Java

Java

1. Character Sets

   • ASCII
     • 128 characters
       • 7 bits each
     • Lower & Uppercase latin letters, numbers, punctuation
     • Extended ASCII
       • Additional 128 characters
         • 8 bits each
     • Used for almost all input elements
   • Unicode
     • Attempts to include all characters from all languages
       • 65k characters
         • 16 bits each
     • 4x as much data as ASCII
       • UTF8, UTF-16, UTF-32 to make data transfer more efficient

2. Separators

   • Parentheses
     • method signatures, raise operator precedence, narrowing conversions, loops
   • Braces
     • Declaration of types, blocks of statements, array initialization
   • Brackets
     • array declaration, array value dereferencing
   • Angle brackets
     • pass parameters to parameterized types
   • Semicolon
     • terminate statements, in the for statement to separate the initialization code, the expression, and the update code
   • Colon
     • in the for statement that iterates over an array or a collection.
   • Comma
     • separate arguments in method declarations
   • Period
     • separate package names from subpackages and type names, separate a field or method from a reference variable.

3. Primitives

   • Data type
   • 8 types
     • 6 (byte, short, int, long, float, double) represent numbers and have unique ranges
     • char
       • can contain a single unicode character
     • boolean
       • can contain false or true

4. Variables

   • Data placeholders
   • Data types and identifiers

5. Constants

   • Variables whose values cannot be changed
   • "final" keyword

6. Literals

   • To assign values to variables in a program
   • Integer literals, floating-point literals, character literals, boolean literals