LECTURE NOTES 
CHAPTER 1

ASSIGNMENTS
- surf web site
- read Chapter 1
- 1/26 notify me of exam conflicts/McBurnie accomodations

ADMINISTRIVIA

- introduce self
- office hours
- course difficulty
- course format
- participation policy
- exams
- pair programming


1.1 WHAT IS PROGRAMMING?

- computer
  - store data
  - communicate with devices
  - execute programs
- programming
  - telling a computer what to do
  - provide sequences of instructions
- program
  - instructions
  - decisions

1.2 THE ANATOMY OF A COMPUTER

- CPU
  - comprises chip/integrated circuit
    - plastic/metal housing
    - complex silicon wiring
    - transistors: elements that let electrical signals control each other
  - function: locate & execute instructions
      - arithmetic
      - interact with devices and storage
        - get data
        - send data
- storage: place to keep data and programs
  - primary/RAM/memory
    - fast
    - expensive
    - made of memory chips
    - volatile
  - secondary
    - less expensive
    - non-volatile
    - usually hard disk
      - magnetic-coated rotating platters
      - read/write head
  - removeable: floppy disk, tape, CD
- peripheral devices
  - purpose: interact with people
  - output: display, speakers, printer
  - input: keyboard, mouse
- bus: set of electrical lines connecting all of these components
- motherboard: houses CPU, primary storage, buses, and connections to devices
- networks: several computers connected together
  - types: dialup, broadband, local area
  - purpose: share data/workload
- executing a program
  - load program and data
  - follow instructions
    - read-modify-write data
    - interact with devices
    - use data to make decisions
  - very fast

1.3 TRANSLATING HUMAN-READABLE PROGRAMS TO MACHINE CODE

- machine instructions
  - instructions the CPU can actually execute
  - very simple
  - encoded as numbers
  - stored in memory
  - executed very quickly
  - varies among CPUs
- Java virtual machine
  - software that simulates a CPU
  - must write special software to execute it on each real CPU
  - allows portability
- communicate command sequence to computer
  - place data and commands in memory manually
  - high-level language plus compilers
    - use high-level language to express idea of what to do
    - compiler
      - special kind of program
      - translates a high-level language into a machine language
      - allocates memory to variables

1.4 THE JAVA PROGRAMMING LANGUAGE

- advantages
  - relatively simple
  - secure
  - virtual machine catches and reports many mistakes
  - rich libraries
    - portable
      - runs on all machines without changing the code
      - operating system independent
    - suitable for environments of varying size: small and large versions
- disadvantages
  - requires some syntax for even the most basic programs
  - multiple versions: 5.0 for this course
  - won't learn it all in one semester: too many library packages

1.5 BECOMING FAMILIAR WITH YOUR COMPUTER

- we will do this during a lab day this coming Wednesday
- we are using the integrated development environment Eclipse
- file
  - collection of items of information that are kept together
  - often system-dependent naming rules
  - extension: required by some systems at the end of the file (the .blah part)
  - Java
    - we must name our programs with the .java extension
    - spaces are not allowed
    - case-sensitive
- folder/directory
  - collection of files/folders
- backup

1.6 COMPILING A SIMPLE PROGRAM

- Hello, World example
- free-form layout, but this course grades on style -- see guidelines online
- class
  - create one
  - fundamental building block
  - class name and file name must match
- method
  - create one
  - contains a collection of programming instructions that describe how to carry 
    out a particular task
  - main: every application must have one
- method body
  - designated by curly braces
  - executed sequentially
- comment
  - ignored by the compiler
  - single line comment
  - multiple line comment
- statement
  - an individual instruction
  - must end with a semicolon
- calling an object's method

1.7 ERRORS

- compile-time/syntax
  - compiler finds
  - violation of the language rules
  - compiler does not translate program into VM instructions
  - usually displays all errors that aware of
    - sometimes one error can trick it into thinking there are multiple errors
    - solution: do top-down and recompile after fixing each one
  - compile frequently so that you aren't overwhelmed by too many errors at once
- run-time/logic/bug
  - does something other than what you intended
  - find these by extensive testing
  - defensive programming: structure so that errors as unlikely as possible to be 
    catastrophic

1.8 THE COMPILATION PROCESS

- edit-compile-test loop
  - type in the program statements (source code)
  - compile
    - turn source code into class files (virtual machine instructions)
    - generated files have the same name, but a .class extension
  - link: include any necessary library code
  - JVM runs the code