Language Fundamentals

Language Fundamentals

1. Encoding Sets

   • ASCII — American Standard Code for Information Interchange
     • Ascii – 7 bits, 128 charavters
     • Extended Ascii – 8 bits, 256 characters including german characters and British currency symbol
   • ISO — International Standards Organization
     • ISO-8859-1 AKA. Latin-1 – 8 bit character set containing characters required for writing text in all Western European languages
   • Unicode, developed by the NPO Unicode Consortium
     • A unique number = one character
     • Original Unicode characters were 16 bits, current are 32

2. Primitive Data Types

3. Variables

   • Every Variable must have a declared type
   • Reference Type
     • Variables provide reference to an object
   • Primitive Type
     • Variables hold a primitive
   • As well an an Identifier (name)
     • Can not be a Java keyword, a boolean literal, or the null literal
   • Declare a variable by writing the Type followed by the Identifier (followed by a semicolon – ";")
   • Must follow Sun's Naming Convention (Camel Naming) i.e. userName

4. Constants

   • Declare a constant by using the keyword "final"
   • Constant names are in all Upper-Case with words seperated by underscores "_" i.e. ROW_COUNT

5. Literals

   • The source code representation of a value
   • Primitive Literals
     • Integer Literals
       • Written in decimal (10), Hexadecimal (0x or 0X 9E), or Octal (0 567)
       • Used to assign values to variables of type Byte, Short, Int, and Long
         • To assign a value to Long, suffix the nuber with an "l or L" i.e. 1234567890L
         • Can use underscores (_) to seperate digits i.e. 1_000_000
         • Can also be expressed in binary by using the prefix 0b or 0B
     • Floating-Point Literals
       • Has the following parts: A Whole Number, a Decimal, a Fractional, and an Optional Exponent
       • Used to assign values to variables of type Float and Double
         • Floats can be written as (0.5, .5, 5(e/E)3, 5.0(e/E)3) followed by an f or F
           • Abscence of the 'F' makes the literal a Double
         • Doubles can be explicitely stated by suffixing the number with a d or D
     • Character Literals
       • A Unicode Character or Escape Sequence enclosed in single quotes (' ')
         • Character literals include: 'a', 'b', 'c', etc...
         • Escape Sequences include:
         • Java lets you escape a Unicode Caracter by using a sequence of ASCII Characters i.e. '⊙' can be written as '\u2299'
     • Boolean Literals
       • Has two values represented by the values True and False
   • String Literals
   • The Null Literal

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