3.1 Documentation & Java Language Elements

3.1.1 Purpose of documentation Assist the programmer with developing the program Assist other programers who wish to use or modify the program

3.1.2 Guidelines for documenting classes Block comments – Start with /* and end with */. Can occupy multiple lines Single line comments – The line starts with //

3.1.3 The javadoc parameters The javadoc program can create HTML documents from the comments in the program’s source file To create javadoc comments, use /** and */ Special tags can be imbedded in etc

3.1.4 Java API documentation

3.1.5 Generating API docs for classes using the javadoc tool

3.2.2 Keywords Keywords form the Java vocabulary The compiler is case-sensitive

3.2.3 Identifiers Labels assigned to data or storage addresses Rules for identifiers: –Any alphabetic character –First character must be a letter –Cannot contain space, % or # –Cannot be keywords

3.2.4 Use of braces, semicolons, commas, and white space A block is a collection of statements bounded by braces { } A statement consists of one or more lines of code, followed by a semicolon ; Commas are used to delineate data Whitespace is used to separate keywords and identifiers

3.3.1 Data storage introduction Registers – Memory in the CPU The Stack – Memory for methods and local variables The Heap – Memory to store objects Static – Stores data that will not change during the life of the program Constant – Values that never change.

3.4.1 Java language types Data type is the classification of forms of information Data type is declared using keywords Java is strongly typed

3.4.2 Java primitives boolean – true or false char – Stores a single UNICODE character byte – Signed whole numbers from -127 to +128 short – Signed whole numbers from -32,768 to +32,767 int - Signed whole numbers from to long – Signed whole numbers from -9x10 18 to 9x float – Decimal values up to 6 – 7 decimal places double – Decimal values up to 14 – 15 decimal places

3.4.3 Java references Objects are created in heap memory Programs use a variable that references the object The program acts on the object by using the reference

3.4.4 Data Object Data – Instance of a class, stored on the heap Static Class Data – Available before the object is created Local Data – Exists in methods, stored on the stack Constants – Data that will not change Variables – Holds a primitive or a reference to an object

3.4.4 Data (example) public class Student { private final String studentName; public static final int courseNumber = 12345; public String grade; public Student(String name, String grd) { studentName = name; grade = grd; } public void changeGrade(String grd) { grade = grd; } public String getName() { return studentName; } Try to Identify!!!!! 1.Object Data/Variable 2.Static Data/Variable 3.Local Data/Variable 4.Constants

3.5.2 Elements Class – Template or blueprint for object creation Method – A block of statements that control an object’s behavior Constructor – A special method that is called when the object is created Modifiers – private, public, protected, default, static, final

constructormethod class Elements public class Student { private final String studentName; public static final int courseNumber = 12345; public String grade; public Student(String name, String grd) { studentName = name; grade = grd; } public void changeGrade(String grd) { grade = grd; } public String getName() { return studentName; }

3.6.1 Five steps of object creation Declaration of a reference variable Default initialization Explicit initialization Execution of the constructor Assignment of object’s address to reference variable

3.6.3 Mutability, Garbage Collection & Finalizers Most data is mutable, and can be changed. To make it immutable, use the final keyword Garbage collection frees up memory occupied by unused objects. This process cannot be controlled Every object inherits a finalizer method, that will be executed when the object is released

Individual activity & Lab Work Possible Lab Schedule every: –Monday, or –Friday, (PUSKOM-FTUI) TODO LIST (finished before next session): –Read through the online curriculum –Take the module exam 1 – 3 (Start: Thursday) –Do LABs: Insert Documentation for Classes in the JBANK Application Generate API Docs for JBANK Classes with the javadoc Tool Define Variables Apply Access Modifiers Use of Constructors Create the Classes for Phase I of the JBANK Application3.8.1 Note: Red bold color is obligatory to be submitted to ECourse System!