Chapter 2: Language Fundamentals

Chapter 2: Language Fundamentals

1. ASCII

   • character set used to rep alphanumeric characters
     • Each character is rep by 7 bits
       • 128 characters in the set
     • Lower and Upper case, Latin letters, numbers and punctuation
       • Extended: extended ASCII
         • German character and British currency symbol
           • 128 more characters
             • each character rep by 8 bits
         • 2 of many characters set available

2. Unicode

   • character set
     • each chara was rep by 16 bits
       • rep more than 65k chara
         • Wanted to encode more characters (million)
           • Problem: storing and transmitting Unicode not as efficient
             • Solution: character encoding can make it more efficient to store and transmit Unicode
               • Three character encoding
                 • UTF- 8
                 • UTF -16
                 • UTF- 32

3. Separators

   • several characters that are Java uses
     • ( )
       • used in: 1. method signatures to contain list of arguments
       • 4. expressions to raise operatior precedence
       • 2. Narrowing conversion
       • 3. loops to contain exp to be evaluated
     • { }
       • Used in... 1. declaration of types
       • 2. blocks of statements
       • 3. array initializations
     • [ ]
       • Used in: 1. array declaration
       • 2. array value dereferencing
     • < >
       • used to pass parameter to parameterized types
     • :
       • used in FOR statment that iterates array/ collection
     • ;
       • to terminate statments and in FOR statement to separate initialization code, exp, update code
     • , (comma)
       • separates agruments in declaration
     • . (period)
       • separate package names from subpackages and type name
       • separate a field or method from a ref variable

4. Primitives

   • data value
     • 8 types
       • byte
       • short
       • int
       • long
         • hold integers/ whole number
       • float
       • double
       • char
         • Contains single Unicode chatacter
         • contain other charcters not in English
       • boolean
         • contains one of two states (False/True)

5. Variable

   • data placeholders
   • needs declared type
     • ref variable: providing ref to an object
     • primitive types: holds primitive
   • has name/ identifier
     • identifier: unlimisted- length sequence of letters/digits
       • not have java keyboard, boolean/null literal
       • unique

6. Constant

   • variables whose values cannot be changed
   • declare by "finish"

7. Literals

   • Code rep
   • 3 types: primitives types, string, and null
     • integer literals
       • decimal
       • assign values to variables of types short, byte, int, and long
         • For long: suffix number "L"
           • w/o ---> int
   • Floating- points literals
     • Parts:
       • whole #
       • decimal pt
       • fractional part
       • optional exponent
     • two types
       • Float: 32 bits in size
       • double: 64 bits
   • Boolean
     • true
     • false
   • character literals
     • Unicode character/ escape sequence enclosed in single quotes
       • escape sequence: rep of Unicode chara that cant enter using keyboard/ has spec func in JAVA