2. 2.1.1 Procedural versus OOP
languages
• Procedural programming involves
creating a sequence of instructions
• OOP uses a collection of
interacting objects
• Functions are logically grouped,
making enhancements easy
• OOP can model human problem-
solving
3. 2.1.2 Basic Java terminology
Object. contains data and instructions
Class. blueprint for an object
Attribute. describe the state of objects
Data Type. describes what kind of information a
certain attribute is
Behavior. describe what objects can do
Method. a set of instructions
Inheritance. Some objects derive attributes and
behaviors from other objects
Encapsulation. Combining data and methods
together
4. 2.2 What are Objects? 2.2.1
Introduction to objects
• Anything tangible or abstract that is
relevent
• Objects can have attributes and
behaviors
• Attributes describe the object
• Behaviors describe what the object
can do
5. 2.2.2 Classification of objects
• User Interface objects
– Objects that the user interacts directly
with
• Operating environment objects
– Provide services to other components
• Task Related objects
– Documents, multimedia, problem
domain
6. 2.2.3 Objects - identifying, defining,
creating and operating on
• Identifying – Requires needs assessment
• Defining – Classification, relationships,
operations. The class keyword
• Creating – The constructor and the new
keyword
• Operating – Using an object’s methods
7. 2.2.7 Encapsulation
• To hide the details, package together
• Access modifiers – public, private
and protected
8. 2.2.8 Object relationships
• Association
– Objects know
about each other
• Whole-part
– Existance of an
object relies on
another
• Inheritance
– Attributes &
behaviors can be
inherited
10. 2.2.10 Object mutability and
destruction
• Some object attributes should be immutable, or
unchangable
• To make an item immutable, use the final
keyword
• The JVM automatically releases memory when
objects are no longer required
• The garbage collector will reclaim memory by
objects that are no longer referenced
• Garage collection is not controllable
11. 2.3.1 Modeling languages and
symbols
• Unified Modeling
Language (UML)
standardizes symbols
& terminology for
diagramming objects
12. 2.3.2 Basic Class symbol
• Rectangle represents a class
of objects
• 3 compartments: Name,
attributes , and operations or
methods
• Symbols indicate
accessibility
13. 2.4.1 Class definition
•Defined by using
public class Person {
private String name; the class keyword
public Person(String theName) { •Public classes
name = theName; defined in separate
}
} files
•Filename must be
the same as the
class name
14. 2.4.2 Creating objects
• Constructor methods are called when an
object is created
• All object data is stored in memory
• Variables are a reference to the memory
location
15. 2.4.3 Object methods
• Mutator – Changes object data
• Accessor – Retrieves object data
• Methods with no arguments
• Methods that require arguments
• Method return values – Provide a result to
the caller
16. 2.5.1 System class
• Data stored by an object is member data
• Data present in an object’s methods is
called local or temporary data
• Java.lang.System is a pre-defined object
that can be used to perform system tasks
System.out.println(“Hello World!”);
