Transcript java command

MINISTRY OF EDUCATION & HIGHER EDUCATION
COLLEGE OF SCIENCE AND TECHNOLOGY
KHANYOUNIS- PALESTINE
Using Java
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First Program in Java
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Discussion of the main concepts
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Install the JDK and JCreator
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Memory Concepts and Data Types
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Variables and Identifiers
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Arithmetic Operations
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Emank X Mezank
Presented & Prepared by: Mahmoud R. Alfarra
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Computer programmers create applications
by writing computer programs.
 Your e-mail application helps you send and receive e-mail
 your Web browser lets you view Web pages from Web sites
around the world.
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A Java application is a computer program
that executes when you use the java
command to launch the Java Virtual Machine
(JVM).
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Let us consider a simple application that
displays a line of text using Java command.
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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.
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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
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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.
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Method System.out.println displays a line of text in
the command window.
 The string in the parentheses is the argument to the
method.
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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.
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begins with // or between /* */, indicating
that the remainder of the line is a comment.
The Java compiler ignores comments.
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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.
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From the sun site
▪
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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
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From the site of Jcreator or my web site
▪
▪
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http://www.jcreator.com/
Staff.cst.ps/mfarra
Download the JCreator Pro
And then trace the following slides to setup …
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‫إعداد ‪ /‬أ‪.‬‬
‫حممود رفيق‬
‫محدي الفرا‬
‫‪-2010‬‬
‫‪2011‬‬
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HW 4.1
Install the JDK and JCreator on your PC at home,
and then write a program that prints your name, ID,
GPA, address
Identifiers are names used to identify
variables, methods, classes …
An identifier consist of letters,numbers, _ , $
But must:
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Begin with letter.
not contain space.
not a reserved word
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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
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Data types in Java are divided into two
categories primitive types and reference.
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A primitive-type variable can store exactly
one value of its declared type at a time.
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Every variable has a name, a type, a size and
a value.
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‫سيتم تخصيص مساحة في الذاكرة سعتها ‪ 1‬بايت ‪Type1 x = 28 ; //‬‬
‫;‪Type2 y‬‬
‫سيتم تخصيص مساحة في الذاكرة سعتها ‪ 2‬بايت ‪//‬‬
‫بمجرد هذا التعريف يتم‬
‫تخصيص مساحة في الذاكرة‬
‫لتخزين بيانات بحجم يناسب‬
‫النوع املراد‬
‫مقطع من الذكرة‬
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‫‪0‬‬
‫‪0‬‬
‫‪1‬‬
‫‪1‬‬
‫‪1‬‬
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Size
Values examples
Type
1 Byte
true, false
boolean
2 byte
‘b’, ‘c’ , ‘t’, ‘5’, …
char
1 byte
128, 0, 34, …
byte
2 byte
32768, 67, 34
short
4 byte
2147483648 , 7, 9, 0, …
int
8 byte
9223372036854775808, 878, …
long
4 byte
- 3.5, 234.56, …
float
8 byte
-2345.34, …
double
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Most programs perform arithmetic calculations.
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The arithmetic operators are
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Java applies the operators in arithmetic expressions
in a precise sequence determined by the following
rules of operator precedence:
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Some common escape sequences
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‫قال هللا تعاىل‪:‬‬
‫ِ‬
‫ِ‬
‫(ال جَِت ُد قجوماً ي ِ‬
‫ؤمنو جن ِِب جِ‬
‫لل جواليجوم األجخر ِر يُروا ودو جن‬
‫ُ‬
‫جمن َّ‬
‫اللج جوجرسولجهُ)‬
‫حاد ج‬
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Introduction
to OOP
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