Jaeki Song

1. Lecture 01 Introduction to Java Programming Jaeki Song

2. Instructor • Name: Jaeki Song • Office: BA 712 • Office Hours Tuesday & Thursday 10:00-Noon or by appointment • Office Phone: (806) 742-8036 • E-mail: jsong@ba.ttu.edu • Website: http://jsong.ba.ttu.edu

3. Course Materials • Required Textbook Deitel and Deitel, Java How to Program, 4th Edition, Prentice Hall

4. Course Objectives • Objectives • Introduce OOP using JAVA • Understand JAVA programming • Understand the issues related to web-programming using JAVA • Emphasize critical thinking about new developments

5. Grading • First Exam: 20% • Second Exam: 20% • Third Exam: 30% • Assignments: 30%

6. Course Structure • Fundamentals of programming • Object-oriented programming • Graphics programming • Developing comprehensive programming

7. Objectives • Basics of Programming Language • What is Java? • Introduction to Java Applications

8. 1. Analyze Problem - Review program specification - Meet with users - Identify program components 2. Design Program - Group activity into modules - Devise solution algorithms - Test solution algorithms 6. Maintain Program - Identify errors - Identify enhancements 5. Formalize Solution - Review program code - Review documentation - Implement program 3. Code Program - Translate solution algorithm - Enter program code into computer 4. Test Program - Remove any syntax error - Remove any logic error Program Development Life Cycle (PDLC)

9. Structured Programming • Hierarchical Input Process Output (HIPO) chart • Algorithmic Thinking • Pseudocode • Flowchart • Storyboard

10. Top-Down Design • One method that is useful when defining the procedures to be used is termed Top-Down Design. With Top-Down Design you • break down a problem down into functional tasks or parts; • break each part, or task, into sub-parts; • continue the ‘chunking-up’ process until the sub-parts, or sub-tasks, are very simple and easily described.

11. HIPO Chart Main Initialization Process Wrap-up Declare Variable Print Report Read a record Calculate Accumulate total Print Detail Calculate average Print total And averages Calculate Gross amount Calculate discount Calculate net Amount due

12. Algorithmic Thinking • Correct • Using logical constructs and valid data in an organized way • The steps will be carried out correctly • The program will make suitable response • Efficient • The program’s ability to deliver a results in a time short enough to be useful and in a space small enough • An algorithm can be defined in various ways. Two common ways include the use of pseudocode and flowchart

13. uses English-like phrases to describe the instructions List the actions using keywords Depicts logical grouping or structures using indentation MAIN MODULE: Call Initialization Call Process Call Output END PROCESS MODULE: Do While not End of File Read a record Call Calculate Call Accumulate Print Detail Line End Do RETURN CALCULATE MODULE: If Hours > 40 then Call overtime Else Call Regular time End If RETURN Pseudocode

14. Flow Chart Process Symbol Represent process Makes data available for processing (input) or Displaying (output) of process information I/O Symbol Decision symbol Represents a decision that determines which Of number of alternative paths is to be followed Connector symbol Represents any entry form, or exit to, another part of the flow chart Represents the beginning, the end, or a point of Interruption or delay in a program Terminal symbol

15. Storyboard Interest Calculator principalLabel amtLabel Principal: principalField intLabel intField InterestRate: Amount Paid: monthsLabel amtlField Months: monthslField Calculate Clear calButton clearButton

16. What is Java? • Computer programming language • Computer program • A set of instructions • Programming language • A set of words, symbols, and codes • Syntax • A set of grammar or rules that specify how the instructions are to be written

17. History of Java • Designed in the early of 1990s by Sun Microsystems • Provide animation and interactivity on the World Wide Web • Web browsers have provided the opportunities to run Java applets • The fastest growing language

18. Java Language • Standard language used for programming, creating applets, servlets, JavaBeans, and enterprise components • Java is simple • Java is object-oriented language • Java is distributed

19. Java is interpreted Need an interpreter to run Java program The program are compiled into Java Virtual Machine (JVM) code called bytecode Java Language Java Source Code Java compiler Java Bytecode Code JVM Java Interpreter CPU

20. Java Language • Java is robust • Reliabile • Detect many problems • Java is secure • Java is platform-independent • Java is portable • Can be run on any platform without being recompiled • Java is multithreaded

21. Java Virtual Machine (JVM) • Interpreter for the Java programming language • a simple platform that all Java applications run on. • Comes with Java Development Kit (JDK) • Contains JVM and run-time system • Java 2 SDK • www.sun.com

22. Java Environment • Editor • Integrated Development Environment (IDE) • Jbuilder, J++, Forte, Visual Cafe • Compiler • Translate into bytecode • For Sun Microsystems- javac (included in SDK) • Class loader produces .class file • Loading • Applications • loaded and executed using Java Interpreter java example.class • Applet • loaded in the browser and could be viewed by applet viewer using the html file in which the applet is placed.

23. Creating First Application • The Java 2 Platform, Standard Edition • JBuilder4 or 5

24. JBuilder: Interface Content pane File tab Main menu Project toolbar Project pane Structure pane File view tab

25. Example /* Assignment 1 Printing on the screen Programmer: Jaeki Song Student ID : 999-99-9999 Date : September 2001 Program Name: Address */ public class Address { public static void main(String[] args) //method header { System.out.println(“ Jaeki Song”); System.out.println(“ 1234 89th Street”); System.out.println(“ Lubbock, TX, 79413”); } }

26. Documentation • Comments • Block comment /* ….. */ • Line comment: // • e.g. /* Assignment 1 Printing on the screen Programmer: Jaeki Song Student ID : 999-99-9999 Date : September 2001 Program Name: Address */

27. Java Class • Java program consists of pieces called classes • Existing classes in Java Class Libraries • Known as Java APIs (Applications Programming Interfaces) • Classes consists of pieces called methods • Perform tasks and return information

28. Java Class • A single class resides in a single Java source file with extension .java • public class Address { …. } • The source code is Address.java. • The name of the class is the name of the file • Class name and file name must match

29. Main Method • The class which contains the main() method is the class that starts running the program • Every Java application (not applet) has a main class public class Address { public static void main(String[] args) { … } }

30. Access Modifier • Specifies the circumstances in which the class can be accessed • E.g.: public class Address { ……. } • Public indicates that this code can be access by all objects and can be extended or used as a basis for another class • The contents of the class must be enclosed in braces { }

31. Void means that this method does not return a value when it is called Method name is main. Main method is the usual starting point for all stand-alone Java program Piece of data. args is an identifier for any string or character argument Methods and Method Header public staticvoidmain(String[] args) //method header { …… } • Three parts • return value • method name • arguments lists The method as accessible to all classes This method is for class

32. System is the name of the class (program-defined class) Println is the name of a method that takes a string argument. It returns its value to the System.out device Body Code { System.out.println(“ Jaeki Song”); System.out.println(“ 1234 89th Street”); System.out.println(“ Lubbock, TX, 79413”); } Out is the object that represents the default display

33. Variable • Used to store data • Variable declaration • To use a variable, you declare it by telling the compiler the name of the variable as well as what type of data it represents datatype variableName e.g int x; //Declare x to be an integer variable double interest; char a; //Declare a to be a character value int x, y, z;

34. Assignment • After a variable is declared, you can assign a value to it by using an assignment statement variable = expression; e.g. x = 1; //Assing 1 to variable x x = y + 1 ; //assign the addition of y and 1 to x • You can declare variable and initialize it in one step int x; x = 1 int x = 1;

35. Constant • A constant represents permanent data that never changes final datatype CONSTANTNAME = VALUE; In java, the world final means that the constant cannot be changed. e.g. final double PI = 3.14159;

36. Numeric Data Types • The Java Built-In data type • int: always 32-bit signed integer. • short: 16-bit integer. • byte: 8-bit integer (new). • long: 64-bit singed integer. • float: 32-bit floating-point number. • double; 64-bit floating-point number. • char: Unicode (16-bit, language independent character value, international standard. • boolean: true or false, false is not 0 in Java

37. Numeric Operators Operator Example Equivalent += i+=8 i = i+8 -= f-=8.0 f = f-8.0 *= i*=8 i = i*8 /= i/=8 i = i/8 %= i%=8 i = i%8

38. Increment and Decrement Operators • Increment or decrement a variable by 1 X++ or X--; suffix ++X or –X; prefix • Suffix operator: the variable is used in the expression first, then incremented or decremented by 1 • Prefix operator: the variable is first incremented or decremented by 1, then used in the expression

39. Relational Operators • Relational operator Operator Name Example Answer < less than 1 < 2 true <= less than or equal to 1 <=2 true > greater than 1 > 2 false >= greater than or equal to 1 >= 2 false = = equal to 1 = = 2 false != not equal to 1 != 2 true

40. Boolean Operators • Boolean variable • A variable that holds a Boolean value (true or false) Operator Name Example ! Not && and true && true  true | | or false | | false  false

41. Programming Style and Documentation • Appropriate Comments • Every program has the following block comment appear at the top of the source code file: /* Programmer: Jaeki Song Course: ISQS 6337 File Name: Assign1XXXX.java Description: A brief description of the program */

42. Programming Style and Documentation • Naming conventions • Make sure the meanings of the descriptive means you choose are straightforward • Names are case-sensitive • For variables and methods • Use lowercase • If the name consists of several words, concatenate them into one, making the first word lowercase and capitalizing the first letter of each subsequent word e.g: calculateSalary • For class names • Capitalize the first letter of each word e.g; ComputeSalary • For constants • All letters are capitalized e.g.: MAX_VALUE = 10

43. Programming Style and Documentation • Proper indentation and spacing • Clear and easy to read e.g.: public class Test { public static void main(String args[]) { System.out.println(“Example”); } }

44. Programming Errors • Syntax error • Result from errors in cod construction • E.g.: mistyping, omitting some necessary punctuation, using an opening brace without a corresponding closing brace • Logical error • Occur when a program does not perform the way it was intended to • Run-time error • Cause a program to terminate abnormally • E.g. • Input error: the user enters an unexpected input value that the program cannot handle • Division by zero

45. Formatting Output • Escape characters Code Concept Result \t Horizontal tab Moves insertion point eight spaces to the right \b Backspace Moves insertion point one space to the left \n New line Moves insertion point down one line and to the left margin \r Carriage return Moves insertion point to the left margin \” Double quote Used to print a double quote character

46. Using Java Swing Class • Refers to the new library of GUI • A component set that makes up all the objects of GUI • Displays output using windows or dialog boxes • Input Dialog and Output Dialog • Use packages • Predefined classes grouped into categories of related classes called packages (sometimes called java class libraries or java applications programming interface (API)) • JOptionPane • Defined in a package called javax.swing

47. Output Dialog • showMessageDialog ( null, “string”); • A method of class JOptionPane • Two arguments • Syntax JOptionPane.showMessageDialog(null, “string”);

48. Example: Output Dialog import javax.swing.JOptionPane; //import class JOptionPane public class Address { public static void main(String[] args) //method header { JOptionPane.showMessageDialog( null, " Jaeki Song\n1234 89th Street\n Lubbock, TX, 79413"); System.exit(0); //terminate program } }

49. Output

50. Input Dialog • Uses predefined dialog box from class JOptionPane called input dialog • Allows the user to input a value for use in the program • Syntax JOptionPane.showInputDialog(“ Enter first integer”);