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G51PR1
Introduction to Programming I
2000-2001
University of Nottingham
Unit 1 : Introduction
Overview
 Background
– Teaching Staff
– Course Details
– Assessment
 PR1 Summary
 Resources
 Programming
– Programming Languages
– High Level Languages
– Interpreters / Compilers
 Introduction to Java
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Java History
Java Properties
Types of Programs
JDK tools
The HelloWorld program
 Using CourseMaster
Teaching Staff
 Lecturer : Tsintsifas Athanasios (thanassis)
– [email protected] Room:C73 (mon 10-12) (wed 9-10) (fr 10-12)
 CourseMaster Administrator : Pavlos Symeonidis
– [email protected] Room:C73 (tues 2-6) (thur 2-6)
 Help Desk: Tarek Hegazy,
– [email protected] Room : C75
 Lab Assistants (terminal room - lab hours).
 CourseMaster help (via email), [email protected]
Course Details
 20ish lectures plus lab sessions.
 One to three coursework exercises per week.
 You will be assigned to 1 of 4 lab sessions
– 2-4 & 4-6 Tuesday
– 2-4 &, 4-6 Thursday
 Prerequisites : None (but you must do CUA concurrently).
 Objectives : To learn to think algorithmically and to express in
sound implementations.
Assessment
 100% coursework via the CourseMaster system (used to be
called Ceilidh, check www.cs.nott.ac.uk/~ceilidh).
Assessment
Starting on Friday 13th of October
Exercises close 10 days after opening (every Monday 12:00)
Usually you have three attempts to submit.
The last attempt is always the final.
Feedback after each submission gives you enough information to
infer the correct the solution.
 More on the process of using CourseMaster on Friday.
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Summary of PR1
 9-10 units of 1-2 lectures
Resources
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Sun file servers (jdk is installed in solaris)
PCs (jdk is installed in all lab PCs)
CourseMaster installed in all lab PCs
PFE editor or Emacs-JDE
JDK 1.3
Course Transparencies : http://www.cs.nott.ac.uk/~azt/pr1
Reading
Recommended:
 Java Gently by Judy Bishop (Addison-Wes).
 Java. How to Program by Deitel & Deitel (Prentice Hall).
 Developing Java Software by Winder & Roberts (Wiley).
 Java in a Nutshell by Flanagan (O’Reilly).
 Thinking in Java (Bruce Eckel) (available on the web)
Other Sources of Information:
 CourseMaster : http://www.cs.nott.ac.uk/CourseMaster
 Sun Java Tutorial :
– http://java.sun.com/docs/books/tutorial/getStarted/index.html
 WWW – general : search in www.google.com!
 Intense Java Course : http://www.cs.nott.ac.uk/~azt/java.htm
Programming
 "A program is a sequence of instructions. A recipe, a musical score,
and a knitting pattern are all programs."
P Grogono, Programming in Pascal.
- The way to deal with an impossible task is to chop it down into a
number of merely very difficult tasks, and break each one of them
into a group of horribly hard tasks, and each one of them into tricky
jobs, and each one of them...
(Terry Pratchet, Truckers)
Programming Languages
 There are four basic programming language levels:
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machine language
assembly language
high-level language
fourth-generation language
 Each CPU has its own specific machine language
 The other levels were created to make programming easier
Programming Languages
 A program must be translated into machine language before it
can be executed on a particular type of CPU
 This can be accomplished in several ways
 A compiler is a software tool which translates source code into a
specific target language
 Often, that target language is the machine language for a
particular CPU type
 The Java approach is somewhat different
High Level Languages
Old-fashioned languages include:
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BASIC - often used by beginners on home computers.
FORTRAN - old but still popular with some scientists and
engineers, new versions are introduced every few years.
Algol - an elegant little-used internationally designed language,
whose features are being incorporated into other languages.
COBOL - a widely used and well standardised language used in
commerce.
APL - an interactive scientific language with a very
mathematical notation.
PL/I - a failed attempt by IBM at achieving an all-purpose
language, now almost dead.
High Level Languages
Other Languages :
 Pascal - good for beginners, often taught as a first language.
 Modula2 - a development of Pascal to make it more realistic for large
programs, and to enable modern program design techniques to be
used.
 C - a practical language, see below.
 C++ - an object-oriented development of C.
 ADA - a USA Department of Defense standard, now adopted by the
UK Ministry of Defense also, aimed at safe programming for real-time
embedded systems.
 Java – A robust, secure, portable, network enabled variation on
C/C++.
High Level Languages
Compare the COBOL:
rate_per_hour multiplied by hours_worked gives gross_pay
with C/C++:
pay = rate * hours
Some language aims:
understanding, documentation –> commercial (eg COBOL).
handling vectors or complex numbers –> scientific/engineering (FORTRAN).
simplicity –> beginners (Basic, Pascal).
safety –> real time systems (ADA, Modula-2).
complexity –> object-oriented (C++, Eiffel, Java).
Interpreters vs Compilers
Interpretation :
 BASIC & APL are interpreted.
 Each line is decoded and interpreted by the computer as it is executed.
 Instructions in loops may have to be interpreted many times.
 This is inefficient and causes the computer to run slowly.
Compilation :
 Most other languages are compiled.
 Whole program first analysed by a compiler (another program).
 Converted into a machine executable form.
 Runs much faster (an order of magnitude or more).
 Can apply many types of optimisation during or after compilation.
 In two parts – compilation into an object module, then loading/linking into the
executable.
Java: What is it?
Sun’s Description….
Java is a :
 Simple
 Object Oriented
 Distributed
 Interpreted
 Robust
 Secure
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•
•
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Architecture Neutral
Portable
High Performance
Multithreaded and
Dynamic
programming language.
It contains an extensive library of classes for graphics
programming, input/output, string handling, maths functions,
basic data structures, etc.
Java History
 C language was evolved as a portable operating system language
 Dennis Ritchie (at Bell labs) developed it from B (which came from
BCPL).
 Originally ran on a DEC PDP-11 computer in 1972.
 C++ is an object-oriented extension to C developed by Bjarne
Stroustroup early 80’s.
 Sun had an internal corporate research project, Green, in 1991, to
develop intelligent consumer devices.
 Project lead to the language Oak (James Gosling) based on
C/C++.
 Oak about to be cancelled when WWW came along.
 Sun saw renamed Oak to Java and saw potential for use on the
web
 Java formally announced in May ’95.
 Since then, Java generated huge interest.
Java’s Versions
 Java was officially announced in May 1995
Java 1.2.2
Java 1.1
First Idea
Java 1.3
Java 1.2
Java 1.02
91
92
Green Project
93
94
95
OAK
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97
98
99
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Simple
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Has a small set of Language Constructs.
Borrows the C and C++ syntax.
Is free from pointers.
Uses Garbage Collection.
Does not use header files and preprocessors.
Object Oriented
 Not hybrid like C++.
 Supports the basic notions of OO :
– Abstraction,
– Modularity,
– Encapsulation,
– Hierarchy,
– Typing,
– Concurrency,
– Persistance.
Distributed
 Works on a variety of platforms.
 Provides support for :
• Networking,
• Internet,
• Remote Objects.
Interpreted
 The Java compiler translates Java source code into a special
representation called bytecode
 Java bytecode is not the machine language for any traditional CPU
 Another software tool, called an interpreter, translates bytecode into
machine language and executes it
 Therefore the Java compiler is not tied to any particular machine
 Java is considered to be architecture-neutral
Java
Source
File
Java
Compiler
Java
Java
Bytecode
Java
Bytecode
File
Bytecode
File
File
JVM
Robust
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Exception and Error handling.
Multi-Tasking.
Memory protection and management.
Allows Modular development.
Extensive compile-time checking.
Secure
 The features of bytecode and its interpretation, prevent
unintentional or intentional sabotage of compiled programs.
 Security has been considered in many levels.
Architecture Neutral
 Bytecode can run on any JVM on any platform.
 “Write Once run Anywhere”.
 JDK implementation on many platforms.
Java Bytecode
Mac
VM
Win95
VM
Solaris
VM
MacOS
Win95
Solaris
Java
HW
Portable
 The bytecode can run on virtual machines (VM) above different
operating systems :
• MacOS
• Windows95/NT/CE
• Solaris
• OS2
• etc
 It can also run directly on hardware.
High - Performance
 Multithreading allows more than one task in a program.
 With JIT compilers the interpreted code compiles at run time and
gives almost native code speed.
Java Bytecode
Native
JIT
Java
VM
Operating System
Hardware
Java
OS
Java
HW
Dynamic
 Java has been built to support the development of
dynamically extendable systems.
 Java provides dynamic linking of the binary code at
runtime.
Java’s Genealogy
Java : Types of Programs
 Applets :
• Execute on HTML Browsers.
• Have severe security restrictions.
 GUI Applications :
• Are Interpreted and Executed.
• Use the current’s platform’s GUI widgets.
• Mostly use Java’s AWT or JFC packages.
 Console Applications :
• Simple Text Console.
JDK basic tools
 javac (Compiler)
.java->.class
• The Java Language Compiler that you use to compile
programs written in Java into bytecodes.
Example : java HelloWorld.java
 java (Interpreter)
executes .class
• The Interpreter that you use to run programs written in Java.
Example : javac HelloWorld
 javadoc (Doc. generator)
.java html
• Generates documentation in HTML format from Java source
code.
Example : javadoc HelloWorld.java
The First Java Program
Filename: HelloWorld.java
public class HelloWorld {
public static void main(String argv[] ) {
System.out.println("Hello World!!!");
}
}
CourseMaster
 CourseMaster is a “Courseware” system that provides for :
– The presentation of Information
• summaries, notes, coursework questions, hints, daily messages
– The administration of coursework
• coursework delivery,
• submission management,
• overall class management
– The automatic assessment of coursework
• solution space modeling,
• assessment and feedback mechanisms,
• plagiarism checking tools
Logging in CM client:
 To login to CM you need both a windows and a unix password.
 Once you are in windows you can click the “CM” icon
 This will get you to the login screen :
Unix Password!
Message of the day :
 Informs you about the latest in exercises
 Do read it!
CourseMaster Course Level :
 Options
 Exit
 MOTD
 Notes
 Summary
CourseMaster Unit Level
 Notes
 Summary
CourseMaster Exercise Level :
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Setup
Develop
Submit
Question
View TD
Marks
Run
Run TD
Setup :
 Puts the
skeleton
source and
other files
in your
working
area
 Do not
setup over
your
solution
Develop :
 PFE is CM’s
standard editor
for Java
source
 You can
always change
it later on!
Compile :
 From Menu :
Execute->javac
After Compilation :
Good News
Bad News
Ctrl + G
Gets you to
any line number
Run a program
Two options :
 1. From PFE, Execute->java
– PFE : Options->Preferences->Execute Menu->java->Edit :
– Start command (as independent process OR capture output)
 2. From CourseMaster, Exercise Level->Run
Submit
 After having developed the solution you need to refresh the CM
browser by refreshing the course tree structure.
 You will be asked to confirm and then wait for the result.
Expanded
Result tree
Submission Number
Feedback for
every check
Other Options :
 View TD : Allows you to see the testing
input that CM uses for the particular exercise.
 Marks : Allows you to check the exercise’s
last submission
 Options : Allows you to change :
– Visual properties.
– Editor command.
Summary
 Background
– Teaching Staff
– Course Details
– Assessment
 PR1 Summary
 Resources
 Programming
– Programming Languages
– High Level Languages
– Interpreters / Compilers
 Introduction to Java
–
–
–
–
–
Java History
Java Properties
Types of Programs
JDK tools
The HelloWorld program
 Using CourseMaster