Chapter 1 
What is Java?
 - made by Sun in 1995, similar to C and C++
 - actually denotes a language and a platform

What's a Platform?
 - it includes the libraries, developer kit, compiler, and Java Virtual Machine (JVM)
 - the first three are very important to writing and making a program
 - the JVM is what actually runs a program once it is created (not all languages have this)

What's a programming language (PL)?
 - relation to human languages (HL):
   - similarities: both have punctuation, grammar, vocabulary, and a general way of expressing yourself
   - differences: programming languages are unambiguous, strictly enforce rules
 - syntax - what we call these rules in PL, basically a combination of HL grammar and vocab
   - important because a program must be syntactically correct to run
 - besides being syntactically correct, a program must be semantically correct
   - semantics relate to the meaning of a program, whether it runs the way it is expected to
   - bugs are often the result of semantic problems
 - besides HL, PLs borrow a lot from math
   - many of the first programmers and computer engineers were mathematicians
   - all the normal arithmetic operators are there: +, -, / (divide), * (multiply)
   - PL variables are very similar to math variables
   - graphics typically use the normal xy-coordinate system (or xyz for 3D), called Cartesian coordinates
   - trigonometry and linear algebra are used heavily
   - PL methods are very similar to the idea of a math function
 - PLs are something easy for humans to understand that get turned into machine-understandable code

What's Java (the language)?
 - it is a compiled, statically typed language
 - very popular because its platform enables it to be cross-platform, simplifies
    some of the more confusing parts of C/C++ (like garbage collection - ask me about it later)
 - it is NOT javascript
 - its "big thing" is that it is completely Object Oriented (we'll get to this later)

Hello World Revisited
public class HelloWorld
{
  public static void main( String args[ ] )
  {
    System.out.println( "Hello World!" ) ;
  }
}

 - public class HelloWorld defines a new Java class called HelloWorld
 - public static void main( String args[ ] ) defines a new function or method called main that takes an array of Strings as its arguments
   - main is the default beginning point when a program runs
 - System.out.println( "Hello World!" ) ; is the line that tells the JVM to output the thing between quotes to the screen
   - println( "Hello World!" ) is a method call
   - method calls have three parts: Object, method name, and parameters (optional)
 - the semicolon at the end is kind of like a period in English, it ends most statements
 - This won't all make sense yet, so don't worry
 - try changing some stuff.... what sorts of problems arise?
  - try 2+2 for example

+[Exercise: P1.1]+

Whitespace and Case
 - it is important to note that Java is not spacing sensitive so "public class HelloWorld { public static void main(String args[]){ System.out.println("Hello World!") ; }}" is the same as above
  - so, line breaks and spaces can often be left to how you want your code to look
  - I advise using the conventions that I and the book use
 - note that "words" have to have space, "public class HelloWorld" is different from "publicclass HelloWorld" which is different from "public class Hello World", etc.
 - in terms of casing, Java *IS* case sensitive
  - "public class HelloWorld" is completely different from "public class helloworld" or "PUBLIC cLaSS HelloWorld"
  - casing conventions are used for variable, method, package, and class names... we'll get to these later
  - not having the casing correct will lead to syntax errors
   - ex. if you don't name your main method exactly as "main" (say you call it Main) Java will complain about not being able to find the main method

Basic template of a program
public class ClassName
{
  // class variables go here, if any
  
  // now the methods, if any
  public void someMethod( )
  {
    ...
  }
  
  // finally the main method
  public static void main( String args[ ] )
  {
    ...
  }
}

Comments
 - comments inside code are lines of text that are NOT code, in other words not compiled and not part of the program
 - they are mostly written to explain code or concepts inside of the code
  - it is very important to comment your code!!!!
  - this especially becomes crucial when we learn about Javadoc
 - there are two types
   1. Single line comments - these have "//" at the beginning of the line and only last for a single line
     - if you look above I have several of these in the "basic template of a program"
   2. Multi-line comments - these start with "/*" and terminate with the first "*/"
     - something like:
       /* start my comment
          keep going
          more stuff
          System.out.println( "Hello World!" ) ; 
          this won't do anything because it's in a comment
          now I'm done! */
+[Exercises: P1.2, P1.5, P1.8]+

Backups **IMPORTANT**
 - it is VERY easy to make changes that mess up your program
  - you don't want to get stuck in a situation where you cannot take them back
 - thus, I recommend backing up your project folder each day before you begin and before any major code changes
 - do this by opening konqueror, navigating to ~/workspace, right-clicking on the project folder, hit add to archive, and name it
  - you can name them by appending dates, for example if your project is Wackadot then name the backup Wackadot06162008.zip, if you have multiple backups in a day append _#, like Wackadot06162008_2.zip