Building Java Programs

Transcription

1 Building Java Programs A Back to Basics Approach Stuart Reges I Marty Stepp University ofwashington

2 Preface 3 Chapter 1 Introduction to Java Programming Basic Computing Concepts 26 Why Programming? 26 Hardware and Software 27 The Digital Realm 28 The Process of Programming 30 Why Java? 31 The Java Programming Environment And Now Java 34 String Literals (Strings) 38 System.out.println 39 Escape Sequences 39 print versus println 41 Identifiers and Keywords 42 A Complex Example: DrawFiguresl 44 Comments and Readability Program Errors 48 Syntax Errors 48 Logic Errors (Bugs) Procedural Decomposition 52 Static Methods 55 Flow of Control 58 Methods that Call Other Methods 60 An Example Runtime Error Case Study: DrawFigures 64 Structured Version 65 Final Version without Redundancy 67 Analysis of Flow of Execution 68

3 Chapter 2 Primitive Data and Definite Loops 2.1 Basic Data Concepts Primitive Types Expressions Literals Arithmetic Operators Precedence Mixing Types and Casting 2.2 Variables Assignment/Declaration Variations String Concatenation Increment/Decrement Operators Variables and Mixing Types 2.3 The for Loop Tracing for Loops for Loop Patterns Nested for Loops 2.4 Managing Complexity Scope Pseudocode Class Constants 2.5 Case Study: Hourglass Figure Problem Decomposition and Pseudocode Initial Structured Version Adding a Class Constant Further Variations Chapter 3 Introduction to Parameters and Objects 3.1 Parameters The Mechanics of Parameters Limitations of Parameters Multiple Parameters Parameters versus Constants Overloading of Methods 3.2 Methods That Return Values The Math Class Defining Methods That Return Values

4 3.3 Using Objects 179 String Objects 180 Interactive Programs and Scanner Objects 186 Sample Interactive Program Case Study: Projectile Trajectory 192 Unstructured Solution 196 Structured Solution 198 Supplement 3G Graphics (Optional) 212 3G.I Introduction to Graphics 213 DrawingPanel 213 Drawing Lines and Shapes 214 Colors 219 Drawing with Loops 222 Text and Fonts 226 3G.2 Procedural Decomposition with Graphics 229 A Larger Example: DrawDiaraonds 230 3G.3 Case Study: Pyramids 233 Unstructured Partial Solution 234 Generalizing the Drawing of Pyramids 236 Complete Structured Solution 237 Chapter 4 Conditional Execution if /else Statements 251 Relational Operators 253 Nested if /else Statements 255 Object Equality 262 Factoring if /else Statements 263 Multiple Conditions Cumulative Algorithms 266 Cumulative Sum 266 Min/Max Loops 268 Cumulative Sum with if 272 Roundoff Errors Text Processing 277 The char Type 277 char versus int 278

5 Cumulative Text Algorithms 279 System.out.printf Methods with Conditional Execution 286 Preconditions and Postconditions 286 Throwing Exceptions 286 Revisiting Return Values 290 Reasoning about Paths Case Study: Body Mass Index 297 One-Person Unstructured Solution 298 Two-Person Unstructured Solution 301 Two-Person Structured Solution 303 Procedural Design Heuristics 307 Chapter 5 Program Logic and Indefinite Loops The while Loop 326 A Loop to Find the Smallest Divisor 327 Random Numbers 330 Simulations 334 do/while Loop Fencepost Algorithms 337 Sentinel Loops 339 Fencepost with if The boolean Type 343 Logical Operators 345 Short-Circuited Evaluation 348 boolean Variables and Flags 352 Boolean Zen 354 Negating Boolean Expressions User Errors 358 Scanner Lookahead 359 Handling User Errors Assertions and Program Logic 363 Reasoning about Assertions 365 A Detailed Assertions Example Case Study: NumberGuess 371 Initial Version without Hinting 371 Randomized Version with Hinting 373 Final Robust Version 377

6 Chapter 6 File Processing File-Reading Basics 398 Data, Data Everywhere 398 Files and File Objects 398 Reading a File with a Scanner Details of Token-Based Processing 406 Structure of Files and Consuming Input 408 Scanner Parameters 413 Paths and Directories 414 A More Complex Input File Line-Based Processing 419 String Scanners and Line/Token Combinations Advanced File Processing 425 Output Files with PrintStream 425 Guaranteeing That Files Can Be Read Case Study: Zip Code Lookup 433 Chapter 7 Arrays Array Basics 450 Constructing and Traversing an Array 450 Accessing an Array 454 A Complete Array Program 457 Random Access 461 Arrays and Methods 464 The For-Each Loop 467 Initializing Arrays 469 The Arrays Class Array-Traversal Algorithms 471 Printing an Array 472 Searching and Replacing 474 Testing for Equality 477 Reversing an Array 478 String Traversal Algorithms Reference Semantics 484 Multiple Objects 486

7 7.4 Advanced Array Techniques 488 Shifting Values in an Array 488 Arrays of Objects 493 Command-Line Arguments 494 Nested Loop Algorithms Multidimensional Arrays 497 Rectangular Two-Dimensional Arrays 497 Jagged Arrays Case Study: Benford's Law 503 Tallying Values 505 Completing the Program 509 Chapter 8 Classes Object-Oriented Programming 525 Classes and Objects 526 Point Objects Object State and Behavior 529 Object State: Fields 530 Object Behavior: Methods 532 The Implicit Parameter 535 Mutators and Accessors 537 The tostring Method Object The Keyword Initialization: Constructors 541 this 546 Multiple Constructors Encapsulation 549 Private Fields 550 Class Invariants 556 Changing Internal Implementations Case Study: Designing a Stock Class 562 Object-Oriented Design Heuristics 563 Stock Fields and Method Headers 565 Stock Method and Constructor Implementation 567 Chapter 9 Inheritance and Interfaces Inheritance Basics 580 Nonprogramming Hierarchies 581

8 Extending a Class 583 Overriding Methods Interacting with the Superclass 589 Calling Overridden Methods 589 Accessing Inherited Fields 590 Calling a Superclass's Constructor 592 DividendStock Behavior 594 The Object Class 596 The equals Method 597 The instanceof Keyword Polymorphism 602 Polymorphism Mechanics 605 Interpreting Inheritance Code 607 Interpreting Complex Calls Inheritance and Design 612 A Misuse of Inheritance 612 Is-a Versus Has-a Relationships 615 Graphics2D Interfaces 618 An Interface for Shapes 619 Implementing an Interface 621 Benefits of Interfaces Case Study: Financial Class Hierarchy 626 Designing the Classes 627 Redundant Implementation 631 Abstract Classes 634 Chapter 10 ArrayLists ArrayLists 653 Basic ArrayList Operations 654 ArrayList Searching Methods 657 A Complete ArrayList Program 660 Adding to and Removing from an ArrayList 662 Using the For-Each Loop with ArrayLists 666 Wrapper Classes The Comparable Interface 670 Natural Ordering and compareto 672 Implementing the Comparable Interface 676

9 10.3 Case Study: Vocabulary Comparison 682 Some Efficiency Considerations 682 Version 1: Compute Vocabulary 685 Version 2: Compute Overlap 688 Version 3: Complete Program 693 Chapter 11 Java Collections Framework 703 M.I Lists 704 Collections 704 LinkedList versus ArrayList 705 Iterators 708 Abstract Data Types (ADTs) 711 LinkedList Case Study: Sieve Sets 717 Set Concepts 718 TreeSet versus HashSet 720 Set Operations 721 Set Case Study: Lottery Maps 725 Basic Map Operations 726 Map Views (keyset and values) 728 TreeMap versus HashMap 729 Map Case Study: wordcount 730 Collection Overview 733 Chapter 12 Recursion Thinking Recursively 743 A Nonprogramming Example 743 An Iterative Solution Converted to Recursion 746 Structure of Recursive Solutions A Better Example of Recursion 750 Mechanics of Recursion Recursive Functions and Data 760 Integer Exponentiation 760 Greatest Common Divisor 763 Directory Crawler 769 Helper Methods Recursive Graphics (Optional) 776

10 12.5 Case Study: Prefix Evaluator 780 Infix, Prefix, and Postfix Notation 781 Evaluating Prefix Expressions 781 Complete Program 785 Chapter 13 Searching and Sorting Searching and Sorting in the Java Class Libraries 799 Binary Search 800 Sorting 803 Shuffling 804 Custom Ordering with Comparators Program Complexity 809 Empirical Analysis 812 Complexity Classes Implementing Searching and Sorting Algorithms 818 Sequential Search 819 Binary Search 820 Recursive Binary Search 823 Searching Objects 826 Selection Sort Case Study: Implementing Merge Sort 830 Splitting and Merging Arrays 831 Recursive Merge Sort 834 Complete Program 837 Chapter 14 Graphical User Interfaces GUI Basics 847 Graphical Input and Output with Option Panes 847 Working with Frames 850 Buttons, Text Fields, and Labels 855 Changing a Frame's Layout 857 Handling an Event Laying Out Components 860 Layout Managers 861 Composite Layouts Interaction Between Components 869 Example 1: BMI GUI 869

11 Object-Oriented GUIs 870 Example 2: Credit Card GUI Additional Components and Events 879 Text Areas, Scrollbars, and Fonts 880 Icons 882 Mouse Events Two-Dimensional Graphics 889 Drawing onto Panels 889 Animation with Timers Case Study: Implementing DrawingPanel 896 Initial Version without Events 896 Second Version with Events 898 Chapter 15 Implementing a Collection Class Simple ArraylntList 911 Adding and Printing 911 Thinking about Encapsulation 917 Dealing with the Middle of the List 918 Another Constructor and a Constant 923 Preconditions and Postconditions A More Complete ArraylntList 928 Throwing Exceptions 928 Convenience Methods Advanced Features 934 Resizing When Necessary 934 Adding an Iterator ArrayList<E> 942 Chapter 16 Linked Lists Working with Nodes 954 Constructing a List 955 List Basics 957 Manipulating Nodes 960 Traversing a List A Linked List Class 967 Simple LinkedlntList 967

12 23 Appending add 969 The Middle of the List A Complex List Operation 980 Inchworm Approach An intlist Interface LinkedList<E> 989 Linked List Variations 990 Linked List Iterators 993 Other Code Details 995 Chapter 17 Binary Trees Binary Tree Basics 1006 Node and Tree Classes Tree Traversals 1010 Constructing and Viewing a Tree Common Tree Operations 1025 Sum of a Tree 1025 Counting Levels 1026 Counting Leaves Binary Search Trees 1029 The Binary Search Tree Property 1030 Building a Binary Search Tree 1032 The Pattern x = change(x) 1036 Searching the Tree 1039 Binary Search Tree Complexity SearchTree<E> 1044 Appendix A Answers to Self-Check Problems 1059 Appendix B Java Summary 1131 Appendix C Javadoc Comments and the Java API Specification 1146 Appendix D Additional Java Syntax 1152 Index I 161