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01 Introduction
CE00858-1: Fundamental Programming Techniques
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Objectives
In this session, we will:• review the structure of the module • introduce the Java programming language• develop a simple Java application
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Introduction to module
• focus on developing applications using Java • each week you are expected to attend
• 2 lectures – to receive new concepts about programming
• 2 tutorials – to practice the new concepts in Java
• weekly sessions:• presented with new material• opportunity to practise new skills• ask for help with problems• exercises to complete
01 Introduction 4
Emphasis on learning• your goal is to learn about programming• our goal is to help you learn
• you have many resources to help achieve your goal
• lecturers – ask them many questions• lecture materials – use them often• tutorial exercises – aim to do them all• Blackboard, books, and the Internet
• take time to learn• 150 hours for this module• 48 hours in class – lectures and tutorials• 102 hours out of class
• finish the tutorial exercises each week; don’t get behind• read books and web sites about Java
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01 Introduction 5
Programmingis a
practical skillthat is
masteredby
doing it,not just
reading about it!
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Assessment
• 100% coursework• exercises build into portfolio
• your responsibility to:• attempt as many exercises as possible• include in your portfolio what is indicated in
specification• keep portfolio up-to-date
• 3 in-class tests • using Blackboard• questions about material presented in lectures• questions about your portfolio• you will need your electronic portfolio available
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Your portfolio
• your portfolio will need to be on electronic media• use the H: drive or a pen drive• make sure you organise and index your work• you will need to refer to it quickly and easily in the
tests• make sure you have a back-up
• tutorial worksheets indicate what to include• do as many tutorial exercises as possible• you will not know which exercises will feature in the
in-class tests
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Introduction to Java
• high level object oriented programming language
• designed to be:• simple• object oriented• distributed• robust• secure• architecture-neutral• portable• multithreaded
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What is computer programming?
• writing solutions to problems in a language that the computer can understand and execute
• several stages:• identify the problem
• understand the problem – analysis
• describe the solution - design
• write the solution in a programming language - coding
• evaluate the solution and improve it if necessary - testing
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Programming lifecycle
Identify problem
Understand the problem
Describe the solution
Program the solution
Test the program
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Program development stages
Write / edit source code
Compile source code into bytecode(computer understandable form)
Run program (bytecode)
javac
java
Hello.java
Hello.class
Results on screen
syntax errors
logic errors
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A Simple Java Application
//output Hello Worldpublic class Hello{ public static void main (String[] args) { System.out.println ("Hello World"); System.out.println ("Welcome to Java"); }}
Comment - ignored when program runs
this line is always written like this
output a message to console window
class name
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Write source code
• program can be written using any simple editor • can use Notepad, Wordpad• source file must be saved with an extension
of .java
File name has the form:<classname>.java
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Source code structure
• the first line is a comment indicated by //• comments are ignored when the program is executed• all Java code must be in a class• every class has:
• a header that names it• a body enclosed by { } that defines what it does
• code must be saved in a file called Hello.java
public class Hello{ //all code must be placed inside the braces}
Class header
Class body
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The main method
• classes are made up of at least one method • all Java applications have a main method• automatically run when the program is executed• contains statements to perform a task• every method has:
• a header that names it• a body enclosed by { } that defines what it does
public static void main (String[] args){ //all code must be placed inside the braces}
Method header
Method body
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Program statements
• the main method contains statements• each statement is terminated with ;
System.out.println ("Hello World");System.out.println ("Welcome to Java");
• these statements are method calls to the println method which is found in the System.out class
• all method calls are followed by parameters enclosed by ( )
• brackets must be included even if there are no parameters
• the println method has a string parameter which will be output
• strings are enclosed by ""
Class bodySemicolons
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Pitfalls - programming
• Java is case sensitive• Hello and hello are not the same• main and Main are also different
• every statement finishes with ;• headers are not statements – so no ;• program blocks are bracketed using { }• method names are always followed by ( )• strings are enclosed by ""
• compilers are very fussy – you must be accurate
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Compiling a Java application
• Java source code is in a human-readable format
• compiler:• checks that code is grammatically correct• converts valid code into bytecode which can be
executed by the computer if there are no errors• produces a .class file if there are no errors
• Sun provide a compiler called javac• invoked from the command prompt• javac Hello.java
• any errors will be displayed in window• no output means no errors
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Executing a Java application
• bytecode is executed using interpreter provided by Sun
• invoked from the command prompt• java Hello
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Pitfalls – compiling and running
• file name must be same as class name in code with .java as the extension• public class Hello• filename Hello.java
• the extension must be specified when file is compiled:• javac Hello.java
• the extension must NOT be specified when the class is interpreted• java Hello
Class name
File name
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Summary
In this session we have:• covered the module assessment requirements• looked at the structure of a Java application• introduced the main method• seen how to output strings to the screen• written, compiled and executed a Java application
In the next session we will:• look at using data within our programs
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