1. Advanced Programming in Java Peyman Dodangeh Sharif University of Technology Fall 2013 Lecture 1: Introduction to OOP Slides adapted from Steven Roehrig

2. Expected Background  “A one-semester college course in programming.”  I assume you can write a program in some language, understand variables, control structures, functions/subroutines.  If in doubt, let’s talk.

3. Course Outline  Week 1: Background, basics of O-O, first Java program, programming environments  Week 2: Raw materials: types, variables, operators, program control  Week 3: Classes: declarations, constructors, cleanup & garbage collection  Week 4: Packages, access specifiers, finals, class loading

4. Course Outline (cont.)  Week 5: Polymorphism, abstract classes, design patterns  Week 6: Interfaces & extends, inner classes, callbacks via inner classes  Week 7: Applets, Applications, Swing  Week 8: Graphics and Multimedia  Week 9: Arrays, container classes, iterators

5. Course Outline (cont.)  Week 10: Exception handling, threads  Week 11: Java I/O, networking  Week 12: JDBC and object persistency

6. Administrative Details (cont.)  Midterm and final exams  Homework + Quiz + Projects: 50%  Midterm exam: 20%  Final exam: 30%  I will give one A+.

7. Administrative Details (cont.)  Everything is attached to the syllabus. Don’t look for assignments, etc. on Blackboard. Look at the syllabus!  Homework usually weekly.  Submission instructions with each assignment, usually printed listings and a zip file.  Printing slides? Three to a page, at least. Save a tree! Remove the PowerPoint background before printing. Save toner!

8. Administrative Details (cont.)  Attendance is not required, but…  …you are responsible for everything said in class.  I encourage you to ask questions in class. Don’t guess, ask a question!

9. My Policy on Cheating  Cheating means “submitting, without proper attribution, any computer code that is directly traceable to the computer code written by another person.”  I give students a failing course grade for any cheating.  This doesn’t help your job prospects.

10. My Policy on Cheating  You may discuss homework problems with classmates, after you have made a serious effort in trying the homework on your own.  You can use ideas from the literature (with proper citation).  You can use anything from the textbook/notes.  The code you submit must be written completely by you.

11. Course Etiquette  Etiquette is “conduct in polite society”  No cell phones  No random comings and goings  If you are sleepy, go home  If you want to read email or surf the Web, please do it elsewhere

13. Object Oriented Programming  Problem Space the place where the problem exists such as a business  Solution Space the place where you’re implementing that solution such as a computer  The effort required to perform this mapping. E.g. think about a library, or a phonebook program

14. Object Oriented Approach  OOP lets the programmer represent problem space elements  The elements in the problem space and their representations in the solution space are referred to as “objects”

15. OOP  The program is allowed to adapt itself to the lingo of the problem by adding new types of objects  when you read the code, you’re reading words that also express the problem. 15

16. OOP (2)  OOP allows you to describe the problem in terms of the problem  Rather than in terms of the computer  Objects in your code are similar to real objects  Recall the sample programs: phonebook and library 16

17. O-O Languages (Alan Kay)  Everything is an object.  A program is a bunch of objects telling each other what to do, by sending messages.  Each object has its own memory, and is made up of other objects.  Every object has a type (class).  All objects of the same type can receive the same messages.

18. Objects  An object has an interface, determined by its class.  A class is an abstract data type, or user- defined type.  Designing a class means defining its interface.

19. Built-In Types  Think of an int … What is its interface? How do you “send it messages”? How do you make one? Where does it go when you’re done with it?  In solving a computational problem, the goal is to Dream up useful classes, and Endow them with appropriate characteristics.

20. Example  Suppose I’ve defined this class in Java:  To make one, I type Light lt = new Light();  If I want switch on My Lamp, I say lt.on();

21. But Why Not Just…  This is legal, but just makes a “reference variable” named lt  This variable can refer to any Light object, but currently refers to nothing  The operator new actually causes an object to be created, so we tell it what kind we want Light lt;

22. Designers Design, Users Use  The interface is the critical part, but the details (implementation) are important too.  Users use the interface (the “public part”); the implementation is hidden by “access control”.

23. Object Oriented Languages  Smalltalk The first successful object-oriented language One of the languages upon which Java is based  Java  C++  C##

24. Why So Many Languages?  Bring the language “closer” to the problem.  But 4GLs are typically focused on specialized domains (e.g., relational databases).  We want a language that is general purpose, yet can easily be “tailored” to any domain.

25. Java History  Java was created in 1991  by James Gosling in Sun Microsystems  Initially called Oak in honor of the tree outside Gosling's window  Its name was changed to Java because there was already a language called Oak.  Sun Microsystems released the first public implementation as Java 1.0 in 1995  Java syntax is similar to C and C++.

26. Java Motivation  The need for platform independent language  To be embedded in various consumer electronic products like toasters and refrigerators  Platform independent?! Hardware Operating System

27. Java Motivation (2)  At the same time, the World Wide Web and the Internet were gaining popularity.  Java could be used for internet programming.  Why? Platform independence  Creation of Applets

28. The Java technology is:  A programming language Java can create all kinds of applications  A development environment A compiler (javac) An interpreter (java) A documentation generator (javadoc) …  Compare it to C++

29. High-Level Languages

30. Java Virtual Machine

31. Compile and Execution Stages  Compare to C++ and Assembly .NET Framework Sharif University of Technology

32. Java is Popular  Some reports on programming languages popularity According to Job advertisements Book sales Finding code on the web …

33. Characteristics of Java  Java is simple  Java is object-oriented  Java is architecture-neutral  Java is portable  Java is interpreted  Java is multithreaded  Java is secure  Java is robust

34. First Example  Create a file named First.java Java class files have.java extension Note to naming convention  Copy this lines to the file Note: File name and class name should be the same.

35. The Major Issues  Editing Use any text editor you like (not a word processor!); save as HelloDate.java  Compiling From a DOS or UNIX command line, type > javac HelloDate.java This should produce the file HelloDate.class  Running Again from the command prompt, type > java HelloDate

36. Assignment # 0  Download and install JDK http://www.oracle.com/technetwork/java/javase/downloads/index.html JDK 7  Write a program that prints your name on the console  Compile and run the program

37. Further Reading  Read Java page on Wikipedia http://en.wikipedia.org/wiki/Java_(programming_language)  Google this terms and phrases: Java Java Mobile JVM Byte code Java Sun Java and C++ Java and C#

38.  The End.