1. Lecture 2: An Introduction to J# and.NET

2. 2 MicrosoftIntroducing 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

3. 3 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-3 Hardware Program execution in the 21 st century Idea: –modern software executes using a run-time environment –why? portable and safe execution… Operating System Run-time Environment Your Application

4. 4 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-4 Program execution in.NET Based on Common Language Runtime (CLR) +.NET Framework Class Library (FxCL) run-time environment + large software library Hardware Operating System Common Language Runtime (CLR) Your Application.NET Framework Class Library (FxCL)

5. 5 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-5 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//)http://www.gotdotnet.com/team/lang// Hardware Operating System Common Language Runtime (CLR) Your Application.NET Framework Class Library (FxCL) J#C#C++VB…

6. 6 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-6 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

7. 7 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-7 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!"); }

8. 8 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-8 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

9. 9 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-9 Step 1. Select new project…

10. 10 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-10 Step 2. Create project… Select application language, then template

11. 11 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-11 Step 3. Implement… Code the program in coding window –use "Solution Explorer" window for navigating program files coding window solution explorer

12. 12 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-12 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?

13. 13 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-13 The "console" flash By default, Visual Studio does the following: –opens console window –runs program –closes window –so all you see is a flash!

14. 14 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-14 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

15. 15 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-15 Very helpful IDE features… IntelliSense Overloading Tight integration of editor & compiler –to name just a few…

16. 16 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-16 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

17. 17 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-17 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(

18. 18 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-18 Editor & compiler integration Errors are highlighted in the code like spelling mistakes:

19. 19 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-19 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?

20. 20 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-20 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

21. 21 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-21 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

22. 22 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 2-22 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