Java the UML Way version Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1 Introduction Preliminaries for reading this book page 2 Familiarize yourself with the book and the web page!page 3 We can contemplate the computer as layeredpage 4 Two types of Java programspage 5 A small program (an application) page 6-7 From source code to runnable programpage 8-9 Running an appletpage 10

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 2 Preliminaries for Reading This Book You have used a computer for a while. You know –the use of Windows incl. Windows Explorer, cut and paste, etc. –the terms file, directory and sub-directory You know a little about the significance of a file’s extension, examples: –Windows program files have the extension exe. –Files with the extension doc are data files - input for the application Word. –Note the difference between program files and data files. You have some experience in the use of the Internet. Windows has a graphical user interface. MS-DOS-prompt is an example of a textual user interface, where we type commands to navigate the files. An advantage to know a few such commands. You know a little about the computer’s construction: –microprocessor –internal memory (RAM) and secondary memory

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 3 Familiarize Yourself with the Book and the Web Page! The web page: Every chapter has the following elements: –Introduction with learning-goals –The chapter text Most sections end with small problems. The most important ones are included in this series of slides, connected to the relevant text. Solutions to the problems are on the web page. All numbered example programs are on the web page, for downloading and running. –At the end of every chapter Review problems, covering the most important parts of the chapter. Programming problems. Solutions for many of these are on the web page. List with explanations of new concepts. And remember: It is not possible to become a good programmer by reading. You have to program a lot.

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 4 We Can Contemplate the Computer as ”Layered” Graphical windows system Command shell Kernel fopen, fclose C:\DOS> dir a small amount of commands (”calls)” working on the internals of the computer textual user interface, many available commands, each of them corresponding to several kernel commands The distinction between the layers isn’t clear on all systems. In some systems, however, the distinction is clear enough to easily switch windows systems.

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 5 Two Types of Java Programs Java applets –When you fetch a page on the web, the page is transferred from a server machine (where the page is stored) to a client machine (your computer). –You read the web page by means of a program called a browser (i.e. Netscape or Microsoft Explorer). –The page may refer to a (a bit special) type of program file stored on the server machine. –The program file is transferred to the client machine, and the browser runs the program. –Such a program is an applet, and is stored on a file with the extension class. Java applications –These are ”ordinary programs”, not only for the Internet. –Has the extension class, not exe. –Run by a program called java. –Not necessarily connected to the Internet at all.

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 6 A Small Program (an Application) We type in the program as plain text. We can’t add formatting such as italics or different fonts. Therefore we don’t use a word processor, but a text editor, when typing in programs. Notepad, WinEdit and TextPad are examples of text editors. TextPad:

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 7 The Program PrintText.java /* * PrintText.java VBH * Prints text several times * */ class PrintText { public static void main(String[] args) { System.out.println("Our first program..."); for (int i = 0 ; i<10 ; i++) System.out.println("About to learn Java!"); } class name comments file name same as class name, with extension java. print one line do next thing 10 times Our first program... About to learn java!About to learn java!About to learn java!About to learn java!About to learn java! printout when running the program

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 8 From Source Code to Runnable Program The program code we type in is called source code. It is a good habit to put the source code on a file with the same name as the class. Many tools enforce this. The file name must have the extension java. Here: PrintText.java. Mind the upper and lower case. Java programs must be translated into byte code. The byte code can be run on several types of computers. –Necessary when applets are downloaded from the Internet. The Java interpreter translates into the relevant machine code. Programs written in other programming languages are often translated directly into machine code (the language which the microprocessor uses). Source code, HelloWorld.java Byte code, HelloWorld.class. class HelloW... public static... ¤() CompilingRunning by an interpreter

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 9 How to Run the Program (Application) We need –A program which translates from source code to byte code: javac.exe –A program which takes the byte code and runs the program: java.exe - (The Java interpreter). In an MS-DOS window: –Assume that the file PrintText.java is in the directory c:\javaprograms. –Go to this directory: c:\windows>cd c:\javaprograms c:\javaprograms> javac PrintText.java c:\javaprograms> java PrintText The result is displayed in a window, and looks like this: In a tool/editor: –Many editors let you compile and run directly from where you type the program. Our first program... About to learn java!About to learn java!About to learn java!About to learn java!About to learn java!

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 10 Running an Applet An HTML file must contain a reference to the applet: – Let’s name the HTML file SimpleApplet.html. It can be run in more than one way: –With the program appletviewer: From the MS-DOS prompt: >appletviewer SimpleApplet.html From a tool: You have the applet’s source code in a window. You press for compiling and running of it. Often, a tiny HTML file is created on the fly, and this is passed to appletviewer. appletviewer only shows the applet, not the other parts of the web page (HTML file). –The file can be opened in a web browser: file:///J|/USER/JavaBook/ExCh4/SimpleApplet.html –The file can be retrieved from a web server:

Only to be used in connection with the book "Java the UML Way", by Else Lervik and Vegard B. Havdal. ISBN , John Wiley & Sons Ltd 2002 The Research Foundation TISIP, Chapter 1, page 11 Before continuing you have to familiarize yourselves with the tools you are going to create your Java programs with. Do the downloading and installation, if not already done. See Appendix A. Make the program on page 10 work, so that the printout becomes like the one on page 11. If you use the SDK from Sun, try to use the procedure on pages Find the book’s web page, and find your way around. Download the solutions for the small problems.