Programming Our First Java Program Yingcai Xiao. What to Do Set up for Java Programming Write our first Java Program with IDE Write our first Java Program

ProgrammingOur First Java Program

Yingcai Xiao

What to Do

Set up for Java Programming

Write our first Java Program with IDE

Write our first Java Program without IDE

Review

Programming a Computer

Computer

Computer: a device for data processing.

von Neumann architecture is used by all digital computers. • It runs stored programs. • It has the following basic components:

Memory, IO, CPU, Secondary Storage.

Computer Programs are stored instructions for data processing. They are composed of

Programming is to define Data Structures to store data and Algorithms to process data.

Types of Programming Languages

Machine Languages: binary opcodes, hardware dependent. Hard to program and not portable. Programs are called binary code and are understandable by the targeted hardware.

Assembly Languages: English-like instructions, platform/OS dependent. Easier to program but not portable. Programs are called assembly code and need to be translated into binary code.

High-level Languages: English-like instructions, platform/OS independent. Easy to program and portable. Programs are called source code and need to be translated into binary code.

Special Programs

• Operating System: a program that manages a computer (its memory, CUP, SS, IO (networking)).

• Compiler: a program that translates source code written in a high-level programming language into binary code.

• Loader: a program load an executable into memory for execution.

• Linker: a program that links all related binary codes (libraries) together to make an executable.

• Editor: a program that can be used to write source code.

IDE (Integrated Development Environment)

• Contains an editor, a compiler, a linker/loader, a debugger, sometimes, a profiler, a source code version controller, and other tools.

• A complete environment for developing software.

• Always provides library programs for performing common tasks.

Setting Up Your Computer for Java Program Development

• The lab computers are set for Java program development.

• Follow the instructions in “Before You Begin” in the textbook to set up your own computer.

• You can also follow the instructions at

Creation of a C++ program

Source File (.cpp)

Intermediate File (.I)

Object File (.obj)

Binary File (.exe)

Preprocess

Compile

Link

Edit

Load

Creation of a Java program

Source File (.java)

Binary Byte File (.class)

Native Binary Code

Preprocess/Compile

JRE/JVM: load/valid/translate/execute

Edit



Creation of a Java Program

• Creation Source code : use a text editor (Notepad) to write the source code. Java source code (.java) is portable to all platforms as long as there is a java compiler. notepad ics.java

• Compile the source code: Java source code are converted into Java bytecode (.class) by the Java compiler (javac.exe). Java byte code are portable to all platforms as long as there is a Java runtime environment. javac ics.java

• Run the bytecode: Java bytecode (.class) are executed by the Java virtual machine. java ics

Common Binary Code?(Binary Code Reuse Cross OS)

Traditional Compilation

Source Code for Language 1

Language 1 Compiler on OS1

Binary Code for OS1

OS1



Binary Code for OS2

OS2

OS-Independent Code: Intermediate Languages

The trend to support machine-independent binary code is to compile the source code into the binary format of an intermediate language.

And to provide an interpreter for the intermediate language on each OS to translate the binary code of the intermediate language into the native binary code of the OS.

OS-Independent Compilation: Intermediate Language



Intermediate Binary Code for Language1

OS1

Intermediate Code Interpreter OS1

OS2


Binary Code for OS2Binary Code for OS1

Intermediate Code Interpreter OS2

Java Intermediate Language: Java Bytecode

Java Source Code (.java)

Java Compiler (javac) on OS1

Java Bytecode (.class)

OS1

Java Interpreter on OS1 (java)

OS2



Java Interpreter on OS2 (java)

Program statements are interpreted one at a time during the run-time.

JIT Compiler

An interpreter interprets intermediate code one line at a time. Slow execution.

A JIT (Just-In-Time) compiler compiles the complete code all at once just into native binary code before execution. Faster execution.

JIT Complier: Java Bite Code Compiler

Java Source Code (.java)


Java Bytecode (.class)

OS1

Java JIT Compiler on OS1

OS2



Java JIT Compiler on OS2

All programming statements are compiled at compile time.

.NET OS-Platform-Independence

MSIL: Microsoft Intermediate Language (Used by .NET)



MSIL Code

OS1

MSIL JIT Compiler on OS1

OS2



MSIL JIT Compiler on OS2

JIT Compilation in .NET

All MSIL code are JIT-compiled to native binary code before execution. No run-time interpretation, faster execution.

A Common Language?(Source Code Reuse Cross Languages)

.NET CTS/CLR

.NET Common Language Runtime

To make .NET language independent, CLR (Common Language Runtime) is defined as the runtime environment.

CLR defines CTS (Common Type System) which should be followed by all languages to be used in the .NET framework.

The code that follows CTS standard and runs through CLR is called managed code.

.NET Language-Independence

CLR: Common Language Runtime



MSIL Code Confirming CTS (Managed Code)

OS1

CLR on OS1

OS2



CLR on OS2


.NET Architecture for Language and Platform Independence(fan-in and fan-out on MSIL)



OS1

CLR for OS1

OS2



CLR for OS2


MSIL Code Confirming CTS (Managed Code)

CLI (Common Language Infrastructure)

CLR/CTS for Everyone?

CLI : Common Language Infrastructure

A specification defines an environment for multiple high-level languages to be used on different computer platforms.

Created by Microsoft based on .NET, standardized by MS, Intel, HP and others, ratified by ECMA and ISO.

.NET is an implementation of CLI for desktop systems.

.NET Compact Framework is an implementation of CLI for portable devices.

Open Source implementations: Mono development platform (Novell), Portable .NET (dotGNU)

CLI (Common Language Infrastructure) SpecificationOpen Architecture for Language and Platform Independent Programming



OS1

CLR for OS1

OS2



CLR for OS2


CIL (Common Intermediate Language) Code

Confirming CTS (Common Type System)

A Common Language for the Internet?

A Common Language for the Internet

ASCII text (ISO/IEC 8859-1) is platform-independent.

=> HTTP (Hyper Text Transport Protocol)

=> Recognizable by all types of computers. (World Wide Web)

=> Everything is presented as text including data and programs.

Tim Berners-Lee

=> HTML (Hyper Text Markup Language)

A Common Language for the Internet

XML (eXtensible Markup Language), can be used to define data and programs over the Internet.

=> SOAP (Simple Object Access Protocol), XML-based

=> WSDL (Web Service Description Language), XML-based

Web Services

Libraries shared over the Internet at run-time.

Service interfaces specify what the services can do (contracts).

Service interfaces are defined in WSDL (Web Service Description Language)

UDDI Registry: Universal Description, Discovery, and Integration. (yellow page)

Access Standard:

SOAP: Simple Object Access Protocol

What did you learn?

Computer, programming, data structure, algorithm, programming languages, …

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Programming Our First Java Program Yingcai Xiao. What to Do Set up for Java Programming Write our first Java Program with IDE Write our first Java Program