1. CHAPTER 1 INTRODUCTION 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

2. PREREQUISITES Computer savvy (file management, text editing)  Problem solving skills  Time management  High school math (algebra, trigonometry)  No prior programming background required

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

4. Central Processing Unit (CPU)

5. Schematic Diagram of a Computer

6. What Is A Program? Program: a sequence of instructions that tell computer to perform a specific task Programming: how to organize the sequence of instructions Programming language: a set of conventions that represent the instructions Details of instruction description –machine code –assembler –high-level

7. Programming Languages  Machine/Virtual Machine -- binary code: 21 40 16 100 163 240  Assembler iload intRate bipush 100 if_icmpgt intError  High-level language if (intRate > 100)...  Translating to machine code  Machine code is the only code that computers can recognize  Assembler and high-level languages must be translated to machine code  Two ways for translation  Interpretation  Compilation

8. The Java Programming Language  A high-level language  Simple  Safe  Platform-independent ("write once, run anywhere")  Rich library  Designed for the internet  Object-oriented

9. Applets on a Web Page

10. Becoming Familiar with your Computer Login Locate the Java compiler Understand files and folders Write a simple program (later) Save your work Backup copies –frequently save your file to disks

11. A Shell Window

12. An Integrated Development Environment

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

14. 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

15. Some Java Characteristics Case-sensitive Free-form layout A Java program must have one and only one method, called main, which is the program entrance Two ways for comments –// -- comment a single line –/*... */ -- comment a paragraph Escape sequence: \character –Special characters that can not be displayed: e.g. \n –Specially used characters: e.g. \” –Non-English letters: e.g. è

16. Syntax 1.1: Method Call Syntax: –object.methodName(parameters) –class.methodName(parameters) Example: System.out.println("Hello, Dave!"); Purpose: To invoke a method of an object and supply any additional parameters

17. Compiling and Running  Type program into text Editor  Save to disk (hard or floppy disk)  Open command shell  Compile into byte codes -- Compiler javac Hello.java  Execute byte codes -- Interpreter java Hello

18. From Source Code to Running Program

19. Errors  Syntax errors (or compile-time error) –Detected by the compiler –Examples: vMisspelling words: System.ouch.print("..."); vCase-sensitive: system.out.print("Hello”);  Missing something: System.out.print( "Hello);  Semantics error (or Logic errors or Run-time error )  Detected (hopefully) through testing  Examples: vSystem.out.print("Hell");

20. The Edit-Compile-Test Loop