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

Introduction to
Java Programming
Y. Daniel Liang
Edited by Hoàng Văn Hậu – VTC Academy – THSoft co.,ltd
https://play.google.com/store/apps/developer?id=THSoft+Co.,Ltd

Introduction
 Course Objectives
 Organization of the Book

VTC Academy THSoft Co.,Ltd 2

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)


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


Session 01 Introduction to Java
and Eclipse
 What Is Java?
 Getting Started With Java Programming
– Create, Compile and Running a Java
Application


What Is Java?
 Java language programming market


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)

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


Java IDE Tools
 Forteby Sun MicroSystems
 Borland JBuilder

 Microsoft Visual J++
 NetBean by Oracle
 IBM Visual Age for Java
 Eclipse by Sun MicroSystems


Getting Started with Java
Programming
A Simple Java Application
 Compiling Programs
 Executing Applications


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!");
}
}

Source Run
NOTE: To run the program,
install slide files on hard
VTC Academy THSoft Co.,Ltd
disk. 11

Creating and Compiling Programs
Create/Modify Source Code

 On command line
– javac file.java
Source Code

Compile Source Code
i.e. javac Welcome.java

If compilation errors

Bytecode

Run Byteode
i.e. java Welcome

Result

If runtime errors or incorrect result


Executing Applications
 On command line
– java classname

Bytecode

Java Java Java
Interpreter Interpreter Interpreter
...
on Windows on Linux on Sun Solaris


Example
javac Welcome.java

java Welcome

output:...


Compiling and Running a Program
Where are the files
Welcome.java
stored in the
c:example directory?
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


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


Comments

Eclipse shortcut key:
Ctrl + Shift + C
Ctrl + Shift + /
Ctrl + /

Package


Keywords (reserved words)
http://en.wikipedia.org/wiki/List_of_Java_keywords


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) { Class block
System.out.println("Welcome to Java!"); Method block
}
}


Data Types
byte 8 bits
short 16 bits
int 32 bits
long 64 bits
float 32 bits
double 64 bits
char 16 bits


Constants
final datatype CONSTANTNAME = VALUE;

final double PI = 3.14159;
final int SIZE = 3;


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)


Arithmetic Expressions
3 4x 10 ( y 5)( a b c) 4 9 x
9( )
5 x x y

is translated to

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


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


Increment and
Decrement Operators
suffix
x++; // Same as x = x + 1;
prefix
++x; // Same as x = x + 1;
suffix
x––; // Same as x = x - 1;
prefix
––x; // Same as x = x - 1;


Increment and
Decrement Operators, cont.
int i=10; Equivalent to
int newNum = 10*i;
int newNum = 10*i++;
i = i + 1;

int i=10; Equivalent to
i = i + 1;
int newNum = 10*(++i);
int newNum = 10*i;


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

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


Declaring Variables
int 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;


if ... Else


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.”
Source Run


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


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
3 4x 10 ( y 5)( a b c) 4 9 x
9( )
5 x x y


Actions on Eclipse
 Problem ax + b = 0
 Problem ax^2 + bx + c = 0

 Input data by user. (JOptionPane)


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

 Captions
 Members


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