CHAPTER 1

1. CHAPTER 1 INTRODUCTION

2. CHAPTER GOALS • To understand the activity of programming • To learn about the architecture of computers • To learn about machine code and high level programming languages • To become familiar with your computing environment and your compiler • To compile and run your first Java program • To recognize syntax and logic errors

3. PREREQUISITES • Computer savvy (file management, text editing) • Problem solving skills • Time management • High school math (Geometry, Algebra II) • No prior programming background required

4. What do computers do? • Help with organizing and writing term papers • Help balance checkbooks • Keep track of students' grades • They are even good game machines

5. How do computers do it? • Computers must be programmed to perform tasks. Different tasks require different programs. • A computer program executes a sequence of very basic operations in rapid succession

6. What is a computer? • Central processing unit • Memory • Peripherals • Executes very simple instructions • Executes instructions very rapidly • General purpose device • Programs describe specific actions

7. Self Check 1. What is required to play a music CD on a computer? Ans: A program that reads the data on the CD and sends output to the speakers and the screen. 2. Why is a CD player less flexible than a computer? Ans: A CD player can do one thing–play music CDs. It cannot execute programs.

8. Self Check Cont… 3. Can a computer program develop the initiative to execute tasks in a better way than its programmers envisioned? Ans: No–the program simply executes the instruction sequences that the programmers have prepared in advance.

9. Central Processing Unit

10. CPU and what it does • A single chip consisting of millions of transistors • performs program control • arithmetic operations • data movement

11. A Memory Module with Memory Chips Figure 2: A Memory Module with Memory Chips

12. A Hard Disk Figure 3: A Hard Disk

13. A Motherboard Figure 4: A Motherboard

14. Schematic Diagram of a Computer Figure 5: Schematic Diagram of a Computer

15. The ENIAC Figure 6: The ENIAC

16. Self Check 4. Where is a program stored when it is not currently running? Ans: In secondary storage, typically a hard disk. 5. Which part of the computer carries out arithmetic operations, such as addition and multiplication? Ans: The central processing unit.

17. Programming Languages • Machine/Virtual Machine21 40 16 100 163 240 • Assembleriload intRatebipush 100if_icmpgt intError • High-level languageif (intRate > 100) . . .

18. Compilers • Language specific • Sophisticated programs that • translate logical statements such as ifs into sequences of computations, tests and jumps • find memory locations for variables • and more . . .

19. The Java Programming Language • Simple • Safe • Platform-independent ("write once, run anywhere") • Rich library • Designed for the internet

20. Applets on a Web Page Figure 7: Applets on a Web Page

21. Java Versions

22. Self Check 5. What are the two most important benefits of the Java language? Ans: Safety and portability. 6. How long does it take to learn the entire Java library? Ans: No one person can learn the entire library–it is too large.

23. HOMEWORK! • Complete the computer room agreement form and have it signed by parent/guardian • Be sure you have a computer password • Read and take notes section 1-1 through 1-6 and complete the self-check exercises. • italicized words -- vacabulary • boxes • points of interest (ENIAC) • p. 29 exercises R1.1 – R1.3 to be collected tomorrow with the self check exercises.

24. Becoming Familiar with your Computer • Login • Locate the Java compiler • Understand files and folders • Write a simple program (later) • Save your work

25. A ConsoleWindow

26. An Integrated Development Environment Figure 9:An Integrated Development Environment

27. A simple program • public class ClassName • public static void main(String[] args) • // comment • Method call object.methodName(parameters) • System class • System.out object • println method

28. File Hello.java 1 public class Hello 2 { 3 public static void main(String[] args) 4 { 5 // display a greeting in the console window 6 System.out.println("Hello, World!"); 7 } 8 } • Output: • Hello, World!

29. A Simple Program • public class ClassName • public static void main(String[] args) • // comment • Method call Figure 13:Calling a Method System Class System.out Object println Method

30. Self Check 7. How would you modify the HelloTester program to print the words "Hello," and "World!" on two lines? Ans: 8. Would the program continue to work if you omitted the line starting with //? Ans: Yes–the line starting with // is a comment, intended for human readers. The compiler ignores comments. System.out.println("Hello,");System.out.println("World");

31. Self Check cont… 9. What does the following set of statements print? Ans: The printout is My lucky number is12. (It would be a good idea to add a space after the is. ) System.out.print("My lucky number is");System.out.println(3 + 4 + 5);

32. Errors • Syntax errorsSystem.ouch.print("...");System.out.print("Hello); • Detected by the compiler • Logic errorsSystem.out.print("Helop"); • Detected (hopefully) through testing

33. Self Check 10. Suppose you omit the // characters from the HelloTester.java program but not the remainder of the comment. Will you get a compile-time error or a run-time error? Ans: A compile-time error. The compiler will not know what to do with the word display. 11. How can you find logic errors in a program? Ans: You need to run the program and observe its behavior.

34. From Source Code to Running Program

35. The Edit-Compile-Test Loop

36. CLASSWORK/HOMEWORK! • R1.11 Use the Hello.java program to create different syntax errors. Record these errors. Then use the program to create a logic error. Describe the error you created. • Do Exercises p 30 – 31 P1.1, P1.2, P1.4 - P1.7 • At home Read sections 1.7 through 1.8 taking notes (pp 23-27) • On p 29 do review exercises R1.4 – 1.6, R1.10, and R1.12 to hand in. • Project 1.1