bai giang java co ban - java cơ bản - bai 1

Introduction toJava Programming

Y. Daniel LiangEdited by Hoàng Văn Hậu – VTC Academy – THSoft co.,ltd

https://play.google.com/store/apps/developer?id=THSoft+Co.,Ltd

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Introduction

Course Objectives Organization of the Book

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Course Objectives Upon completing the course, you will understand

– Create, compile, and run Java programs

– Primitive data types

– Java control flow

– Methods– Arrays (for teaching Java in two semesters, this could be the end)

– Object-oriented programming

– Core Java classes (Swing, exception, internationalization, multithreading, multimedia, I/O, networking, Java Collections Framework)

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Course Objectives, cont.

You will be able to – Develop programs using Eclipse IDE– Write simple programs using primitive data

types, control statements, methods, and arrays.– Create and use methods– Write interesting projects

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Session 01 Introduction to Java and Eclipse

What Is Java? Getting Started With Java Programming

– Create, Compile and Running a Java Application

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What Is Java? Java language programming market

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History James Gosling and Sun Microsystems

Oak

Java, May 20, 1995, Sun World

HotJava – The first Java-enabled Web browser

JDK Evolutions

J2SE, J2ME, and J2EE (not mentioned in the book, but could discuss here optionally)

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Characteristics of Java Java is simple

Java is object-oriented

Java is distributed

Java is interpreted

Java is robust

Java is secure

Java is architecture-neutral

Java is portable

Java’s performance

Java is multithreaded

Java is dynamic

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Java IDE Tools Forte by Sun MicroSystems Borland JBuilder

Microsoft Visual J++

NetBean by Oracle

IBM Visual Age for Java

Eclipse by Sun MicroSystems

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Getting Started with Java Programming

A Simple Java Application

Compiling Programs

Executing Applications

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A Simple Application

Example 1.1//This application program prints Welcome//to Java! package chapter1;

public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); }}

RunRunSourceSource

NOTE: To run the program, install slide files on hard disk.

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Creating and Compiling Programs

On command line– javac file.java

Source Code

Create/Modify Source Code

Compile Source Code i.e. javac Welcome.java

Bytecode

Run Byteode i.e. java Welcome

Result

If compilation errors

If runtime errors or incorrect result

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Executing Applications

On command line– java classname

JavaInterpreter

on Windows

JavaInterpreter

on Sun Solaris

JavaInterpreteron Linux

Bytecode

...

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Example

javac Welcome.java

java Welcome

output:...

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Compiling and Running a Program

Where are the files stored in the directory?

c:\example

chapter1 Welcome.class

Welcome.java

chapter2

.

.

.

Java source files and class files for Chapter 2

chapter19 Java source files and class files for Chapter 19

Welcome.java~

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Anatomy of a Java Program Comments Package Keywords Variables – Data type Operators Control flow If else statement

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Comments

Eclipse shortcut key:Ctrl + Shift + C

Ctrl + Shift + /

Ctrl + /

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Package

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Keywords (reserved words)

http://en.wikipedia.org/wiki/List_of_Java_keywords

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Blocks

A pair of braces in a program forms a block that groups components of a program.

public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } }

Class block

Method block

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Data Types

byte 8 bits

short 16 bits

int 32 bits

long 64 bits

float 32 bits

double 64 bits

char 16 bits

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Constants

final datatype CONSTANTNAME = VALUE;

final double PI = 3.14159;

final int SIZE = 3;

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Operators

+, -, *, /, %, ++, --, +=, -=, *=, /=, ^, &, |

5/2 yields an integer 2.

5.0/2 yields a double value 2.5

5 % 2 yields 1 (the remainder of the division)

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Arithmetic Expressions

)94

(9))(5(10

5

43

y

x

xx

cbayx

is translated to

(3+4*x)/5 – 10*(y-5)*(a+b+c)/x + 9*(4/x + (9+x)/y)

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Shortcut Assignment Operators

Operator Example Equivalent

+= i+=8 i = i+8

-= f-=8.0 f = f-8.0

*= i*=8 i = i*8

/= i/=8 i = i/8

%= i%=8 i = i%8

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Increment andDecrement Operators

x++; // Same as x = x + 1;

++x; // Same as x = x + 1;

x––; // Same as x = x - 1;

––x; // Same as x = x - 1;

suffix

prefix

suffix

prefix

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Increment andDecrement Operators, cont.

int i=10; int newNum = 10*i++;

int newNum = 10*i; i = i + 1;

Equivalent to

int i=10; int newNum = 10*(++i);

i = i + 1; int newNum = 10*i;

Equivalent to

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Variables

// Compute the first arearadius = 1.0;area = radius*radius*3.14159;System.out.println("The area is “ + area + " for radius "+radius);

// Compute the second arearadius = 2.0;area = radius*radius*3.14159;System.out.println("The area is “ + area + " for radius "+radius);

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Declaring Variablesint x; // Declare x to be an // integer variable;

double radius; // Declare radius to // be a double variable;

char a; // Declare a to be a // character variable;

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if ... Else

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Displaying Text in a Message Dialog Box

you can use the showMessageDialog method in the JOptionPane class. JOptionPane is one of the many predefined classes in the Java system, which can be reused rather than “reinventing the wheel.”

RunRunSourceSource

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Actions on Eclipse

Development environment– Copy folder: Java_setup_thsoft– Install JDK– JAVA_HOME=path_to_jre– Install Eclipse (copy folder only)

Create workspace Create simple project

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Actions on Eclipse

Create, build, run welcome.java and welcomeBox.java

Rewrite demo Calcule this expression with a = b = c = 2.5;

x = y = z = 8.7

)94

(9))(5(10

5

43

y

x

xx

cbayx

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Actions on Eclipse

Problem ax + b = 0 Problem ax^2 + bx + c = 0

Input data by user. (JOptionPane)

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Action on class

Teacher – hauc2@yahoo.com– 0984380003– https://play.google.com/store/search?q=thsoft+co&c=apps

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