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Learning Plan 6
Java Programming
Intro to Object Oriented
Programming
Object Oriented Programming (OOP)
• Up until this point, all of our programs contained
one class (Furniture, Admissions, etc.)
• For example:
public class HelloWorld
{
public static void main(String[] args)
{
System.out.println(“HelloWorld”);
}
}
public class HelloWorld
{
public static void main(String[] args)
{
System.out.println(“HelloWorld”);
}
}
• Our programs contained one class
• Each class (or each program) contained a main method
• We are now going to start adding additional classes to our
programs
• Our programs will contain more than one class
• Only one of the classes will contain a ‘main’ method …. The
rest do not.
Object Oriented Programming
• We are going to explore the OOP concept
• We’ve already been using it
• OOP allows for reusability of code
– Why reinvent the wheel?
• Consider the following code:
Object-Oriented Programming (OOP)
JOptionPane.showInputDialog(null, “Enter
Name”):
• We’ve used this code frequently
• There is a file called JOptionPane.java that has
been written and compiled for us (it became
JOptionPane.class)
• Every time we wanted to ask the user for
input, we REUSED the code from the
JOptionPane class
Object Oriented Programming
• Start with Head First Java book
• Might jump around slightly
• Basic OOP Concepts and more advanced
concepts
– We will discuss & use basic concepts in depth
– We will discuss and analyze advanced OOP
concepts but use more of the concepts in other
courses.
OOP
• Basic concepts include:
– Classes, objects, methods, instance
variables/properties, arguments, parameters,
instantiation, encapsulation
• Advanced Concepts:
– Inheritance superclass/subclass, overriding
methods, polymorphism, abstract classes,
interfaces
• Chapter 1 – read 2-3; 8-17
• Before you start
– Page 2 talks about the Java Virtual Machine (JVM)
Java is a “write once, run anywhere” programming
language.
– Allows programs to run on multiple devices
– Page 3 shows you that to compile a program, you
execute the ‘javac’ command and to run it you
start the JVM and execute the ‘java’ command
• Textpad does this automatically for us!!