21 Days:   Wk1 . Wk1Ref . Applts . Swing . Grph . D13-14 . D15-21 . D22-28   cc12:   Miscl . SQL . EJB . Vocab . (NotesHelp) . J2EE . Web   misl:   21 Days(src) . Dictionary(foldoc) . Unicode . Tables . Print . html   misl:   F.Allimant . Swing (J.H.University)

TERMS from Week 1. (There is a good glossary at end of Day2)
• An object is a self-contained element of a computer program that represents a related group of features and is designed to accomplish specific tasks. Objects are also called instances. (Day2.pg.37)
• A class is a template used to create an object. Every object created from the same class will have similar, if not identical, features. (pg.37)
• A instance variable defines an attribute of one particular object. (pg.40)
• A class variable defines an attribute of an entire class. (pg.40)
• Methods are groups of related statements in a class of objects that handle a task. They are used to accomplish specific tasks on their own objects and others, and are used in the way that functions are used in procedural programming. Instance methods, commonly just called methods, are used when working with an object of a class. Class methods apply to a class itself. (pg.41)
• Inheritance is a mechanism that enables one class to inherit all the behavior and attributes of another class. (pg.47)
• subclass - a class that inherits from another class. All attributes are inherited. (pg.47)
• superclass - the class that gives the inheritance to the subclass. A class can have only one superclass, but each class can have an unlimited number of subclasses. (pg.47)
• Object is the name of the class, at the top of the Java class hierarchy. (pg.48)
• Overriding is the procedure of giving a method, of a subclass, the same: name, return-type and argumentsas its superclass's method. (pg.52)
• A statement is one java command ending in a semicolon ';'. (Day3.pg.60)
• An expression is a statement that results in a value being produced, called the return value. (pg.60)
• A variable stores a number or some other type of information, for the program, while it is running.
  Java has three types of variables: (pg.61)
  1. Instance variables define an objects attributes. (See Day4)
  2. Class variables define the attributes of an entire class of objects. (See Day4)
  3. Local variables are used inside method definitions, or even smaller blocks. They can be used only while the method or block is being executed, and cease to exist afterward.
  Unlike other languages, Java does not have global variables (variables that can be used in all parts of the program.)
  Instance and class variables are used in replace of globals, to communicate information from one object to another.
• Prefix operator example: ++var1;  Postfix operator example: var2++;  (pg.76) (more info)
• Constructors are special methods for creating and initializing new objects. If the new object needs other objects to initialize itself, then the constructor creates those also. The constructor method(s) have the same name as the class. (pg.88)
• A block is a group of statements enclosed between a pair of curly braces, '{' and '}'. (pg.61)
• A Block Statement is a section of code that is enclosed by a pair of curly braces.  (pg.114)
• The scope of a variable (or other info) is the places in the code that the variable exists and may be used. When the section of code, that defined the scope of an item, finishes executing, then the item will no longer exist. (pg.138)
• A conditional is a programming statment that determines if a statment or block is to be run.
• A Method's Signature is the combination of its name and parameter list.
• Method Overloading provides several methods with the same name but different a parameter list.
• Interface - A set of methods for behavior beyond the class's. (?wording?).
• Package - A collection of classes and interfaces.

TERMS after Week 1. (started May/05/2004)
• Coordinate space - Any 2D area describable by x,y coordinates. (Day12)
• Gradient fill - A gradual shift of color, from point to point. (Day12)
• Acyclic gradient - The gradual color shift occurs once, pt to pt. (Day12.pg.318)
• Cyclic gradient - The gradual color shift occurs pt to pt and repeats. (Day12.pg.318)
• Endcap style - Defines how un-joined lines end. (Day12.pg.320)
• Juncture style - Defines how joined lines end. (Day12.pg.320)
• encapsulation - process of preventing variables from being visible to other classes. (Day15.pg.383)
• obj serialization (2) - Ability to read and write an object using streams. (Day18.pg.470)
• stream - An object that transports data. (Day18.pg.470)
• persistence - Ability of an object to exist and function outside its parent program. (Day18.pg.471)
• reflection - Way to find class name, return type, etc of an ojbect's class. (Day18.pg.478)
• Remote Method Invocation (RMI) - Effective way to write client / server aps. (Day18.pg.485)
• Networking - ability of computer connecting with each other and exchanging information. (Day19.pg.496)
• A JavaBean "is a software object that interacts with other objects according to a
  strict set of guidlines - the JavaBean Specification". (Day20.pg.523)
• Persistence is a functionality from Java, that an object can "store and retrieve its internal state".
• Encapsulation - Keeping a variable private and accessing it with a getter and setter. A good principle even when not building a bean.

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  Java Data Types


===WAYS TO SPECIFY TYPE...
(1) eight primitive types, (2) name of a class (data declared is an object), (3) name of an interface, (4) or an array.

===EIGHT PRIMITIVE DATA TYPES:
Four Integer types, two Floating-Point, char and boolean.

Tbl3.1.   The 8 Primitive Data Types  (pg.64)

byte   short   int   long   float   double   char   boolean

8 bits (1 byte)   16 bits (2 bytes)   32 bits (4 bytes)   64 bits (8 bytes)

-128 ... 127 -32,768 ... 32,767 +/-  2,147 M +/-  9,223,372,036 G 1.4E-45 ... 3.4E+38 4.9E-324 ... 1.7E+308 letters, numbers, and symbols true or false

===CHARACTER LITERALS

Tbl3.2.   Character Escape Codes  (pg.70)

\n   \t   \b   \r   \f   \\

New line   Tab   Backspace   Carriage return   Formfeed   Backslash

\'   \"   \d   \xd   \ud

Single quotation mark   Double quotation mark   Octal   Hexadecimal   Unicode character   (nothing for bell or vertical tab)

===OPERATOR PRECEDENCE  (pg.79, 80)

()  .  []	'()' used to group expresions; '.' used to access methods and variables within objects and classes (see day4); '[]' with arrays;
++  --  !  -  instanceof	The 'instanceof' operator returns 'true' or 'false'. Determines if the object is an instance of the named class or that class's subclasses. (see day4)
new  (type)expression	'new' for creating new instances of classes; '()' for casting a value to another type. (see day4)
*  /  %	Multiplication, division, modulus.
+  -	Addition, subtraction.
<<  >>  >>>	Bitwise left and right shift.
<  >  <=  >=	Relational comparison tests.
==  !=	Equality.
&	AND.
^	XOR.
|	OR.
&&	Logical AND.
||	Logical OR.
?  :	Shorthand for, if...then...else.
=  +=  -=  *=  /=  %=  ^=	Various assignments.
&=  |=  <<=  >>=  >>>=	More assignments.

===NOTES FOUND AFTER WEEK ONE **************************************************
-----Page 315: FLOATING POINT NUMBERS
- Three examples of casting to a float constant: 0.807F, 1F, 0F
- No Java class or method we work with takes hexadecimal arguments.

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B19 - Teach Yourself Java 2 in 21 Days. 2nd ed. Lemay and Cadenhead. © 2001.
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