01 intro tousingjava
DESCRIPTION
TRANSCRIPT
Problem Solvingwith OOPand Java
Problem Solving
with OOP
Welcome To
and Java
Who Should Learn Java?
Have you done some programming?
Do you want to learn Java?
Do you prefer stimulating dinner conversations over coffee to dry, dull, technical lectures?
Do you need this course to graduate?
Java?
© PIC 2012
Java?
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IDC3931 © PIC
What Is A Computer?
A computer is something that takes in information (input), processes it according to a set of instructions (program), and produces a result (output).
Computers communicate through a binary alphabet. The letters in this alphabet are ‘0’ and ‘1’. Everything else is made out of these ‘letters’ which are called bits.
Bits are represented in a computer by electrical signals: low voltage would mean a ‘0’ and higher voltage a ‘1’. Eight bits gathered together form one byte.
What Is JAVA?Java is a free, open-source, Object Oriented Programming (OOP) language – everything is contained inside classes and objects.
Java is portable – it can run on any machine with a Java Virtual Machine (JVM) installed.
No matter what computer you have, you can write the same Java programs.
How WE use Java
Source Code
Compiler
Java byteco
de
Virtual
Machines
Source Code
Compiler
Java bytecode
Virtual Machines
How WE use Java
source code
class file
Code Structure in Java
method 1statement
method 2statementstatement
Collection of Java files
contains many classes
A classaclass.java
contains many methods and variables
public class aclass{public void
method() {
}
}
What goes in the source file?
A source file (with the .java extension) holds one class definition. The class represents a piece of your program, although a very tiny application might need just a single class. The class must go within a pair of
curly braces
public class Bicycle {
}
class
The source file MUST have the same name as the class. For example, the Bicycle class must be stored in the Bicycle.java file.
A class is the blueprint from which individual objects are created.
What goes in a class?A class has one or more methods. In the Bicycle class, the pedal method will hold instructions for how the Bicycle should pedal. Your methods must be declared inside a class (in other words, within the
curly braces
public class Bicycle{
void pedal( ) {
}}
method
of the class).
A bicycle might have some methods such as: speedup(), break(), gear(), direction()…
What goes in a
method?Within the
curly braces public class Dog {void bark ( )
{
statement1;
statement2;
statement3;
}}statements
of a method, write your instructions for how that method should be performed. Method code is basically a set of statements, and for now you can think of a function or procedure.
public class Bicycle{
void pedal( ) {
}}
statement1;statement2;statement3;
One Blueprint Can Be Used To Help Build Different
Objects
Shape
rotate ( )playSound ( )
Square Triang
le
Circle Amoeba
This is called inheritance
EVERYTHINGis made from OBJECTS
Shape
rotate()playSound()
Object
equals()getClass()hashCode()toString()
Circle
doSomething()
This is the Object class from which ALL other objects are created.
What You Will Get Out Of Learning and Using
Java!Build your programming skills and confidence.
A thorough understanding of Object Oriented Programming.
Learn a language that can be run on any platform.
Learn how to work and program in groups.
Develop Graphical User Interfaces.
Where To Start
Setup Eclipse Classic
Write your first Java program
If you can, bring your laptops to class every lecture!