Intro to advanced programming (lập TRÌNH NÂNG CAO SLIDE)

ABOUT THE JAVA TECHNOLOGY Java technology is both a programming language and a... ABOUT THE JAVA TECHNOLOGY In the Java programming language, all source code is first written in plain

ADVANCED PROGRAMMING (LTNC)

Course Topics – Java Basics

 Declarations and Access Control

Course Topics – Java Basics

 Constructor and instantiation

 Class and Object varialables

Course Topics – GUI (SWING)

 Performing custom painting

 More Swing Features and Concepts

 How to use the Swing components

 Attendance: 15%

 Midterm exam: 35% (Lab)

 Final exam: 50% (Lab)

Bibliography

1 Core JAVA, Volume I , Cay S Horstmann, Gary

Cornell, Sun MicroSystem Press, USA 2008.

2 Core JAVA, Volume II , Cay S Horstmann, Gary

Cornell, Sun MicroSystem Press, USA 2008

Computer Program

Set of instructions written in

a programming language that tells the computer what to do

The Programming Process

Defining the problem

Planning the solution

Coding the program

Testing the program

Documenting the program

The Programming Process:

Defining the Problem

 What is the input

 What output do you expect

 How do you get from the input to the output

Coding the Program

 Translate algorithm into a formal programming

Computer Programming Languages

1 Machine code or machine languages

 A sequence of 0’s and 1’s giving machine specific

instructions Example: 00011001

 Displayed as hexadecimal

 Only language the computer understands

 All other programming languages are translated to machine language

 Computer dependent

Computer Programming Languages

 Assembler: Assembly code  machine code

 Disassembler: machine code  assembly code

Computer Programming Languages

3 High-level languages

 Similar to everyday English and use mathematical

notations (processed by compilers or interpreters)

 Example of a C statement: a = a + 8;

High-level Languages and Their Inventors

 FORTRAN John W Backus, 1954

 BASIC George Kemeny and Tom Kurtz, 1964

 Pascal Nicolas Wirth

 C Dennis M Ritchie

 C++ Bjarne Stroustrup

 Java James Gosling

 C# Anders Hejlsberg

Programming Language Popularity

Language Level

ABOUT THE JAVA TECHNOLOGY

 Java technology is both a programming language and a

ABOUT THE JAVA TECHNOLOGY

 In the Java programming language, all source code is first written in plain text files ending with the .java extension Those source files are then compiled into .class files by the Java compiler (javac) A .class file does not contain code that is native to your processor; it instead contains

bytecodes the machine language of the Java Virtual

Machine The Java launcher tool (java) then runs your

application with an instance of the Java Virtual Machine

ABOUT THE JAVA TECHNOLOGY

JVM – Java Virtual Machines

 Virtual machines depend on specific platforms

(hardware, OS)

 Provide Java programs with (platform independent) run-time environments

 Ensure system security

 Normally provided as software

 JRE - Java Runtime Environment

 Java platform: JVM + APIs

The Java Runtime Environment

 The Java application environment performs as

follows:

JVM™ Tasks

– Loads code – Performed by the class loader

• Loads all classes necessary for the execution of a program.

• Avoids execution of the program whose bytecode has been changed illegally.

– Verifies code – Performed by the bytecode verifier

• The code adheres to the JVM specification.

• The code does not violate system integrity.

• The code causes no operand stack overflows or underflows.

• The parameter types for all operational code are correct.

• No illegal data conversions have occurred.

– Executes code – Performed by the runtime interpreter

Java Technology Runtime Environment

JDK – Java Development Kit

Sun Microsystems (http://java.sun.com)

– javac compiler, converts source code into Java bytecode

– java interpreter and application loader

– appletviewer interpreter, run and debug Java applets

without a web browser

– javadoc documentation generator, automatically

generates documentation from source code comments

– jdb debugger

– javap class file disassembler

Types of Java applications

 Desktop application – Java SE (Java Standard Edition)

– Java Application: normal Java application running on

desktops; console or GUI

– Java Applet: embedded application running within Web browsers

 Server application – Java EE (Java Enterprise Edition)

– JSP và Servlet, JSF, EJB

 Mobile (embedded) application – Java ME (Java Micro Edition)

 Java Card

Java Desktop Applications

 Complete application programs

 Console or GUI

 Launched by java command

A Sample Java program

// This is a simple program

public class TestGreeting {

public static void main(String[] args) {

System.out.println("Hello, world" );

}

}

TestGreeting.java

commented line

Declare new class

main method from where the program begins its execution

displays the string Hello, world on

same name with class

Compiling & executing the program

 To actually run the program, a java interpreter called

java is required to execute the code

 The java compiler creates a file called

TestGreeting.class that contains the byte codes

Passing Command Line Arguments

class CommLineArg {

public static void main (String[] pargs) {

System.out.println( "These are the arguments

passed to the main method." );

Small improvement

 Two classes in separated files

public class TestGreeting {

public static void main(String[] args) {

Greeting gr = new Greeting();

gr.greet();

} }

TestGreeting.java

public class Greeting {

public void greet() {

System.out.print( "Hello, world" );

} }

Greeting.java

Compile and run

Java Applets

 Embedded into webpages, i.e run in web browsers.

 Or in appletviewer

 Limited graphical interface

 No access to client’s resources

 can do no evil

A simple applet

// Java packages

import java.awt.Graphics;

import java.applet.Applet;

public class Welcome extends Applet {

public void paint(Graphics g) {

// call superclass version of method paint

Embedded into a Webpage

• in web browser

• In applet viewer: appletviewer Welcome.html

Integrated Development Environment - IDE

 Provides comprehensive facilities to computer

programmers for software development

 Normally consists of a source code editor, build

automation tools and a debugger.

 IDEs can contain compiler, interpreter.

 Some Java IDEs:

 Eclipse

 Netbean

MORE ABOUT THE JAVA TECHNOLOGY

 The Java Platform

 A platform is the hardware or software environment

in which a program runs We've already mentioned

some of the most popular platforms like Microsoft

Windows, Linux, Solaris OS, and MacOS Most

platforms can be described as a combination of the

operating system and underlying hardware The Java platform differs from most other platforms in that it's a software-only platform that runs on top of other

hardware-based platforms The Java platform has two components:

 The Java Virtual Machine

The Java Application Programming Interface (API)

MORE ABOUT THE JAVA TECHNOLOGY

 Simple

programmed easily without a lot of esoteric training and which leveraged today's standard practice.Java omits

many rarely used, poorly understood, confusing

features of C++ that, in our experience, bring more

grief than benefit.

 The syntax for Java is, indeed, a cleaned-up version of the syntax for C++ There is no need for header files, pointer arithmetic (or even a pointer syntax),

structures, unions, operator overloading, virtual base

classes, and so on.

MORE ABOUT THE JAVA TECHNOLOGY

 The object-oriented features of Java are

comparable to C++ The major difference between Java and C++ lies in multiple inheritance, for which Java has found a better solution, and in the Java

metaclass model

MORE ABOUT THE JAVA TECHNOLOGY

 Distributed

 Java has an extensive library of routines for coping with TCP/IP protocols like HTTP and FTP Java applications can open and access objects across the Net via URLs with the same ease as when accessing a local file

system.

 The networking capabilities of Java to be both strong and easy to use Anyone who has tried to do Internet programming using another language will revel in how simple Java makes onerous tasks like opening a socket connection

MORE ABOUT THE JAVA TECHNOLOGY

 Robust

 Java is intended for writing programs that must be reliable in a variety of ways Java puts a lot of emphasis on early checking for possible problems, later dynamic (run-time) checking, and eliminating situations that are error-prone The single

biggest difference between Java and C/C++ is that Java has a pointer model that eliminates the possibility of overwriting

memory and corrupting data

 This feature is also very useful The Java compiler detects

many problems that, in other languages, would show up only

at run time As for the second point, anyone who has spent

hours chasing memory corruption caused by a pointer bug will

be very happy with this feature of Java

MORE ABOUT THE JAVA TECHNOLOGY

instructions which have nothing to do with a particular

computer architecture Rather, they are designed to be both easy to interpret on any machine and easily translated into native machine code on the fly

 Portable

 Unlike C and C++, there are no

"implementation-dependent" aspects of the specification The sizes of the

primitive data types are specified, as is the behavior of

arithmetic on them

MORE ABOUT THE JAVA TECHNOLOGY

 Interpreted

directly on any machine to which the interpreter has

been ported Since linking is a more incremental and

lightweight process, the development process can be

much more rapid and exploratory.

 High Performance

 While the performance of interpreted bytecodes is

usually more than adequate, there are situations where higher performance is required The bytecodes can be translated on the fly (at run time) into machine code for the particular CPU the application is running on.

MORE ABOUT THE JAVA TECHNOLOGY

 Secure

 Java is intended to be used in networked/distributed environments Toward that end, a lot of emphasis has been placed on security Java enables the construction

of virus-free, tamper-free systems.

A SHORT HISTORY OF JAVA

 Java goes back to 1991, when a group of Sun engineers, led

by Patrick Naughton, Sun Fellow and James Gosling, wanted to

design a small computer language that could be used for consumer devices like cable TV switchboxes Since

these devices do not have a lot of power or memory, the

language had to be small and generate very tight code Also, because different manufacturers may choose different central processing units (CPUs), it was important not to be tied down

to any single architecture The project got the code name

A SHORT HISTORY OF JAVA

 The Green project (with a new name of "First Person, Inc.") spent all of 1993 and half of 1994 looking for people to buy its technology—no one was found

 The World Wide Web part of the Internet was growing bigger and bigger The key to the Web is the browser that translates the hypertext page to the screen In 1994, most people were using Mosaic, a noncommercial Web browser that came out of the supercomputing center at the University of Illinois in 1993

 In the SunWorld interview, Gosling says that in mid-1994, the language developers realized that "We could build a real cool browser It was one of the few things in the client/server

mainstream that needed some of the weird things we'd done: architecture neutral, real-time, reliable, secure—issues that

weren't terribly important in the workstation world So we built

a browser."

A SHORT HISTORY OF JAVA

 Sun released the first version of Java in early 1996

People quickly realized that Java 1.0 was not going to cut it for serious application development

 The big news of the 1998 JavaOne conference was the

upcoming release of Java 1.2, which replaced the early toy-like GUI and graphics toolkits with sophisticated and scalable

versions that come a lot closer to the promise of "Write Once,

Run Anywhere"™ than their predecessors Three days after

(!) its release in December 1998, Sun's marketing department changed the name to the catchy term Java 2 Standard Edition Software Development Kit Version 1.2

 Besides the "Standard Edition," two other editions were

introduced: the "Micro Edition" for embedded devices such as

HOW WIL JAVA TECHNOLOGY CHANGE MY LIFE

 Get started quickly: Although the Java programming

language is a powerful object-oriented language, it's easy to

learn, especially for programmers already familiar with C or C++

 Write less code: Comparisons of program metrics (class

counts, method counts, and so on) suggest that a program

written in the Java programming language can be four times smaller than the same program in C++

 Write better code: The Java programming language

encourages good coding practices, and its garbage collection helps you avoid memory leaks Its object orientation, its

JavaBeans component architecture, and its wide-ranging, easily extendible API let you reuse other people's tested code and

introduce fewer bugs

HOW WIL JAVA TECHNOLOGY CHANGE MY LIFE

 Develop programs more quickly: Your development time

may be as much as twice as fast versus writing the same

program in C++ Why? You write fewer lines of code and it is a simpler programming language than C++

 Avoid platform dependencies: You can keep your program

portable by avoiding the use of libraries written in other

languages

 Write once, run anywhere: Because Java applications are

compiled into machine-independent bytecodes, they run

consistently on any Java platform

 Distribute software more easily: With Java Web Start

technology, users will be able to launch your applications with

a single click of the mouse

CREATING YOUR FIRST APPLICATION

 Create a source file A source file contains text,

written in the Java programming language, that you and other programmers can understand You can use any text editor to create and edit source files

 Compile the source file into a class file The Java

compiler , javac, takes your source file and translates its text into instructions that the Java Virtual Machine

can understand The instructions contained within this file are known as bytecodes

 Run the program The Java launcher (java) uses the

Java Virtual Machine to run your application