Java Programming Exercises. Volume One: Language Fundamentals and Core Concepts

Cover....1 Half Title....2 Title Page....4 Copyright Page....5 Table of Contents....6 About the Author....16 Introduction....18 Previous Knowledge and Target Audience....18 Working with This Book....19 The Suggested Solutions....19 Use of This Book....20 Required Software....20 Used Java Version in the Book....21 JVM....21 Development Environment....21 Conventions....21 Helping Captain CiaoCiao and Bonny Brain....22 1 Introduction to the Java Ecosystem....23 Bytecode and JVM....23 Porting Java Programs....23 Tools for Java Developers....24 Get to Know Error Messages of the IDE....24 Suggested Solutions....25 Porting Java Programs....25 Get to Know Error Messages of the IDE....25 2 Imperative Programming....26 Screen Output....26 Learn about the SVG Specification....26 Write an SVG Circle on the Console....27 Variables and Data Types....28 Access Variables and Output Their Assignments....29 Quiz: Value Ranges....29 Quiz: Does This Add Up?....29 Generate Random Circles....30 Quiz: Dazed and Confused....31 Process User Input....31 Expressions, Operands, and Operators....31 Quiz: Check In-Between....31 Check If Loot Can Be Shared Fairly....32 Do Two Numbers Share the Same Digit?....32 Convert Currency Amount to Coins....32 One Bottle of Rum, Ten Bottles of Rum....33 Quiz: The Zero Effect....34 Control Flow....35 Payday....35 Quiz: Wrong Branching....35 Convert Liters....36 Create SVG Circles with Random Colors....36 Quiz: To Which Block Does the Else Belong?....37 Quiz: Recognize Negative Days and Hours....37 Evaluate Input Strings for Approval....37 Rewrite Switch Statement to Switch Expression....38 Loops....38 Create Rotated SVG Rectangles....38 Create SVG-Pearl-Chain....39 Sum Numbers from the Command Line....40 Go through a Mathematical Phenomenon....41 Quiz: How Many Stars?....41 Calculate Products for Faculties....42 Determine If a Number Is Formed by Factorial....42 Find the Smallest and Largest Digit of a Number....43 Quiz: Not Like This from 1 to 100....44 A Flag in the Wind through Nested Loops....45 Output Simple Chessboard....45 It’s Christmastime: Displaying Trees with Ornaments....46 Draw Fishy Stitching Motifs....47 Trying Instead of Thinking....48 Get the Number of Digits of a Number....49 Methods....50 Drawing Hearts....50 Implement Overloaded Line Methods....51 Standing Straight....51 Create a Multiplication Table....52 Cistercian Numerals Script....53 Quiz: What Does Ding-Dong Do? (Recursion)....54 Quiz: Repdigit (Recursion)....54 Calculate Collatz Sequence (Recursion)....55 Ancient Egyptian Multiplication (Recursion)....55 Suggested Solutions....57 Write an SVG Circle on the Console....57 Access Variables and Output Their Assignments....58 Quiz: Value Ranges....59 Quiz: Does This Add Up?....60 Generate Random Circles....60 Quiz: Dazed and Confused....61 Process User Input....61 Quiz: Check In-Between....61 Check If Loot Can Be Shared Fairly....62 Do Two Numbers Share the Same Digit?....62 Convert Currency Amount to Coins....63 One Bottle of Rum, Ten Bottles of Rum....64 Quiz: The Zero Effect....64 Payday....64 Quiz: Wrong Branching....65 Convert Liters....65 Create SVG Circles with Random Colors....66 Quiz: To Which Block Does the Else Belong?....67 Quiz: Recognize Negative Days and Hours....67 Evaluate Input Strings for Approval....68 Rewrite Switch Statement to Switch Expression....69 Create Rotated SVG Rectangles....69 Create SVG-Pearl-Chain....70 Sum Numbers from the Command Line....70 Go through a Mathematical Phenomenon....71 Quiz: How Many Stars?....72 Calculate Products for Faculties....72 Determine If a Number Is Formed by Factorial....74 Find the Smallest and Largest Digit of a Number....75 Quiz: Not Like This from 1 to 100....75 A Flag in the Wind through Nested Loops....76 Output Simple Chessboard....77 It’s Christmastime: Displaying Trees with Ornaments....77 Draw Fishy Stitching Motifs....78 Trying Instead of Thinking....79 Get the Number of Digits of a Number....80 Drawing Hearts....82 Implement Overloaded Line Methods....82 Standing Straight....83 Create a Multiplication Table....85 Cistercian Numerals Script....86 Quiz: What Does Ding-Dong Do? (Recursion)....89 Quiz: Repdigit (Recursion)....89 Calculate Collatz Sequence (Recursion)....90 Ancient Egyptian Multiplication (Recursion)....92 3 Classes, Objects, and Packages....95 Creating Objects....95 Draw Polygons....95 Working with References....97 Quiz: The Short Life of Points....97 Build Triangles....97 Quiz: == vs. equals(…)....98 Quiz: Protect against NullPointerException....98 Suggested Solutions....99 Draw Polygons....99 Quiz: The Short Life of Points....100 Build Triangles....100 Quiz: == vs. equals(…)....101 Quiz: Protect against NullPointerException....101 Note....102 4 Arrays....103 Everything Has a Type....103 Quiz: Array Types....103 One-Dimensional Arrays....104 Loop Arrays and Output Wind Speed, Wind Direction....104 Detect Continuous Revenue Growth....105 Array of Points....105 Search Consecutive Strings and Determine If Salty Snook Is Coming....106 Reverse an Array....106 Find the Nearest Cinema....107 Raid the Candy Store and Share Fairly....107 Enhanced for Loop....108 Numbers Well Shuffled....109 Draw Mountains....110 Two- and Multidimensional Arrays....111 Check Mini-Sudoku for Valid Solution....111 Enlarge Image....112 Variable Argument Lists....113 Create SVG Polygons with a Variable Number of Coordinates....113 Check for Approval....114 Help, Tetraphobia! Put All Fours Last....114 The Utility Class Arrays....115 Quiz: Copy Arrays....115 Quiz: Compare Arrays....115 Suggested Solutions....116 Quiz: Array Types....116 Loop Arrays and Output Wind Speed, Wind Direction....116 Reverse an Array....117 Array of Points....118 Search Consecutive Strings and Determine if Salty Snook is Coming....119 Reverse an Array....120 Find the Nearest Cinema....121 Raid the Candy Store and Share Fairly....122 Draw Mountains....123 Check Mini-Sudoku for Valid Solution....124 Enlarge Image....126 Create SVG Polygons with Variable Number of Coordinates....126 Check for Approval....127 Help, Tetraphobia! Put All Fours Last....128 Quiz: Copy Arrays....129 Quiz: Compare Arrays....129 5 Character and String Processing....131 The String Class and Its Members....131 Quiz: Is String a Built-In Keyword?....131 Building HTML Elements with Simple Concatenation....131 Check Safe Transmission by Doubling Characters....132 Swap Y and Z....133 Give Defiant Answers....134 Quiz: String Comparisons with == and Equals(…)....134 Quiz: Is Equals(…) Symmetric?....135 Test Strings for Palindrome Property....135 Check if Captain CiaoCiao is in the Middle....136 Find the Shortest Name in the Array....137 Count String Occurrences....137 Determine the Larger Crew Size....138 Build Diamonds....139 Check for a Good Password....140 Bake Peanut Butter Cookies....140 Calculate Sum of Digits....141 Decolumnize Texts....142 Draw a Meadow with Favorite Flowers....143 Detect Repetitions....145 Constrain Line Boundaries and Wrap Lines....145 Quiz: How Many String Objects?....146 Test If the Fruit Is Wrapped in Chocolate....146 From Top to Bottom, from Left to Right....147 Dynamic Strings with StringBuilder....148 Fill Strings....148 Practicing the Alphabet with a Parrot....149 Quiz: Lightly Attached....150 Convert Number to Textual Unary Encoding....150 Lose Weight by Moving Digits....151 Remove Vowels....152 Don’t Shoot the Messenger....153 Compress Repeated Spaces....154 Insert and Remove Crackles and Pops....154 Split CamelCase Strings....155 Underline Words....155 Implement Caesar Encryption....155 Suggested Solutions....157 Quiz: Is String a Built-In Keyword?....157 Building HTML Elements with Simple Concatenation....157 Check Safe Transmission by Doubling Characters....157 Swap Y and Z....158 Give Defiant Answers....160 Quiz: String Comparisons with == and Equals(…)....160 Quiz: Is Equals(…) Symmetric?....160 Test Strings for Palindrome Property....161 Check if Captain CiaoCiao is in the Middle....163 Find the Shortest Name in the Array....163 Count String Occurrences....164 Determine the Larger Crew Size....165 Build Diamonds....166 Check for a Good Password....168 Bake Peanut Butter Cookies....169 Calculate Sum of Digits....170 Decolumnize Texts....171 Draw a Meadow with Favorite Flowers....173 Detect Repetitions....175 Constrain Line Boundaries and Wrap Lines....176 Quiz: How Many String Objects?....177 Test if the Fruit is Wrapped in Chocolate....177 From Top to Bottom, from Left to Right....178 Fill Strings....179 Practicing the Alphabet with a Parrot....180 Quiz: Lightly Attached....181 Convert Number to Textual Unary Encoding....182 Lose Weight by Moving Digits....183 Remove Vowels....184 Don’t Shoot the Messenger....186 Compress Repeated Spaces....187 Insert and Remove Crackles and Pops....188 Split CamelCase Strings....189 Underline Words....190 Implement Caesar Encryption....191 6 Writing Your Own Classes....193 Class Declaration and Object Properties....194 Declare Radio with Instance Variables and a Main Program....194 Implementing Methods of a Radio....194 Private Parts: Make Instance Variables Private....195 Create Setters and Getters....195 Static Variables Methods....195 Convert Station Names to Frequencies....195 Write Log Output with a Tracer Class....196 Quiz: Nothing Stolen....197 Simple Enumerations....198 Give Radio an AM–FM Modulation....198 Set Valid Start and End Frequency for Modulation....198 Constructors....198 Writing Radio Constructors....199 Implement Copy Constructor....199 Realize Factory Methods....199 Associations....200 Connect Monitor Tube with TV....200 Quiz: Association, Composition, and Aggregation....201 Add Radios with a 1:n Association to the Ship....201 Inheritance....202 Introduce Abstraction into Electrical Devices via Inheritance....202 Quiz: Three, Two, and One....202 Quiz: Private and Protected Constructor....203 Determine the Number of Switched on Electrical Devices....203 Ship Should Hold Any Electronic Device....203 Take Working Radios on the Ship....204 Solve Equivalence Test with Pattern Variable....204 Fire Alarm Does Not Go Off: Overriding Methods....205 Calling the Methods of the Superclass....205 Polymorphism and Dynamic Binding....206 Holiday! Switch Off All Devices....206 The Big Move....207 Quiz: Bumbo Is a Great Drink....208 Quiz: Vodka with Taste....209 Quiz: Rum-Paradise....209 Abstract Classes and Abstract Methods....209 Quiz: Consumer Devices as an Abstract Superclass?....210 TimerTask as an Example for an Abstract Class....210 Suggested Solutions....211 Declare Radio with Instance Variables and a Main Program....211 Implementing Methods of a Radio....212 Private Parts: Make Instance Variables Private....213 Create Setters and Getters....214 Convert Station Names to Frequencies....215 Write Log Output with a Tracer Class....215 Quiz: Nothing Stolen....216 Give Radio an AM–FM Modulation....216 Set Valid Start and End Frequency for Modulation....217 Writing Radio Constructors....218 Implement Copy Constructor....219 Realize Factory Methods....219 Connect Monitor Tube with TV....221 Quiz: Association, Composition, and Aggregation....222 Add Radios with a 1:n Association to the Ship....222 Introduce Abstraction into Electrical Devices via Inheritance....223 Quiz: Three, Two, and One....224 Quiz: Private and Protected Constructor....225 Determine Number of Switched on Electrical Devices....225 Ship Should Hold Any Electronic Device....226 Take Working Radios on the Ship....226 Solve Equivalence Test with Pattern Variable....227 Fire Alarm Does Not Go Off: Overriding Methods....227 Calling the Methods of the Superclass....228 Holiday! Switch Off All Devices....229 The Big Move....229 Quiz: Bumbo Is a Great Drink....229 Quiz: Vodka with Taste....230 Quiz: Rum-Paradise....230 Quiz: Consumer Devices as an Abstract Superclass?....231 TimerTask as an Example for an Abstract Class....231 Note....232 7 Records, Interfaces, Enumerations, and Sealed Classes....233 Records....233 Quiz: Which Statements Are True for Records?....233 Develop Record for Complex Numbers....233 Quiz: Records with Static Variables....234 Record Patterns....234 Interfaces....235 Compare Consumption of Electrical Devices....235 Find Electronic Devices with the Highest Power Consumption....236 Use Comparator Interface for Sorting....237 Static and Default Methods in Interfaces....237 Delete Selected Elements with Predicate....237 Enumeration Types (enum)....238 Enumeration for Candy....238 Deliver Random Candies....239 Tagging Candy with Addictive Value....240 Interface Implementations via an enum....241 Quiz: Aviso and Brig....242 Suggested Solutions....242 Quiz: Which Statements Are True for Records?....242 Quiz: Records with Static Variables....243 Quiz: Records with Static Variables....244 Compare Consumption of Electrical Devices....245 Find Electronic Devices with the Highest Power Consumption....246 Use Comparator Interface for Sorting....247 Static and Default Methods in Interfaces....247 Delete Selected Elements with Predicate....248 Enumeration for Candy....249 Deliver Random Candies....250 Tagging Candy with Addictive Value....250 Interface Implementations via an enum....253 Quiz: Aviso and Brig....254 8 Nested Types....255 Declare Nested Types....255 Set AM–FM Modulation to Radio Type....255 Write Three Kinds of Watt-Comparator Implementations....256 Nested Types Quiz....256 Quiz: Pirate Could Have Waved....256 Quiz: Name in a Bottle....257 Quiz: Get Me Another Bottle of Rum....257 Suggested Solutions....258 Set AM–FM Modulation to Radio Type....258 Write Three Kinds of Watt-Comparator Implementations....259 Quiz: Pirate Could Have Waved....260 Quiz: Name in a Bottle....260 Quiz: Get Me another Bottle of Rum....260 9 Exception Handling....261 Catching Exceptions....261 Get the Longest Line of a File....261 Identify Exceptions, Laughing All the Time....262 Convert String Array to Int Array and Be Lenient on Nonnumbers....262 Quiz: And Finally....263 Quiz: A Lonely Try....263 Quiz: Well Caught....263 Quiz: Too Much of a Good Thing....264 Quiz: Try-Catch in Inheritance....264 Throwing Custom Exceptions....264 Quiz: Throw and Throws....264 Quiz: The Division Fails....265 Writing Your Own Exception Classes....265 Show Impossible Watt with Own Exception....265 Quiz: Potatoes or Other Vegetables....265 Try-with-Resources....266 Write Current Date to File....266 Read Notes and Write Them to a New ABC File....266 Quiz: Excluded....267 Suggested Solutions....268 Get the Longest Line of a File....268 Identify Exceptions, Laughing All the Time....269 Convert String Array to Int Array and Be Lenient on Nonnumbers....271 Quiz: And Finally....272 Quiz: A Lonely Try....272 Quiz: Well Caught....273 Quiz: Too Much of a Good Thing....273 Quiz: Try-Catch in Inheritance....274 Quiz: Throw and Throws....274 Quiz: The Division Fails....274 Show Impossible Watt with Own Exception....275 Quiz: Potatoes or Other Vegetables....277 Write Current Date to File....277 Read Notes and Write Them to a New ABC File....278 Quiz: Excluded....279 10 Lambda Expressions and Functional Programming....280 Lambda Expressions....281 Quiz: Recognize Valid Functional Interfaces....281 Quiz: From Interface Implementation to Lambda Expression....281 Write Lambda Expressions for Functional Interfaces....282 Quiz: Write Lambda Expressions Like This?....283 Developing Lambda Expressions....283 Quiz: Contents of the Package java.util.function....283 Quiz: Know Functional Interfaces for Mappings....283 Method and Constructor References....285 Rewriting Lambda Expressions....285 Selected Functional Interfaces....285 Delete Entries, Remove Comments, Convert to CSV....285 Suggested Solutions....286 Quiz: Recognize Valid Functional Interfaces....286 Quiz: From Interface Implementation to Lambda Expression....287 Write Lambda Expressions for Functional Interfaces....288 Quiz: Write Lambda Expressions Like This?....288 Developing Lambda Expressions....288 Quiz: Contents of the Package java.util.function....288 Quiz: Know Functional Interfaces for Mappings....289 Rewriting Lambda Expressions....290 Delete Entries, Remove Comments, and Convert to CSV....290 Note....291 11 Special Types from the Java Class Library....292 Absolute Superclass java.lang.Object....292 Generate equals(Object) and hashCode()....293 Existing equals(Object) Implementations....293 Interfaces Comparator and Comparable....294 Quiz: Natural Order Or Not?....294 Handle Superheroes....294 Compare Superheroes....296 Concatenate Hero Comparators....297 Using a Key Extractor to Easily Create a Comparator....297 Sort Points by Distance to Center....299 Find Stores Nearby....300 Autoboxing....300 Quiz: Handling Null Reference in Unboxing....300 Quiz: Unboxing Surprise....301 Suggested Solutions....301 Generate equals(Object) and hashCode()....301 Existing equals(Object) Implementations....304 Quiz: Natural Order Or Not?....306 Compare Superheroes....306 Concatenate Hero Comparators....307 Using a Key Extractor to Easily Create a Comparator....308 Sort Points by Distance to Center....308 Find Stores Nearby....309 Quiz: Handling Null Reference in Unboxing....310 Quiz: Unboxing Surprise....311 Notes....311 Appendix A: Most Frequent Types and Methods in the Java Universe....312 A.1 Packages with the Most Common Types....312 A.2 100 Most Common Types....313 A.3 100 Most Common Methods....316 A.4 100 Most Common Methods Including Parameter List....319