4 programming-using-java intro-tojava20102011

Using Java
MINISTRY OF EDUCATION & HIGHER EDUCATION
COLLEGE OF SCIENCE AND TECHNOLOGY
KHANYOUNIS- PALESTINE

 First Program in Java
 Discussion of the main concepts
 Install the JDK and JCreator
 Memory Concepts and DataTypes
 Variables and Identifiers
 Arithmetic Operations
 Emank X Mezank
2Presented & Prepared by: Mahmoud R. Alfarra

 Computer programmers create applications
by writing computer programs.
 Your e-mail application helps you send and receive e-mail
 yourWeb browser lets you view Web pages fromWeb sites
around the world.
 A Java application is a computer program
that executes when you use the java
command to launch the JavaVirtual Machine
(JVM).

 Let us consider a simple application that
displays a line of text using Java command.

 Every program in Java consists of at least one
class declaration that is defined by the
programmer.
 These are known as programmer-defined
classes or user-defined classes.

 Java class declarations normally contain one
or more methods.
 For a Java application, exactly one of the
methods must be called main and must be
defined as shown
It is a syntax error if braces do not occur in matching
pairs

 Instructions perform an action namely, to
print the string of characters contained
between the double quotation marks.
 We refer to characters between double
quotation marks simply as strings.

 Method System.out.println displays a line of text in
the command window.
 The string in the parentheses is the argument to the
method.
 Method print displays one line of text in the
command window and position the cursor next
the last character.
 Println position the output cursor at the
beginning of the next line in the command.

 begins with // or between /* */, indicating
that the remainder of the line is a comment.
 The Java compiler ignores comments.

Java is case sensitive. Not using the proper uppercase and
lowercase letters for an identifier normally causes a
compilation error.
It is an error for a public class to have a file name that is not
identical to the class name (plus the .java extension) in terms
of both spelling and capitalization.
Omitting the semicolon at the end of a statement is a syntax
error.

 From the sun site
▪ http://java.sun.com/javase/downloads/index.jsp.
 download jdk-6-windows-i586.exe
 Setup normally (next then next …)
 But be care where it will be installed in your
PC

 From the site of Jcreator or my web site
▪ http://www.jcreator.com/
▪ Staff.cst.ps/mfarra
 Download the JCreator Pro
 And then trace the following slides to setup …

‫إعداد‬/‫أ‬.
‫رفيق‬ ‫حممود‬
‫ا‬‫ر‬‫الف‬ ‫محدي‬
2010-
2011

4 programming-using-java intro-tojava20102011

7
Install the JDK and JCreator on your PC at home,
and then write a program that prints your name, ID,
GPA, addressHW 4.1

 Identifiers are names used to identify
variables, methods, classes …
 An identifier consist of letters,numbers, _ , $
 But must:
 Begin with letter.
 not contain space.
 not a reserved word

 A variable is a location in the computer's
memory where a value can be stored for use
later in a program.
 All variables must be declared with a name
and a type before they can be used.
Data type Identifiers

 Data types in Java are divided into two
categories primitive types and reference.
 A primitive-type variable can store exactly
one value of its declared type at a time.
 Every variable has a name, a type, a size and
a value.

0 0 0 1 1 1 0 0 ‫الذكرة‬ ‫من‬‫مقطع‬
‫يتم‬‫التعريف‬ ‫هذا‬ ‫بمجرد‬
‫الذاكرة‬ ‫في‬ ‫مساحة‬ ‫تخصيص‬
‫يناس‬ ‫بحجم‬‫بيانات‬ ‫لتخزين‬‫ب‬
‫اد‬‫ر‬‫امل‬‫النوع‬
Type1 x = 28 ; // ‫سعتها‬ ‫الذاكرة‬ ‫في‬ ‫مساحة‬‫تخصيص‬ ‫سيتم‬1‫بايت‬
Type2 y; // ‫سعتها‬ ‫الذاكرة‬ ‫في‬ ‫مساحة‬‫تخصيص‬ ‫سيتم‬2‫بايت‬

TypeValues examplesSize
booleantrue, false1 Byte
char‘b’, ‘c’ , ‘t’, ‘5’, …2 byte
byte128, 0, 34, …1 byte
short32768, 67, 342 byte
int2147483648 , 7, 9, 0, …4 byte
long9223372036854775808, 878, …8 byte
float- 3.5, 234.56, …4 byte
double-2345.34, …8 byte

 Most programs perform arithmetic calculations.
 The arithmetic operators are

 Java applies the operators in arithmetic expressions
in a precise sequence determined by the following
rules of operator precedence:

Some common escape sequences

‫تعاىل‬ ‫هللا‬ ‫قال‬:
(ِ‫ج‬‫لل‬ِ‫ِب‬ ‫ج‬‫ن‬‫نو‬ِ‫ؤم‬ُ‫ي‬ ً‫ا‬‫وم‬‫ج‬‫ق‬ ُ‫د‬ِ‫ج‬‫َت‬ ‫ال‬ِ‫ر‬‫ر‬ِ‫خ‬‫ج‬‫أل‬‫ا‬ ِ‫وم‬‫ج‬‫الي‬‫ج‬‫و‬‫ج‬‫ن‬‫و‬‫و‬‫د‬‫روا‬ُ‫ي‬
ُ‫ه‬‫ج‬‫ل‬‫سو‬‫ج‬‫ر‬‫ج‬‫و‬ ‫ج‬‫ج‬‫الل‬ َّ‫حاد‬ ‫ن‬‫ج‬‫م‬)

Introduction
to OOP

4 programming-using-java intro-tojava20102011

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