1. 3.1 Documentation &
Java Language Elements

2. 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. 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 //

4. 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 the comments
@author, @version, @param, @return, etc

5. 3.1.4 Java API documentation

6. 3.1.5 Generating API docs for
classes using the javadoc tool

7. 3.2.2 Keywords
• Keywords form the Java
vocabulary
• The compiler is case-sensitive

8. 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

9. 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

10. 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.

11. 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

12. 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 -231 to 231 -1
• long – Signed whole numbers from -9x1018 to 9x1018 -1
• float – Decimal values up to 6 – 7 decimal places
• double – Decimal values up to 14 – 15 decimal places

13. 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

14. 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

15. 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;
}
Try to Identify!!!!!
public String getName() { 1. Object Data/Variable
return studentName;
2. Static Data/Variable
}
} 3. Local Data/Variable
4. Constants

16. 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

17. 3.5.2 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;
constructor grade = grd;
class }
public void changeGrade(String grd) {
grade = grd;
method }
public String getName() {
return studentName;
}
}

18. 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

19. 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

20. Individual activity & Lab Work
• Possible Lab Schedule every:
– Monday, 15.00-16.50 or
– Friday, 14.30 - 15.20 (PUSKOM-FTUI)
• TODO LIST (finished before next session):
– Read through the online curriculum
– Take the module exam 1 – 3 (Start: Thursday)
– Do LABs:
• 3.1.6.1 Insert Documentation for Classes in the JBANK Application
• 3.1.6.2 Generate API Docs for JBANK Classes with the javadoc Tool
• 3.5.1 Define Variables
• 3.5.9 Apply Access Modifiers
• 3.6.1 Use of Constructors
• 3.8.1 Create the Classes for Phase I of the JBANK Application
Note: Red bold color is obligatory to be submitted to ECourse System!