Java Language Fundamentals

Java Language Fundamentals

1. Character Sets

   • ASCII
     • American Standard Code for Information Interchange
       • 7 bits = 128 characters originally
       • Extended to 8 bits = 256 characters
   • Unicode
     • Originally 16 bits = 65,000 characters
     • Extended to 32 bits
   • Character Encoding
     • reduces size of commonly used Unicode characters
     • UTF-8 transforms Unicode characters to various lengths, down to 8 bits
       • UTF-16 is used for 16 bit and 32 bit characters, UTF-32 for 32 bit characters

2. Seperators

   • ( )
   • { }
   • [ ]
   • < >
   • ;
   • :
   • ,
   • .

3. Primitive Data Types

   • floating point
     • float - 32 bit
     • double - 32 bit
   • integer-type
     • byte - 8 bit
     • short - 16 bit
     • int - 32 bit
     • long - 64 bit
   • char - Unicode
   • boolean

4. Variables

   • reference type - holds object
   • primitive type - holds a primitive
   • must have a name (identifier)
     • cannot start with numbers
     • case-sensitive
     • Sun's naming convention (i.e. myStudent)
   • declaration
     • value can also be assigned when declared

5. Java stores integers in binary

6. constants

   • declared with "final" keyword
   • cannot be changed
   • name is upper case

7. literals

   • source code representation of value
   • integers
     • specify base system if not in decimal
   • floating point
     • i.e. 2e+1f
   • boolean
     • i.e. true
   • character
     • i.e. 'A'
     • escape sequences
       • i.e. '\b' = backspace