Two modules together Week 1: introduction Software Workshop 1 - - PDF document

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Week 1: introduction

• The Java programming language
• Lecturer: Dr. Mark Ryan
• Teaching assistant:
• Dr. Dimitar Guelev
• Demonstrators: Will, Kevin, Adam, Julie,

James, Samuel, Laurence, James, Simon, Andre, Daniel, Andrew, Paul, Chris, Kumutha, Peter, Daniel, Kerry, Asuka, . . .

School of Computer Science, University of Birmingham Java Lecture notes. M. D. Ryan. September 2001.

Two modules together

• Software Workshop 1 (20+20 credits)

– Taken by: CS, CSSE, CSSEBS

• Software Workshop 1A (10+10 credits)

– Taken by: AICS, half-CS, BioInf

• Both share two lectures and one exercise class per

week.

• The 20 credits have an extra lecture a week, and extra

exercise classes, and a different examination.

• Please make sure you know whether you are 10cr
• r 20cr.

Timetable information

• Lectures:

– Monday, 5pm. LT1, Law (20 cr only) – Thursday, 5pm. Vaughan Jeffreys, Education . – Friday, 1pm. LT1, Law

• One exercise class per week

– Monday, 1pm.

• Lab sessions on Tuesdays, Wednesdays, Fridays

– Suggestion: pick any two hours

• Weekly exercises (more for 20cr than 10cr)

– some assessed, some formative – see the WWW page for assessment details.

The WWW page for this module

www.cs.bham.ac.uk/courses/java/fyw/

• From the School home page:

– follow People, Lecturers and professors, Dr Mark D Ryan, Personal Homepage, Teaching, Software workshop, First Year Workshop home page.

• The WWW page gives you a week-by-week

account of the material, and the exercises.

Books recommended for this module

• Ira Pohl and Charlie McDowell, Java by

Dissection, Addisson Wesley, 2000. £25.

• Cay Horstman, Computing Concepts with Java 2,

John Wiley & Sons, 1999. £25.

• (Reference book) C. Horstmann and G. Cornell,

Core Java, 4th edition, Vol. 1,2, Prentice Hall, 1999.

• If you already have a different Java book, use it.

A very simple program

/* a program to print “Hello, World”

• n the screen */

public class Hello { public static void main(String[] args) { String greeting = "Hello, World!\n"; System.out.print(greeting); } }

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Points to note

• Every program has at least one “class”, and

the class declaration begins public class classname

• Every program has a class with a main

“method” in it, and that is declared with public static void main (String[] args)

The program is a piece of text

• You type it in, using an editor

– The editor you will use is called emacs – The emacs editor is very well-suited for typing programs, and will help you in various ways (syntax highlighting, indentation, bracket matching). – Other editors you have heard of include MS Word; this is not suitable for typing programs.

• When you finish typing and editing

(correcting) your program, you save it on disk.

– The file name should be Fred.java, where Fred is the class name in the program. – A disk in Unix is organised into directories, which are like folders in Windows 95/98/2000. – Your directory is /home/students/ug/ug12aaa/ – (the ug12aaa part is unique to you)

• You will create a subdirectory for the

exercises of the Workshop

– You might call it java-workshop – In which case its full name is /home/students/ug/ug12aaa/java-workshop – Potentially, another student could access the files in your directory, by doing cd /home/students/ug/ug12aaa/java-workshop – You can, and should, prevent this by read- protecting this directory with the command chmod go-rwx java-workshop

• When you have saved your file, you will

compile it using the command javac Fred.java

– First, you should change to the right directory, using

cd ~/java-workshop

– Compiling the program means transforming it into a form which the computer can execute. – If all goes well, the compiler will not produce any error messages, and will create the file Fred.class. – You can look at Fred.class in emacs if you want, but it will appear to be gibberish.

• Having compiled your program, you run it with

the command java Fred

– Note the difference between the compiling step,

javac Fred.java

and the running step,

java Fred

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• If there were mistakes in your program, the

compiler will complain about them, or they might show up when you run the program.

• Three kinds of errors:

– Compile-time errors (e.g. syntax errors) Errors that the compiler tells you about. – Run-time errors (e.g., division by 0) These are reported only when you try to run the program. – Programming errors (also called logical errors): it didn’t do what you intended.