Object-Oriented Programming

Object-Oriented Programming

1. Encoding Sets

   • Java supports Unicode character encoding set
     • 32-bit system is most convenient
     • A unique number represents exactly 1 character
     • Character encoding is like data compression
       • UTF-8, UTF-16, UTF-32
     • Can write Java code in other languages than English
   • Program element names are not restricted to ASCII characters
     • ASCII has 128 characters, each represented by 7 bits
     • Extended ASCII has 128 more characters, each represented by 8 bits.
   • Text can be written using practically any characters

2. Primitives

   • Simple non-object programming elements
   • byte (-128 yo 127)
   • short (short integer)
   • int (integer)
   • long
   • float
   • double ("double precision"; decimals)
   • char (character)
   • boolean (true/false)

3. Variables

   • data place holders whose contents can be changed
   • every one must have a declared type
     • reference types : provides a reference to an object
     • primitive types: holds a primitive
   • has a name & identifier
     • Identifiers must begin with a Java letter & must not be a Java keyword. It must be unique within its scope.

4. Constants

   • Place holders whose values cannot be changed
   • declare a constant by using the keyword final

5. Literals

   • representations of data values that are understood by the Java compiler
   • Integer Literals
   • Floating-Point Literals
   • Boolean Literals
   • Character Literals

6. Primitive Conversion

   • Changing the type of a primitive to another type

7. Operators

   • notations indicating that certain operations are to be performed

8. Separators

   • Parentheses ()
     • 1. method signatures to contain lists of arguments. 2. expressions to raise operator precedence. 3. narrowing conversions. 4. loops to contain expressions to be evaluated
   • Braces {}
     • 1. declaration of types. 2. blocks of statements 3. array initialization.
   • Brackets []
     • 1. array declaration. 2. array value dereferencing
   • Angle Brackets <>
     • Used to pass parameter to parameterized types
   • Semicolon
     • Used to terminate statements and in the for statement to separate the initialization code, the expression, and the update code.
   • Colon
     • Used in the for statement that iterates over an array or a collection
   • Comma
     • Used to separate arguments in method declaration
   • Period
     • Used to separate package names from subpackages and type names, and to separate a field or method from a reference variable.