Lecture 2: An Introduction to J# and.NET. 2 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-2 Objectives “Microsoft.NET is based on the.NET.

Lecture 2:

An Introduction to J# and .NET

2MicrosoftIntroducing CS using .NETJ# in Visual Studio .NET 2-2

Objectives

“Microsoft .NET is based on the .NET Framework, which consists of two major components: a run-time execution engine and an extensive software library. The Framework supports a wide range of programming languages, including J# which brings Java to .NET... ”

• Modern program execution• J#• Visual Studio .NET


HardwareHardware

Program execution in the 21st century

• Idea:– modern software executes using a run-time environment– why? portable and safe execution…

Operating SystemOperating System

Run-time EnvironmentRun-time Environment

Your ApplicationYour Application


Program execution in .NET

• Based on Common Language Runtime (CLR) + .NET Framework Class Library (FxCL)

• run-time environment + large software library

HardwareHardware


Common Language Runtime (CLR)Common Language Runtime (CLR)

Your ApplicationYour Application .NET Framework.NET FrameworkClass Library (FxCL)Class Library (FxCL)


So what is .NET?

• A technology for developing & executing software…– platform independent (XP, Pocket PC, Linux (Mono), BSD )– language independent

(28 languages listed at http://www.gotdotnet.com/team/lang//)

HardwareHardware


Common Language Runtime (CLR)Common Language Runtime (CLR)

Your ApplicationYour Application .NET Framework.NET FrameworkClass Library (FxCL)Class Library (FxCL)

J#J# C#C# C++C++ VBVB ……


What exactly is J#?

• "J-Sharp" is Java on the .NET platform– J# allows you to program using the Java language yet take

advantage of the Microsoft .NET platform

• What is Java?

– Java language syntax + Java class library• What is J#?

– Java language syntax (Java 1.4) + Java class library + .NET class library

– current Java language (i.e. v1.5, a.k.a. Java 5)

– partial support for Java class library (most of v1.1, some of v1.2)

– Additional library for Swing


Example in J#

• The infamous "hello world!" program– written in pure Java…

public class HelloApp{ public static void main(String[] args) { System.out.println("Hello world!"); }}

public class HelloApp{ public static void main(String[] args) { System.out.println("Hello world!"); }}


How to edit, compile, run?

• Visual Studio .NET• Visual Studio is Microsoft's IDE

– "Integrated Development Environment"

• One environment for all .NET programming:– editing– compiling– running– debugging


Step 1. Select new project…


Step 2. Create project…

• Select application language, then template


Step 3. Implement…

• Code the program in coding window– use "Solution Explorer" window for navigating program files

codingwindow

solutionexplorer


Step 4. Run!

• Just press F5 and off we go!– or use Debug menu, Start…– or click VCR-like "Play" button on the toolbar…

• Go ahead and try it — what happens?


The "console" flash

• By default, Visual Studio does the following:– opens console window– runs program– closes window

– so all you see is a flash!


Solution

• Keep console window open until user is done…

package HelloApp;

public class HelloApp{ public static void main(String[] args) throws Exception { System.out.println("Hello world!");

// keep console window open... System.out.println(); System.out.print("Press ENTER to exit..."); System.in.read(); }//main}//class

package HelloApp;

public class HelloApp{ public static void main(String[] args) throws Exception { System.out.println("Hello world!");

// keep console window open... System.out.println(); System.out.print("Press ENTER to exit..."); System.in.read(); }//main}//class


Very helpful IDE features…

• IntelliSense• Overloading• Tight integration of editor & compiler

– to name just a few…


IntelliSense!

• IntelliSense is a fantastic advance– context-sensitive programming aid– reduces programming errors– encourages experimentation and exploration

// keep console window open… System.o // keep console window open… System.o


Overloading

• J# allows multiple methods with the same name– We know this as overloading

– methods must differ in their parameter lists– VS depicts as a scrollable list…

// keep console window open… System.out.println( // keep console window open… System.out.println(


Editor & compiler integration

• Errors are highlighted in the code like spelling mistakes:


Working with Visual Studio

• Modes of programming:– "design": coding– "run": program is actively running– "break": program is paused (more on this later)

• How to know which mode you're in?


Visual Studio files

• Visual Studio produces lots of files

– bin folder contains .EXE, program input files– obj folder contains temporary files

– solution (.sln) is main file for working with VS

– project (.vjsproj) tracks source files, settings

– Visual J# (.jsl) denotes source code files


Re-opening a project

• To re-open a project and continue working…– double-click on the SOLUTION (.sln) file

or– startup Visual Studio and open .sln file


Summary

• Modern program execution:– based on virtual machines and large class libraries– in Java, known as JVM and JCL– in .NET, known as CLR and FxCL

• J# is Java on the .NET platform• VS is a modern, sophisticated, powerful IDE

Lecture 2: An Introduction to J# and.NET. 2 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-2 Objectives “Microsoft.NET is based on the.NET.

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