Bài giảng java cơ bản, bài 1/5

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

2. Introduction
 Course Objectives
 Organization of the Book
VTC Academy THSoft Co.,Ltd 2

3. 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)
VTC Academy THSoft Co.,Ltd 3

4. 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
VTC Academy THSoft Co.,Ltd 4

5. Session 01 Introduction to Java
and Eclipse
 What Is Java?
 Getting Started With Java Programming
– Create, Compile and Running a Java
Application
VTC Academy THSoft Co.,Ltd 5

6. What Is Java?
 Java language programming market
VTC Academy THSoft Co.,Ltd 6

7. 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)
VTC Academy THSoft Co.,Ltd 7

8. 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
VTC Academy THSoft Co.,Ltd 8

9. Java IDE Tools
 Forteby Sun MicroSystems
 Borland JBuilder
 Microsoft Visual J++
 NetBean by Oracle
 IBM Visual Age for Java
 Eclipse by Sun MicroSystems
VTC Academy THSoft Co.,Ltd 9

10. Getting Started with Java
Programming
A Simple Java Application
 Compiling Programs
 Executing Applications
VTC Academy THSoft Co.,Ltd 10

11. 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

12. 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
VTC Academy THSoft Co.,Ltd 12

13. Executing Applications
 On command line
– java classname
Bytecode
Java Java Java
Interpreter Interpreter Interpreter
...
on Windows on Linux on Sun Solaris
VTC Academy THSoft Co.,Ltd 13

14. Example
javac Welcome.java
java Welcome
output:...
VTC Academy THSoft Co.,Ltd 14

15. 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
VTC Academy THSoft Co.,Ltd 15

16. Anatomy of a Java Program
 Comments
 Package
 Keywords
 Variables – Data type
 Operators
 Control flow
 If else statement
VTC Academy THSoft Co.,Ltd 16

17. Comments
Eclipse shortcut key:
Ctrl + Shift + C
Ctrl + Shift + /
Ctrl + /
VTC Academy THSoft Co.,Ltd 17

18. Package
VTC Academy THSoft Co.,Ltd 18

19. Keywords (reserved words)
http://en.wikipedia.org/wiki/List_of_Java_keywords
VTC Academy THSoft Co.,Ltd 19

20. 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
}
}
VTC Academy THSoft Co.,Ltd 20

21. Data Types
byte 8 bits
short 16 bits
int 32 bits
long 64 bits
float 32 bits
double 64 bits
char 16 bits
VTC Academy THSoft Co.,Ltd 21

22. Constants
final datatype CONSTANTNAME = VALUE;
final double PI = 3.14159;
final int SIZE = 3;
VTC Academy THSoft Co.,Ltd 22

23. 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)
VTC Academy THSoft Co.,Ltd 23

24. 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)
VTC Academy THSoft Co.,Ltd 24

25. 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
VTC Academy THSoft Co.,Ltd 25

26. 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;
VTC Academy THSoft Co.,Ltd 26

27. 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;
VTC Academy THSoft Co.,Ltd 27

28. 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);
VTC Academy THSoft Co.,Ltd 28

29. 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;
VTC Academy THSoft Co.,Ltd 29

30. if ... Else
VTC Academy THSoft Co.,Ltd 30

31. 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
VTC Academy THSoft Co.,Ltd 31

32. 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
VTC Academy THSoft Co.,Ltd 32

33. 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
VTC Academy THSoft Co.,Ltd 33

34. Actions on Eclipse
 Problem ax + b = 0
 Problem ax^2 + bx + c = 0
 Input data by user. (JOptionPane)
VTC Academy THSoft Co.,Ltd 34

35. Action on class
 Teacher
– hauc2@yahoo.com
– 0984380003
– https://play.google.com/store/search?q=thsoft+co&c=apps
 Captions
 Members
VTC Academy THSoft Co.,Ltd 35