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Object Oriented
Programming (2)
Java Programming (1)
Lecturer:
Eng. Mohamed Adam Isak
PH.D Researcher in Computer Science,
Sudan
M.Sc. and B.Sc. of Information
Technology Engineering, Libya
Lecturer in Imam Shafi’i, University of
Somalia and Mogadishu university
Website: WWW.ENGMAISAK.COM
BlogSpot: WWW.ENGMAISAK.BLOGSPOT.COM
E-mail: [email protected].
Tel:0615648915
Book Chapters
– Chapter 1 The history and evolution of JAVA
– Chapter 2 An overview of Java
– Chapter 3 Data Types, variables and arrays
– Chapter 4 Operators
– Chapter 5 Control Statements
– Chapter 6 Introducing classes
– Chapter 7 a closer look at methods and classes
3
Book Chapters, cont.
– Chapter 8 Inheritance
– Chapter 9 Packages and interfaces
– Chapter 10 Exception handling
– Chapter 16 Strings
– Chapter 17 Event handling
And more others
4
Chapter 1
The history and evolution of JAVA
AN OVERVIEW OF COMPUTERS & PROGRAMMING LANGUAGES
GOALS
• To understand the activity of programming
• To learn about the architecture of computers
• To learn about level of programming languages
• To become familiar with your computing
environment and your compiler
What is Programming?
• Computer programming
– the art and science of designing and writing
computer programs.
• Computer program
– a sequences of instructions written in a
programming language to achieve a task/to
solve a problem.
What is a computer?
• Hardware
– the physical, tangible parts of a computer
– keyboard, monitor, disks, wires, chips, etc.
• Software
– programs and data
– a program is a series of instructions
• A computer requires both hardware and
software
• Each is essentially useless without the other
Computer Organization
Computer System Organization
Hardware
•CPU
•Main Memory (RAM)
•Secondary Storage
•I/O Device
Software
•System Programs
•Application Programs
Hardware Components
of a Computer
Hardware Components
of a Computer – motherboard
adapter cards
processor chip
memory chips
memory slots
Expansion
slots for
adapter cards
motherboard
Hardware Components of a Computer
CPU
Brain of the
computer, most
expensive, the
faster computer.
CPU
components–
control unit,
program counter,
register instruction,
arithmetic logic
unit, accumulator.
RAM
Temporary memory,
volatile, directly
connected to the
CPU, using
memory cells unit.
Hardware Components of a Computer
SECONDARY STORAGE
•Provides permanent storage for
information.
•Examples of secondary storage:
•Hard disks
•Floppy disks
•Zip disks
•CD-ROMs
•Tapes.
RAM vs. Secondary Storage
• Primary memory
–
–
–
–
–
volatile
Fast
Expensive
Low capacity
Works directly with the processor
• Secondary Storage
–
–
–
–
–
Nonvolatile
Slow
Cheap
Large capacity
Not connected directly to the processor
Hardware Components of a Computer
INPUT DEVICES
Sheet-fed
Hardware Components of a Computer
OUTPUT DEVICES
CPU and Main Memory
Central
Processing
Unit
Primary storage area
for programs and data
that are in active use
Synonymous with
RAM
Main
Memory
Chip that executes
program commands
E.g..
Intel Pentium 4
Sun ultraSPARC III
Secondary Memory Devices
Secondary memory
devices provide
long-term storage
Hard disks
Floppy disks
USB drives
Writable CDs
Writable DVDs
Tapes
Central
Processing
Unit
Information is moved
between main memory
and secondary memory
as needed
Hard Disk
Main
Memory
Floppy Disk
Input / Output Devices
Monitor
Keyboard
Monitor screen
Keyboard
Mouse
Joystick
Bar code scanner
Touch screen
Central
Processing
Unit
I/O devices facilitate
user interaction
Hard Disk
Main
Memory
Floppy Disk
Hardware
• Imagine that you are using a computer to
write a letter.
– Where is the is the word processor program that
you are running located?
– Where are the characters you have typed?
Software Categories
• System Software
– Systems programs keep all the hardware and software
running together smoothly
– The most important system software is the operating
system (OS)
– controls all machine activities
– provides the user interface to the computer
– manages resources such as the CPU, memory & I/O
– Windows XP, Unix, Linux, Mac OS
• Application Software
– generic term for any other kind of softwares
– word processors, Spreadsheets, Web browsers, games
Digital Information
• Computers store all information digitally:
–
–
–
–
–
–
numbers
text
graphics and images
video
audio
program instructions
• In some way, all information is digitized broken down into pieces and represented as
numbers
Representing Text Digitally
• For example, every character is stored as a
number, including spaces, digits, and punctuation
• Corresponding upper and lower case letters are
separate characters
Hi, Heather.
72 105 44 32 72 101 97 116 104 101 114 46
American Standard Code for Information
Interchange (ASCII)
The ASCII data set  128 characters (0 until 127)
Character A in ASCII  01000001
p. 4.15 Fig. 4-16
Next
Binary Numbers
• Once information is digitized, it is
represented and stored in memory using the
binary number system
• A single binary digit (0 or 1) is called a bit
• A single bit can represent two possible
states, like a light bulb that is either on (1)
or off (0)
• Permutations of bits are used to store values
Memory
9278
9279
9280
9281
9282
9283
9284
9285
9286
Main memory is divided
into many memory
locations (or cells)
Each memory cell has a
numeric address, which
uniquely identifies it
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Storing Information
9278
9279
9280
9281
9282
9283
9284
9285
9286
10011010
Each memory cell stores a
set number of bits (usually
8 bits, or one byte)
Large values are
stored in consecutive
memory locations
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Storage Capacity
• Every memory device has a storage capacity,
indicating the number of bytes it can hold
• Capacities are expressed in various units:
Unit
Symbol
Number of Bytes
kilobyte
KB
210 = 1024
megabyte
MB
220 (over 1 million)
gigabyte
GB
230 (over 1 billion)
terabyte
TB
240 (over 1 trillion)
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Language Levels
• Levels of programming language levels:
– machine language
– assembly language
– high-level language
• Each type of CPU has its own specific
machine language
• The other levels were created to make it
easier for a human being to read and write
programs
29
Programming Languages
 Machine language
101101100110 011011010
 Assembly language
iload intRate
bipush 100
if_icmpgt intError
 High-level language
if (intRate > 100) . . .
Programming Languages
• Each type of CPU executes instructions only in a
particular machine language
• A program must be translated into machine
language before it can be executed
• A compiler is a software tool which translates from
high level language into a specific machine
language
• An assembler translates from assembly language
into a specific machine language
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Programming Languages
Language
Description
Examples
Interpreter
Machine
Instruction in 0
and 1 bits
0111000011000 None
001
Assembly
Instruction in
mnemonic code
LOAD 3
STOR 4
ADD
High-level
Similar to human sum = 4 + 3;
language,
FORTRAN,
COBOL, Pascal,
C, C++, Java…
assembler
Pengkompil &/
interpreter
Java’s Lineage (Family)
• Java is related to C++, which is a direct
descendant of C.
• Much of the character of Java is inherited
from these two languages.
• From C, Java derives its syntax. Many of
Java’s object oriented features were
influenced by C++
The Birth of Modern
Programming: C
• The creation of C was a direct result of the need
for a structured, efficient, high-level language that
could replace assembly code when creating
systems programs.
• As you probably know, when a computer language
is designed, trade-offs are often made, such as the
following:
– Ease-of-use versus power
– Safety versus efficiency
– Rigidity versus extensibility
C++: The Next Step
• During the late 1970s and early 1980s, C became the
dominant computer programming language, and it is still
widely used today.
• Since C is a successful and useful language, you might ask
why a need for something else existed.
• The answer is complexity. Throughout the history of
programming, the increasing complexity of programs has
driven the need for better ways to manage that complexity.
C++ is a response to that need.
• Another reason was: Approaches to programming have
changed dramatically since the invention of the computer
The C# Connection
• The reach and power of Java continues to be felt in the
world of computer language development. Many of its
innovative features, constructs, and concepts have become
part of the baseline for any new language. The success of
Java is simply too important to ignore.
• Perhaps the most important example of Java’s influence is
C#. Created by Microsoft to support the .NET Framework,
C# is closely related to Java. For example, both share the
same general syntax, support distributed programming, and
utilize the same object model. There are, of course,
differences between Java and C#, but the overall “look and
feel” of these languages is very similar
How Java Changed the Internet
• The Internet helped catapult Java to the forefront
of programming, and Java, in turn, had a profound
effect on the Internet.
• In addition to simplifying web programming in
general, Java innovated a new type of networked
program called the applet that changed the way the
online world thought about content.
The Java Programming Language
• Created by Sun Microsystems, Inc.
 introduced in 1995 and it's popularity has
grown quickly since
 Rich library
 Platform-independent ("write once, run
anywhere") or architecture-neutral
The Creation of Java
• Java was conceived by James Gosling, Patrick Naughton,
Chris Warth, Ed Frank, and Mike Sheridan at Sun
Microsystems, Inc. in 1991.
• It took 18 months to develop the first working version. This
language was initially called “Oak,” but was renamed “Java”
in 1995.
• Between the initial implementation of Oak in the fall of 1992
and the public announcement of Java in the spring of 1995,
many more people contributed to the design and evolution of
the language.
• Bill Joy, Arthur van Hoff, Jonathan Payne, Frank Yellin, and
Tim Lindholm were key contributors to the maturing of the
original prototype.
Characteristics of Java
(1)
• Java is simple
(2)
• Java is architecture-neutral
• Java is object-oriented
• Java is portable
• Java is distributed
• Java’s performance
• Java is interpreted
• Java is dynamic
• Java is secure
40
JDK Editions
• Java Standard Edition (J2SE)
– J2SE can be used to develop client-side standalone
applications or applets.
• Java Enterprise Edition (J2EE)
– J2EE can be used to develop server-side applications such as
Java servlets and Java ServerPages.
• Java Micro Edition (J2ME).
– J2ME can be used to develop applications for mobile
devices such as cell phones.
This book uses J2SE to introduce Java programming.
41
Java IDE Tools
• Forte by Sun MicroSystems
• Borland JBuilder
• Microsoft Visual J++
• WebGain Café
• IBM Visual Age for Java
• Netbeans
• Eclips
NB. To learn how java codes can be ran using
42
command prompt is better
Becoming Familiar with your Computer
to use Java
•
•
•
•
•
•
•
Understand files and folders/directories
Locate the Java compiler/ Install J2SE
Set path & Java class path
Write a simple program (later)
Save your work
Compile & run
Use Dos Command Prompt or IDE
hello_example.java
public class hello_example
{
public static void main (String []
args)
{
System.out.println ("Amazing Hello from
your special friend Mohamed Adam Isak
!");
}
}
Hello_example
Executing using DOS Command
Java Program Elements
• A Java program is made up of class definitions.
• A class definition must contains a header and a
body.
• A class contains zero or more methods
• A method is a named section of code that also has
a header & body
– A method contains program statements
• Single-line (starts with //) and multi-line (enclosed
by /* and */) comments are used to document the
code
Java Program Structure
//
comments about the class
public class Hello
{
class header
class body
//Comments can be placed almost anywhere
}
47
Java Program Structure
//
comments about the class
public class MyProgram
{
//
comments about the method
public static void main (String[] args)
{
method body
method header
}
}
48
Compiling and Running





Type program into text editor
Save (file name must be similar to class name)
Open Dos Window
Change directory to saved file directory
Compile into byte codes
javac hello_example.java
 Execute byte codes
java hello_example
From Source Code to Running
Program
Hello_example.java
Hello_example.class
javac
java
The Edit-Compile-Test Loop
Java Translation
• The Java compiler translates Java source code into
a special representation called bytecode
• Java bytecode is not the machine language for any
traditional CPU
• Another software tool, called an interpreter,
translates bytecode into machine language and
executes it
• Therefore the Java compiler is not tied to any
particular machine
52
Java Translation
Java source
code
Java
compiler
Java
bytecode
Bytecode
interpreter
Machine
code
53
Types of Java Code Errors
1. Syntax errors
System.our.print("...");
System.out.print("Hello);
Detected by the compiler
1. Logic errors
System.out.print("Hell");
Detected (hopefully) through testing
2. Run-time errors
Occur during program running
How to Write , compile and Run java Program via
Command Prompt(CMD) in Windows
1. Download latest JDK 64bit or 86bit (jdk1.7.0_25 x64 OR jdk1.7.0_25 x86) &
install it.
2. Right click on Computer icon(desktop) and click properties
click Advance System Settings. click Environment Variables
In the system variables box click on Path ----Click Edit
In the variable value just ADD the following: C:\Program
Files\Java\jdk1.7.0_25\bin. ((it must be explored and assured whether the
installed folder of java is there or not)), Then, save every thing you've done by
clicking OK.
3. Now open CMD(windows key +R and type cmd & Enter)
4. Open the notepad program
5. Write your java program in the notepad and save it in your Home Directory. i.e.
C:/Users/usrername(currently you have logged in)
6. Now you can compile your java program by javac<space><filename.java> and
by typing java<space>filename you can run your java program.
**This process is also applicable for 86bit windows(7&8). Change is that you have
to download latest jdk 32bit. All the rest is same
Available jobs for
JAVA developers
Example 1.1
Example 1.2
Example 1.3
Example 1.4
www.engmaisak.com