Programming Concepts

Programming Concepts

1. Unicode

   • used in Java - contains all character in all languages

2. Separators

   • ( ) used for arguments, operator precedence, narrowing conversation, loops
   • { } used for declarations, blocks of statement, array initialization
   • [ ] used for array declaration and value dereferencing
   • ; used to terminate statements
   • : used in 'for' statements for an array or collection
   • , used to separate arguments in method declaation
   • . used to separate packages and subpackages and fields/methods from variable
   • < > used to pass parameter to parameterized types

3. Primitives (a data type)

   • byte, short, int, long, float, double, char, boolean
   • not as 'expensive' as objects

4. Variables

   • Reference types references an object
   • Primitive type holds a primitive
   • Name must begin with a letter, not be a keyword, and be unique
     • See page 33 for list of keywords
   • Declare a variable by putting the type then the name. Ex: int count;
     • Assigning a value: int count = 0;
   • Constants = variables whose values can't be changed
     • use keyword 'final' in front of variable type. Ex: final int COUNT = 0;
     • all UPPERCASE names separated by underscore

5. Literals = source code representation of a value

   • only primitive types discussed here
   • Integer Literals
     • can be written as base 10, base 16 or base 8 decimals
       • Base16: begin with 0x or 0X
         • Base 8: begin with 0
     • Only used for byte, short, int, long
       • for type 'long', end the value with an 'L'
     • Can separate numbers for readability with underscores
       • Ex: 1000000 or 1_000_000
   • Floating-Point Literals
     • Contain: a whole number, a decimal point, a fraction part, and an optional exponent
       • f or F after the value indicates a float
         • d , D or writing nothing indicates a double
   • Character Literals
     • A unicode character or escape sequence enclosed in single quotes
       • Ex: 'a', 'C', '\t'
   • Boolean Literals
     • Can be true or false