The Language of Programming

The Language of Programming

1. Characters

   • There are many different character sets, all of varying sizes and suited for the needs of users in different regions
   • ASCII
     • Consists of 128 characters, each represented by 7 bits
     • Extended version of ASCII contains 256 characters, each represented by 8 bits
     • Java uses ASCII for most inputs
   • 8 bits = 1 byte. Storing and transmittng 8 bits is most efficient
   • Unicode
     • Attempts to include all characters in 1 set
     • There are various Unicode character encodings, so developers can use the one that they need
     • Java supports Unicode for comments, identifiers, and strings

2. Separators

   • () Parentheses
     • Indicate operator precedence in expressions
     • Contain arguments in method signature
     • Used in narrowing conversions
     • Used in loops to contain expressions to be evaluated
   • {} Braces
     • Used in declaration of types
     • Used in blocks of statements
     • Used to initialize arrays
   • [] are used in array initialization and array value dereferenceing
   • <> pass parameter to parametrized typed
   • ; terminates staments and separates parts of for statements
   • : is used in for statements that iterate over arrays or collections
   • , separates arguments in method declarations
   • . separates package names from subpackages and field or method from reference variable

3. Primitives

   • Primitives are data types
   • Numbers
     • 6 primitive data types represent numbers: byte, short, int, long, float, double
     • byte, short, int, and long all represent integers. Bytes as smallest, shorts are next smallest. Longs are largest
       • Numbers assigned to Long must have a suffix of "L"
       • Can all also be expressed in binary with "0B" prefix
       • You can use _ to separate digits in an integer literal
     • Float and double represent decimals. A double takes more space
       • Floating-point literals have a whole number part, a decimal point, a fraction part, and an optional exponent
   • char
     • A single Unicode character
       • Some character literals are escape sequences, used to express quotes, tabs, Unicode characters, etc.
   • boolean
     • true or false

4. Variables

   • Variables are data placeholders
   • Each variable must have a declared type.
     • Reference types: variable points to an objects
     • Primitive types: variable holds a primitive
   • Variables have a name (identifier)
     • It must begin with a java letter and cannot be a Java keyword, boolean, or null
       • A Java letter is any capital or lowercase letter, or $