Java Study Notes

INFS2605 Study Notes

Chapter 10 – Thinking in Objects

* Immutable object = an object whose contents cannot be changed once the object has been created

* Immutable class has all private data fields and no public set methods

* A variable defined inside a method = local variable

* If a local variable has the same name as a class variable the LV takes precedence and the CV is hidden

* Method that is not depending on a specific instance should be defined as a static method

* The THIS keyword is the name of a reference that an object can use to refer to itself [used mainly in the constructor]

* Class abstraction is the separation of class implementation from the use of the class

* The details of implementation are encapsulated and hidden from the user = encapsulation

Chapter 11 – Inheritance and Polymorphism

* OO programming allows you to define new classes from existing classes = INHERITANCE by extended a class (subclass) from another class (superclass) then using a super constructor

* Methods can be overridden only if it is accessible (private method can be overridden)

* POLYMORPHISM = a variable of a supertype (from a super class) can refer to a subtype (from a sub class) object

Chapter 12 – GUI Basics

Chapter 15 – Abstract Classes and Interfaces

* Abstract methods are implemented in concrete subclasses (using the abstract modifier in the header)

* Abstract classes are like regular classes but you can not create instances of abstract classes

* A subclass can be abstract if its super class is not

* You cant create new instances of an AC but you can use the AC as data type (Employee[ ] employees = new Employee[ 10 ])

* An interface is a class-like construct that contains only constants and abstract methods

* Class names are NOUNS where as interface names may be adjectives (edible) or nouns

* Interface can extend one or more interfaces

Chapter 14 – Exception Handling and Text I/O...