Java OOP

Java OOP

1. Literals

   • primitive types
     • Integer literal
       • decimal (base 10)
       • hexadecimal (base 16)
         • prefix 0x or 0X
       • octal (base 8)
     • floating point literal
       • whole number
       • decimal point
       • fractional part
       • optional exponent
     • boolean literal
       • true
       • false
     • character literal
       • unicode character
       • escape sequence enclosed in single quotes
   • string literals
   • null literal

2. Separators

   • Parentheses ()
     • method signatures to contain list of arguments
     • expressions to raise operator precedence
     • narrowing conversions
     • loops to contain expressions to be evaluated
   • Braces {}
     • declaration of types
     • blocks of statements
     • array initialization
   • Brackets []
     • array declaration
     • array value dereferencing
   • Angle Brackets <>
     • used to pass parameter to parameterized types
   • Semicolon ;
     • used to terminate statements
     • to separate the initialization code, expression, and update code
   • Colon :
     • iterates over an array or a collection
   • Comma ,
     • used to separate arguments in method declarations
   • Period .
     • separate package names from subpackages and type names
     • separate a field or method from a reference variable

3. Constants

   • variable whose values are final

4. Encoding Sets

   • Types of Character Sets
     • ASCII
       • Represented by 7 bits
     • ISO
       • Represented by 8 bits
     • Unicode
       • Includes all characters of all languages
       • 32 bits
       • UTF-8
         • Most popular for HTML
         • Same byte values as ASCII
       • UTF-16
         • In single 16 bit code unit
       • UTF-32
         • Uses 32 bits for characters
         • Not a choice for internet applications
   • Uses different languages

5. Variables

   • Data placeholders
   • reference types
     • reference to an object
   • primitive types
     • holds a primitive
   • Identifier
     • unlimited length sequence
     • Unique within scope
     • can't be a Java keyword

6. Primitives

   • Byte
     • #'s between -128 to127
   • Long
     • between -2^63 to 2^63-1
   • Short
     • between -2^15 to 2^15-1
   • int
     • between -2^31 to 2^31-1
   • float
     • 14e^-45 to 3.4^e38
   • double
     • -4.9e^324 to 1.797e^308
   • char
     • unicode character
   • boolean
     • true or false