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© Tomáš Kozel, Pavel Čech Programming I Pavel Čech Faculty of Informatics and Management University Hradec Kralove /pc/www.

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Presentation on theme: "© Tomáš Kozel, Pavel Čech Programming I Pavel Čech Faculty of Informatics and Management University Hradec Kralove /pc/www."— Presentation transcript:

1 © Tomáš Kozel, Pavel Čech Programming I Pavel Čech Faculty of Informatics and Management University Hradec Kralove /pc/www

2 © Tomáš Kozel, Pavel Čech 2 Content Introduction into programming Object oriented modeling Object oriented programming Programming in Java

3 © Tomáš Kozel, Pavel Čech 3 Objectives Introduce students to OOP in Java Apply apply knowledge acquired in ALGD Use advanced tools for application development

4 © Tomáš Kozel, Pavel Čech 4 Resources McConnell:Rapid Development – Microsoft Press 1996 McConnell:Code Complete – Microsoft Press 1994 Electronic publications The Java Tutorial, Java SDK Documentation - Thinking in Java -, 3. edition

5 © Tomáš Kozel, Pavel Čech 5 Tools Java 2 SDK – basic package for programming in Java Eclipse – IDE for programming in JAVA ArgoUML – CASE Tool for object oriented modeling in UML These tools can be downloaded from> (uid: student, pwd: prox) All tools a free

6 © Tomáš Kozel, Pavel Čech 6 Terminlogy Program = sequence of commands describing some action Process = program being executed (running) program Processor – device capable of executing a program Data – certain kind of objects, that are appropriately transformed by the program

7 © Tomáš Kozel, Pavel Čech 7 Terminology (cont.) Source code – programming code written in a certain programming language Target code – binary code, that is created by compilation of source code – is executable Byte code(Java) – intermediate code that is create by compilation but it is run by runtime environment (JRE, JVM) Library – group of files that contain subroutines and classes and that can be used in our program

8 © Tomáš Kozel, Pavel Čech 8 Terminology (cont.2) Data type – determines type and the size of value in variables. Indirectly determines the set of operations that can be applied to the value. Variable – “named” block of memory in RAM for storing values. The size of the memory block depends on the data type of the value. Constant – the same as variable but it is not allowed to changed the value (it is read only). The constant can be assigned value only once and that can be only read.

9 © Tomáš Kozel, Pavel Čech 9 Programming language the means of communication between computer and the programmer the means of describing an algorithm needs to be understandable for both sides Taxonomy Lower level programming lang. Higher level …

10 © Tomáš Kozel, Pavel Čech 10 Types of prog. lang. Structured Separation of data and operations Older by still commonly used In many cases faster and efficient C, Pascal, Basic,… Object oriented Modern Easily maintainable The code can be re-used Eiffel, Smalltalk, Java,... Hybrid Not strictly object oriented i.e. can also be structured (C++, Object Pascal - Delphi, Visual Basic...)

11 © Tomáš Kozel, Pavel Čech 11 Compiler =special kind of programs for conversion of source code into machine code Types Interpreter Compiler

12 © Tomáš Kozel, Pavel Čech 12 Interpreter source code output data Computer Interpreter input data

13 © Tomáš Kozel, Pavel Čech 13 Compiler developer’s computer source code input data output data user’s computer compiler target code

14 © Tomáš Kozel, Pavel Čech 14 The process of compilation Editor Compiler Linker (links program) OBJ code relative code Library Target code Source code Debugger

15 © Tomáš Kozel, Pavel Čech 15 Running program in Java Compilation environment Run-time environment Source code (.java) Java compiler Byte code (.class) Local or network transmission of byte code Class Loader + Verifier of byte code Java libraries Java Interpreter Just-In-Time compiler Runtime system OS HW Java Virtual Machine

16 © Tomáš Kozel, Pavel Čech 16 What is object … Objects real world - entities that can be found everywhere software – program entities that follow the rules of real world ones. By combination of sw. object we create object oriented programs (systems).

17 © Tomáš Kozel, Pavel Čech 17 Real world objects Have a name (object identity) Have properties (state) Do something (behavior)

18 © Tomáš Kozel, Pavel Čech 18 Where can we find objects? Thinking about a situation We can write some notes with description and processes in that situation. Noun can be objects. Verbs can be operations (behavior) of objects Objects that are not important when considering a given problem can be left out

19 © Tomáš Kozel, Pavel Čech 19 Object oriented programs (Alan Kay) 1. Everything is object. Objects stores data and we can ask for some services (performing an operation). 2. Program is a group of objects that comunicates (send messages = ask for services). 3. Each object has its own memory space and can consists of other objects. Complex objects can be divided into other objects. 4. Every object belongs to a class. 5. Every object of the same class has to understand the same messages and perform the same operations. Objects can belong into more classes through inheritance.

20 © Tomáš Kozel, Pavel Čech 20 Why use objects in programs? It is modern … They’re closer to reality Readable source code Advanced tools and languages Reusable Easily maintainable

21 © Tomáš Kozel, Pavel Čech 21 What objects can today? Behave Have properties Inherit from ancestors Adapt Communicate …

22 © Tomáš Kozel, Pavel Čech 22 Terminology revisited Object always something particular with identity called also instance (Trabant, Audi A6,...). Class type of objects, a group in which a set of objects belong. Describes general features common to all objects (instances) in a class (Car).

23 © Tomáš Kozel, Pavel Čech 23 UML.... tool ArgoUML Unified Modeling Language Graphical language for object modeling ClassObject MyFord:Car Car Color HP Go() Brake() Car attributes (data) methods (operations)

24 © Tomáš Kozel, Pavel Čech 24 Software objects have name (identity), state, behavior name is determined by identifier, state is described by attributes, behaviour is realized by methods

25 © Tomáš Kozel, Pavel Čech 25 Basic OOP principles Abstraction Encapsulation Inheritance Polymorphisms Communication (messages)Communication (messages) AssociationAssociation Aggregation (composition)Aggregation (composition)

26 © Tomáš Kozel, Pavel Čech 26 Abstraction = separation of important and unimportant aspects based on a given problem Example: Calculator from the point of view of the student Important aspects: Range and precision of numbers Number and types of operations Can be kept secret during the test Unimportant: Number of chips on a system board Type of processor Exact algorithm of every operation

27 © Tomáš Kozel, Pavel Čech 27 Encapsulation = data and operation forms a atomic whole that cannot be separated Data (properties, state) of object and operations are dependent and influence each other. Not all features of objects are propagated to outside (Information hidding) Data – attribures of an object Operation – methods of an object Example: An angry man (state) is more noisy (behavior) than the calm one.

28 © Tomáš Kozel, Pavel Čech 28 Information hiding Every object can have private elements (attributes, methods) than cannot be seen or influence from the outside of the object (Information hiding). These elements are hidden behind so called public interface. Example: state and properties of a man‘s intestines Public interface Private state „Doughnut“ diagram

29 © Tomáš Kozel, Pavel Čech 29 Communication (messaging) Objects communicate by sending messages. As a consequence of receiving a message some operation is performed (message passing = method invocation)

30 © Tomáš Kozel, Pavel Čech 30 Association = represents a general binary relation between two classes Each class in association has its role For each object with a role we can determine multiplicity (cardinality) of that relation Example: Class Student is in association with the class Faculty. The student „studies“ and the faculty is „studied by“. Multiplicity: Many students (n or *) can study only one faculty.

31 © Tomáš Kozel, Pavel Čech 31 Aggregation = special kind of association that represents the relation „part of“ Object can contain other objects. Such objects are created by aggregating other objects. If the use of part objects is exclusive in aggregation we talk about composition. Example: Composition: TV x Chip Aggregation: Student x Lab

32 © Tomáš Kozel, Pavel Čech 32 Association in UML FacultyStudent studuje 1..* 1 Association LabStudent TVTVChip Aggregation Composition

33 © Tomáš Kozel, Pavel Čech 33 Inheritance = ability of objects to inherit attributes and behavior from ancestors (it is so called object evolution) ie. that attributes and behavior can be further extended and modified Example: Parent -> Children Machine -> Vehicle -> Car

34 © Tomáš Kozel, Pavel Čech 34 Inheritance in UML MachineVehicleCarTruck

35 © Tomáš Kozel, Pavel Čech 35 Class attributes Attributes are common must be present for all objects of a particular class State of object is given by values of attributes Sometimes called data, properties Example: Color, Brand, horse power

36 © Tomáš Kozel, Pavel Čech 36 Class methods Specify behavior Sometimes called operation or services It is custom to hide attributes and use so called access method to set or retrieve values Access methods Selectors – reading/retrieving values Modifiers – setting/writing values

37 © Tomáš Kozel, Pavel Čech 37 Information hiding Rule: None of the attributes should be directly accessible from the outside world ->(Black Box) Attributes Method

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