CSC 142/Chapter 1

Chapter 1: Intro to Java

Sections:

1.1 Basic computing concepts

1.2 And now, Java

1.3 Program errors

1.4 Procedural decomposition

1.5 Case study: DrawFigs

Note: the first chapter is definitions-heavy.

Section 1.1: Intro to Java

Definitions

• Algorithm
• Program
• Hardware ("Hardware: the part of the computer that you can kick")
• Software
• Digital
• Binary
• Program execution
• Compiler
• Java Virtual Machine (JVM)
• Java Runtime Environment (JRE)

Material

Things to cover:

• Java class libraries (standard library)
• Java programming environment
• Java Hello World program
• Console window/command line

1995: Oracle: "Java: A simple, object-oriented, network-savvy, interpreted, robust, secure, architecture-netural, portable, high-performance, multithreaded, dynamic language."

Life Skills

Life skills track:

• Pay attention and FOCUS
• RTFM
• Follow directions and read carefully
• Whether it's your compiler, or your instructor, or your fellow students - pay attention to what's being said
• Skill will pay off when you start to compile your Java programs

Section 1.2: Java

Materials

Class

• Every program, all Java code, lives in a class
• Class header
• Class methods
• Statements
• String literals
• System.out.println
• Escape sequences
• print vs println

Complex example: draw figures

• ASCII diamond, X, rocket

Code comments, white space, readability:

• Comments

Section 1.3: Syntax Errors

Material

Different types of errors:

• Where the errors happen - the normal process - (code) --> (compiler) --> (bytecode)
• Errors at compiler level - syntax errors - book lists common syntax errors
• Errors at code level - bugs - errors in the logic of the program (wrong idea, or right idea but implemented wrong)

Section 1.4: Procedural Decomposition

Materials

Decomposing complexity:

• Decomposition concept: split into functions, tasks, subtasks

C is very verb-oriented, action-oriented

Java is very noun-oriented, object-oriented

Procedural programming:

• Function-based, action-based programming
• How to decompose task of baking a cake
• Static methods (help serve function of.......... functions)

Object oriented programming version:

• c = new Cake(); c.make()
• Encapsulating complexity of the object
• Example in book: drawBox, drawTopX, drawBottX

Flow control

• How control changes with function calls
• Objects: with OOP it becomes more complicated to follow the flow of the program
• Procedural programs and interpreted languages: you just start at the top and go from there
• Objects: "when is this code actually used?" (have to dive in to see)
• Learning to follow program flow control
• Flow control allows you to abstract away detail
• Example runtime error

Definitions

• Decomposition
• Iterative enhancement
• Static method
• Method call
• Flow control

Life Skills

Life skills track:

• Cover non-word representations of programs

(Give them a crypto puzzle, but we haven't introduced any crypto or codes just yet)

Section 1.5 : Case Study with DrawFig

Material

Modularization of drawing program

• Breaking into pieces - not just the box, or the x, or the rocket
• but breaking down into common components, common to all parts of the program
• Take hello world program...
• Modularize it, make it reusable...

Chapter 1 Summary

Worksheet: definitions from book on one side (quiz material)

Source code for a procedural program (fizz baz foo bar buzz bam) on the other

There are N bugs, find the N bugs (self-work)

Discuss the program flow with a partner (group work)

How do we represent this program in a clear and concise way?

Transform foo bar into get ready for school - proper names can help clarify understanding

Lecture: broken up into 1.5 parts

• Broad brush-stroke over chapter 1
• Memorize definitions
• Know XYZ for quiz
• Spend a majority of time on in-class exercises
• FOCUS: KNOW HOW TO RUN/SET UP HELLO WORLD
• FOCUS: KNOW DEFINITIONS
• FOCUS: KNOW FUNCTIONS AND PROGRAM FLOW
• FOCUS: KNOW ERRORS/EXCEPTIONS

Quiz/exam/assessment material:

• Hello world, basics, public static void main, syntax
• Definitions matchup
• Functions questions
• Program flow questions
• Exceptions: spot the bug... spot logical errors... spot syntax errors...

Need to make beginnings of class difficult, to send the message that they can't let it slide

Deliverables

Intro to Java

• Know how to set up and run hello world
• How does it work, role of compliler vs editor
• JRE vs JVM vs JDK
• Public static void main
• EEverything is a class
• Filename = class name
• Correct syntax, protected keywords

Definitions

• algorithm, program, hardware/software, digital, binary, program execution, compiler, JVM, JDK, JRE, class header, class methods, statements, string literals, system.out.println, escape chars, print vs println, exception, decomposition, flow control, iterative enhancement, static method

Functions and program flow

• How to follow the flow of a program through multiple (nested) function calls
• When to use a static method or static class
• How to follow a nested program
• How to break up a task into less complex parts, with reusability
• Translate between procedure and function

Errors and logical problems

• Spotting the error
• Red herring: error, plus (unclear) compiler output

Chapter 1 Code

Lecture Code

Fake rocket code - DrawFig

• Ascii draw a rocket
• From Reges and Stepp
• No patterns/functions until next section
• Cover exceptions
• Tie in with the Java API, let them know it exists and where it is, we'll talk more about it and how to use it in the future

Real rocket code - Vertical (solve a basic equation)

• Good to keep math at the forefront. Just throwing it out there.

Worksheet Code

Density code, DensityConversion code

• Description: write a program that prints a physical property of your choice for ten different chemical compounds (in metric units). Write another program that prints the physical property of your choice (in English units).
• Example: Look up densitiy, (g/cm3). Program to print 10 densities, in g/cm3. Then, program to convert to lb/ft3, and print 10 densities, in lb/ft3.
• Specifications: Your program must print a banner or header that states the physical property. Your program must print the (correct) units of the physical property.
• Submitting: Deliverables, what to turn in, what NOT to turn in, what format, how, when, with what

Homework Code

(What homework problems?)

Chapter 1 Goodies

Profiles

• James Gosling - Oracle, tech companies, open source vs. enterprise, hackers vs suits
• Grace Hopper

Puzzle 1

How the puzzles work:

• Follow along, we'll cover material you need after the fact
• If you can figure the puzzle out ahead of time, can get extra credit
• If you are having trouble getting started, prior puzzles may provide hints

Puzzle 1:

• No points, getting them started

public class Something {
  public static void main(String[] args) { 
    System.out.println("The secret word is xyz");
  }
}