Exercise 2: Mixed-Up Animals 411Lesson 23: Exploring Maps 412Map Interface 412HashMap 413Creating and Adding Entries to a Map 413Instantiating a Map 413Adding Data to a Map 414Manipulating with Entries in a Map 415Looking Up Values in a Map 415Replacing Data in a Map 417Removing Values from a Map 417Getting Keys and Listing Mapped Values in a Map 417Listing All the Keys 417Listing All the Values Key by Key 420Listing All the Values: Value Collection 421Summary 423Exercises 423Exercise 1: State Capitals 423Exercise 2: A Reusable User I/O Class 424Exercise 3: Student Quiz Scores 427Lesson 24: Using Simple File Input and Output 429Data Storage and Representation 430File Format, Marshaling, and Unmarshaling 431Student Class 432File Format Example 433Marshaling and Unmarshaling Approach 433Simple File I/O 434Writing to a File 435Exceptions 436The OutFile.txt File 437Reading from a File 438Summary 440Exercises 440Exercise 1: Creating State Capitals 441Exercise 2: Hashing the State Capitals 442Exercise 3: A State Guessing Game 442Exercise 4: Objectifying States 443Lesson 25: Applying Application Design 446CRUD Applications 447Using a Tiered Design 448The Basic Tiers 448The Model-View-Controller Pattern 448Packages 449Software Development Lifecycle Overview 450Waterfall 450Iterative Development 451Agile Development 451Project Lifecycle 452Phase 1: Inception 452Phase 2: Elaboration 452Phase 3: Construction 453Phase 4: Transition 453Iterations 453Summary 454Lesson 26: Handling Exceptions 455Exception Handling 456Catch or Specify Requirement 459Exception Types 459Handling (Catching) Exceptions 459try Block 459catch Block 461finally Block 462Specifying and Throwing Exceptions 464Exception Translation and Encapsulation 465Summary 466Exercises 466Exercise 1: Keep On Asking 466Exercise 2: Arrays Gone Bad 466Exercise 3: Exiting Gracefully 468Lesson 27: Pulling It All Together: Building the Class Roster App 469Application Requirements and Use Cases 470Understanding theApplication Structure 470Interface Relationships 471Composition Relationships 472Inheritance Relationships 472Classes and Interfaces in Our Application 472MVC Rules of the Game 473Construction Approach 473Setting Up the Class Roster Application Shell 474Creating the Menu System 477UserIO and UserIOConsoleImpl 478ClassRosterController 482App 483ClassRosterView 484ClassRosterController 485Adding a Student Use Case 487Student (DTO) 487ClassRosterDao and ClassRoster-DaoFileImpl 488ClassRosterDao 488ClassRosterDaoFileImpl 490ClassRosterView 491ClassRosterController 493Viewing All Students Use Case 494ClassRosterDaoFileImpl 494ClassRosterView 495ClassRosterController 496Getting a Student Use Case 497ClassRosterDaoFileImpl 498ClassRosterView 498ClassRosterController 499Removing a Student Use Case 501ClassRosterDaoFileImpl 501ClassRosterView 501ClassRosterController 502Handling Unknown Command and Exiting 504ClassRosterView 504ClassRosterController 504Working with Dependency Injection 506Implementation 507ClassRosterController 507ClassRosterView 508App 508Handling Application Exceptions 509ClassRosterDaoException 509Adding File Persistence 512ClassRosterDaoFileImpl 512Constants 512unmarshalStudent 513loadRoster 514marshalStudent 516writeRoster 517addStudent 518getAllStudents 519getStudent 520removeStudent 520ClassRosterDao 521ClassRosterView 522ClassRosterController 522Create roster.txt 525Summary 527Exercises 527Exercise 1: DVD Library Update 527Exercise 2: Electronic Address Book 528Part IV: Intermediate Java 531Lesson 28: Exploring the Service Layer 532The Role of the Service Layer 532Service Layer Exceptions 534Service Layer API Design 534New Business Rules 534Create a Student 535Define the Method Signature 535Define the Return Type 535Define the Errors That Might Occur in This Method 535Service Layer Methods for Getting Students 536Get All Students 536Get a Single Student 537Remove a Student 537Summary 537Lesson 29: Pulling It All Together: Coding the Class Roster Service Layer 538Create a Service Layer Interface 539Create New Exceptions 542ClassRosterDuplicateIdException 542ClassRosterDataValidation Exception 543Refactor/Rename ClassRoster-DaoException 543Create the Service Layer Implementation 546Constructor and DAO Member 547Validating Student Data 547Create Student 548Get All Students 549Get One Student 549Remove Student 550Modify the Controller 550Replace Member Field 551Modify Constructor 551Replace Calls to DAO Methods with Calls to the Service Layer Method 551Modify the App 553Add the Audit Log Feature 554Audit DAO Interface and Implementation 554Modify the Service Layer 556Add Member Field 556Modify the Constructor 556Modify createStudent 556Modify removeStudent 557Modify App 558Summary 559Lesson 30: Doing Unit Testing 560Unit Testing 561Types of Unit Testing 561Black-Box vs. Glass-Box Testing 562Stateful vs. Stateless Components 562Test-Driven Development and Red/Green/Refactor 562Test Stubs 563JUnit 563Test Setup and Teardown 563Annotations 564Asserts 564Given/When/Then 564Stateless Unit Testing 565What Makes a Good Unit Test? 565Designing a Test Plan 565Happy Llama Test Plan 567Implementing Unit Tests 568Creating the Test Class 568Writing Happy Llama Tests 569Running JUnit Tests 571Summary 575Lesson 31: Testing Stateful Code 577Unit Testing Stateful Code 578Separating Production and Test Data 579Adding hashCode and equals to Student 580Adding toString to Student 582Creating the Test Class 583The Set Up and Tear Down Methods 584Arrange/Act/Assert for Stateful Code 585Class Roster DAO Test Design 586Add Student 586Get Student 588ClassRosterDaoTest: Adding and Getting a Student 589Get All Students 590ClassRosterDaoTest: Adding and Getting All Students 590Remove Student 592ClassRosterDaoTest: Adding and Removing Students 592Unit Testing the Service Layer 594Planning the Test Design 595Creating the Test Class 595Creating the DAO Stubs 596ClassRosterAuditDaoStubImpl 597ClassRosterDaoStubImpl 597Test Setup 599Test Implementation 600testCreateValidStudent 600testCreateStudentDuplicateId 601testCreateStudentInvalidData 602testGetAllStudents 603testGetStudent 603testRemoveStudent 604Summary 605Exercises 605Exercise 1: Testing the Address Book App 605Exercise 2: Testing the DVD Library 606Lesson 32: Including Magic Numbers and Enums 607Magic Numbers 608Enums 608Creating Enums for Fixed Constants 609Using Enums 609Getting Values from an Enum 611Enum Members 612Summary 616Exercises 616Exercise 1: How Many Days until Friday? 617Exercise 2: Playing Cards 617Lesson 33: Manipulating Dates and Times 618ISO Calendar 619Human Time and Machine Time 619Local and Zoned Classes 619Periods and Duration 620Working with LocalDate Objects 620Creating LocalDates 620Converting Dates to and from Strings 622Formatting Dates 623Using Localization 625Getting the Time with LocalDateTime 626Working with Date Calculations 628Calculating Dates in the Future and Past 628Calculating the Time between Two Dates 630Working with Legacy Dates 632Converting Date Objects 632Converting a GregorianCalendar Object 633Summary 635Exercises 635Exercise 1: Birthday Calculator 635Exercise 2: It’s The End of the World as We Know It 636Exercise 3: Tracking Your Time 636Lesson 34: Using the BigDecimal Class 638Exploring BigDecimal 639Constructing BigDecimals 639Understanding Scale 641Understanding Rounding Modes 641Working with BigDecimal 642Setting Scale 642Setting Scale without Rounding Mode 643Rounding BigDecimals 643Doing Calculations with BigDecimals 645Dividing BigDecimals 646Summary 648Exercises 648Exercise 1: Interest Calculator 648Exercise 2: Car Lot Service Layer 649Lesson 35: Working with Lambdas and Streams 653Using Aggregate Operations 654Understanding Pipelines and Streams 654Streams vs. Iteration 655Exploring Lambdas 655Working with Stream and Lambda Syntax 655The forEach() Stream Method 656The filter Stream Method 660The map Stream Method 661The collect Stream Method 663Further Syntax 664Summary 665Exercises 665Exercise 1: Only the Young 665Exercise 2: DVD Library Update 666Part V: Advanced Java 667Lesson 36: Working with the Spring Framework 668Dependency Injection and Programming to Interfaces 669Why Spring? 670Understanding the Spring Approach 670Plain Old Java Objects 671Templates 671Pulling It All Together: Spring DI in Action 673Spring DI with XML 674XML Configuration File 675Update the App Class 676Spring DI with Annotations 677Class Annotations 678Summary 681Lesson 37: Introducing Maven 682What is Maven? 683Project Object Model 683Project Identification 685Dependencies 685Build Settings 686Dependency Management 686Maven Lifecycle 687Summary 687Lesson 38: Pulling It All Together: Building the Class Roster with Spring 689Include the Spring Libraries 690How Do I Know What My Dependency Entry Should Be? 691Add Spring Configuration Files 692Convert the App Class to Use Spring 693Defining Beans 694Modifying the App Class 696Convert the Unit Tests to Use Spring 697Defining Beans 698Modifying the Test Class Constructor 699Exception Conditions 700Summary 701Exercises 701Exercise 1: DVD Library 701Part VI: Appendices 702Appendix A: Code Checklist 703Functionality 703Style 703Appendix B: Java concepts Study List 705Variables 705Methods 705Arrays 706Making Decisions 706Loops 706Java/JVM 706Objects 707Interfaces 708Inheritance 708N-Tier Design 708Collections 709Exceptions 709Lambdas/Streams 709Spring Core 709Appendix C: Agile Approach Checklist for Console CRUD Applications 710Assumptions 710Requirement Steps 711Design Steps 711Construction Steps 712Index 714