lectre 1- java intro
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Java Programming
Java Basics
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Contents
Background Java Virtual Machine
Application & Applet
Class & Object
3 Principles of Object Oriented Programming
Start up Java
Variables & Assign
String & Character
Arithmetic Operator & Expression
Comment Array
Keywords
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Background / History
Sun Microsystems Inc.
James Gosling
1990, Green Project
1991, Develop the Language for Household Products => To
General Developing Language
Java
James Gosling, Arthur Van Hoff, Andy Bechtolsheim
Coffee Materials in Indonesia
Write once, Run everywhere
Spread Rapidly through WWW and Internet
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Byte Code and Java Virtual Machine
Existing Development Environment
Source
Code
Compiler(Pentium)
Compiler(PowerPC)
Compiler(SPARC)
Binary
File
Pentium
PowerPC
SPARC
Binary
File
Binary
File%cc Hello.c o Hello
% Hello
Binary CodeRun
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Byte Code and Java Virtual Machine
Java Development Environment
Java Compiler
(Pentium)
Java Compiler
(PowerPC)
Java Compiler
(SPARC)
Java
Interpreter
Pentium
PowerPC
SPARC
Java
Interpreter
Java
Interpreter
Java
Code
Java
ByteCode
(Independent on
Platform)
%javac Hello.java
Hello.class created
% java Hello
Byte CodeRun JVM
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Java Program
Java Application Program
Application
Program written in general programming
language
Applet
Program running in Web Browser Environment
Can be viewed by appletviewer or Web browser
with JVM
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Class and Object
Object
Memory Space to Define State and Operation
Instance of Class
Class Template of Creating Object
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3 Principles of Object Oriented Programming
Encapsulation
Control Access the data and method in program code
Inheritance
Inherit the data and methods of parent class
Polymorphism
Shape
Ellipse Rectangle Triangle
getArea()
getArea() getArea()getArea()
Shape Obj = new Ellipse();
Obj.getArea();
Which Area?
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Java Class Library
java.applet : Applet related java.awt : Abstract Window Toolkit
java.awt.event : Event process from awt component
java.awt.image : Image processing
java.beans : JavaBeans Component java.io : File or Network I/O Support
java.lang : Java Language Support
java.net : Network related functions
java.util : Utility function
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Java 2 SDK
Java 2 Software Development Kit (Java 2 SDK)
Java Application or Applet Development and
Running Environment
Java 2 Runtime Environment (JRE) Java Running Environment
Java 2 Standard Edition
Java 2 Micro Edition Java 2 Enterprise Edition
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Java Program Structure
In the Java programming language: A program is made up of one or more classes A class contains one or more methods A method contains program statements
These terms will be explored in detail throughout the course A Java application always contains a method calledmain
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Java Program Structure
public class MyProgram{
}
// comments about the class
class header
class body
Comments can be placed almost anywhere
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Java Program Structure
public class MyProgram{
}
// comments about the class
public static void main (String[] args){
}
// comments about the method
method headermethod body
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Start Java Application
Hello.java
class Hello {
public static void main(String args[]) {
System.out.println(Hello World);
}
% javac Hello.java
% java Hello
Compile
Run
hello.c
void main() {
printf(Hello World\n);
}
% cc hello.c o hello
% hello
Hello WorldResult
Java C
Class Name
Main method
Main Function
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Variable and Assign
Variable
Type
char 16bits Unicode character data
boolean Boolean Variable
byte 8 bits signed integer short 16 bits signed integer
int 32 bits signed integer
long 64 bits signed integer
float 32 bits signed floating point number
double 64 bits signed floating point number
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Variable and Assign
int num = 100;
long m = 21234234L
double type : .5 0.8 9e-2 -9.3e-5float type : 1.5e-3f;
Variable Declaration
type varName;
Value assign
varName = value;
float x, y, x;
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String and Character
String : sequence of character
String s = Enter an integer value: ;
Char c = A;
Concatenation Operator +
String s = Lincoln said: + \ Four score and seven years ago\ ;
Result :
Lincoln said: Four score and seven years ago
Unicode
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Arithmetic Operator
Operators
+ - * / %
+= -= *= /= %=
++ --
5 / 2
2 Why isnt it 2.5 ?5 % 2 14 / 2 24 % 2 0
count * num + 88 / val19 % count
j += 6; j = j + 6;
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Comment
Single Line Comment
int i = 10 ; //i is counter
Multiple Line Comment
/*
Some comments*/
Documentation Comment
/**
Documentation Comment
*/
Using javadoc Tool,
make document
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Arrays ( One Dimensional)
type VarName[]
Definition of One Dimensional Array
int ia[];
varName = new type[size]
Assign Range to One Dimensional Array
ia = new int[10];
type varName[] = new type[size]
Declaration of One Dimensional Array with Range
int ia[] = new int[10];
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Arrays ( One Dimensional)
varName.length
Number of elements in Array
Type varName[] = {e0, , en};
Initialization of One Dimensional Array
int j[] = {0, 1, 2, 3, 4, 5};
int k[];
K = j;
Example 1.15
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Arrays ( Multi-Dimensional)
type VarName[][];
Definition of Two Dimensional Array
float fa[][];
varName = new type[size1][size2];
Assign Range to Two Dimensional Array
fa = new float[2][3];
type varName[][] = new type[size1][size2];
Declaration of Two Dimensional Array with Range
float fa[] = new float[2][3];
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Arrays ( Two Dimensional)
varName.length
Number of elements in Multi-Dimensional Array
Type varName[][] = {{e00,
, e0n}, {e10,
,e1y}, {e20,
, e2z}};
Initialization of Multi-Dimensional Array
Example 1.16
varName[index].length
Number of elements in Each elements of Multi-Dimensional Array
Number of Raw
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Java Keywords
47 Java Keywordsabstract double int super
boolean else interface switch
break extends long synchronized
byte final native this
case finally new throwcatch float package throws
char for private transient*
class goto* protected try
const* if public void
continue implements return volatile
default import short while
do instanceof static
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