Language Fundamentals

Language Fundamentals

1. Literals

   • When converting from a data type to another, the source code representation used to do so is called literal
     • Three types: Primitive types, string, and null
       • Primitive Types have four subtypes
         • Floating-point Literals
           • Has: a whole number part, decimal point, fractional part, and an optional exponent
             • Two types
               • Float, which is 32 bits in size
               • double, which is 64 bits in size
         • Integer Literals
           • Used to assign values of types byte, short, int, and long
             • Never exceed the value the type can withstand
         • Boolean Literals
           • Has two values, represented by True and False
         • Character Literals
           • A Unicode character or escape sequence enclosed in single quotes

2. Separators

   • Several characters Java uses as separators
     • Parentheses ()
       • Used in: method signatures, expressions, narrowing conversions, loops to contain expressions
     • Braces {}
       • Used in: declaration of types, blocks of statements, array intialization
     • Brackets []
       • Used in: array declaration, array value dereferencing
     • Angle brackets <>
       • Used to pass parameter
     • Semicolon ;
       • Used to terminate statements, used in the FOR statement
     • Colon :
       • Used in the FOR statement that iterates over an array
     • Comma ,
       • Used to separate arguments in method declarations
     • Period .
       • Used to separate package names from sub-packages and type names

3. Primitives

   • A data type, where there is 8 of them
     • byte, short, int, long, float, double represent numbers
       • Each is a different size, byte being the smallest
       • byte, int, short, and long only hold integers
     • Char represents a single character and boolean contains either true or false
       • Char can be any character of any language, number, or symbol

4. Variables

   • A data placeholder that provides a reference to an object
     • Has an identifier, which can be unlimited in length but: must begin with a Java letter, not be a Java keyword, a boolean literal, a null literal, and unique within its scope
       • Identifiers are case sensitive
       • Declare by writing type, then the name, plus a semicolon

5. ASCII and Unicode

   • One of the many computer languages available
     • Unicode was invented as an attempt to include all characters in all languages into a single set
       • Had to resort to 32 bit in order to store all this information, which is too much to process
         • Character encoding made it more efficient to store and transmit Unicode