- מבחן. - 4 עבודות ב- JAVA. הגשה בזוגות דרך ה- System Submission

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2 - מבחן. - 4 עבודות ב- JAVA 60% 40% הגשה בזוגות דרך ה- System Submission 2

3 UML Class Diagrams Packages Class Path JAR Files חלק ראשון: חלק שני: 3

4 An abstraction of software features A structure that singles out selected features Independent from other software elements Usually visual (diagrammatic) 4

5 The Unified Modeling Language (UML) is a widely accepted standard for software specification and design. It s a modeling Language. Why do engineers build models? To understand (Means for knowledge acquisition) To communicate better (Means for knowledge transfer) (תחליף - (Surrogates To predict interesting things about the system To specify the implementation of the system (Blueprints) Building models is realized by selecting statements through abstraction, i.e., reduction of information preserving properties relative to a given set of concerns. From: Bran Selic, UML2 MoDELS

6 + OCL (Object Constraint Language) 6

7 Shows the classes of a system: Their interrelationships: Inheritance (is a) Association Aggregation (has a) [Class and Student] Composition (has a) [House and Room] Their Constraints 7

8 Class A group of objects (instances) that have common: Properties. Behavior. Relationships to other objects. Semantics. Information For Example: 8

9 Three types: Public (everyone) Protected (class, subclass and members of the same package) Private (class only) For Example: Circle - centrex:int - centrey:int + draw() # move(int X, Int Y) 9

10 Association is a relationship between classes which is used to show that instances of them could be either linked to each other or combined logically or physically. For example, a person works for a company: Role Person employee works for employer Company Association Name This type of association is a plain association. 10

11 A Student can take up to five Courses. Student has to be enrolled in at least one course. Up to 300 students can enroll in a course. A class should have at least 10 students. Student takes 1..5 Course 11

12 Association VS attribute Associations are the essence of object-oriented modeling. Connections between objects are always modeled as links. Attributes provide additional (secondary) information about identified objects. Attribute heuristic rule: If it s important it s not an attribute! 12

13 Roles VS Objects A Person has exactly two Parents and any number of children 13

14 UML allows us to model other kinds of relationships between classes and objects Allows us to staticly model a realistic state of the system and makes it simpler to understand the model Generalization/SubTyping (is a) Realization Aggregation (has a) Composition (has a) 14

15 שעת- אוניברסיטה Inheritance relationship. With this relationship, we can collect the properties and services which are shared between some classes and extract them to a class called a SuperType Every class that was a part of this process becomes a SubType and inherits the properties, services and relationships from the SuperType class (and of course can extend them). +givepractice() עובד אוניברסיטה שם- מחלקה- ותק- +ParkTheCar() מרצה תחום מחקר- דרגה- מתרגל קבלה +givelecture() 15

16 דרגה- מונחה- מנחה- חברה מעסיקה טכנאים חלקם מומחים וחלקם מתמחים. לכל מתמחה יש לפחות מנחה אחד. מומחה הוא טכנאי שיודע הכל בתחום ההתמחות שלו. מתמחה יכול להיות מנחה של מתמחה אחר כל עוד אין מעגליות בתחום ההתמחות. כללים: לכל מתמחה יש רק מנחה אחד כל מומחה יכול להנחות מנחה רק בתחום אחד מהו תחום התמיכה? מנחה יכול להנחות מתמחים אחרים שיכולים להנחות אותו. יתכנו מומחה ומתמחה באותה הדרגה. מתמחה טכנאי מומחה 1 0..* 16

17 This relationship describes a Whole and it s Parts. Each part can only be in one Whole. It describes something and it s components. Circle Polygon Point 1 1 ספר * כריכה תוכן עניינים פרק אינדקס 17

18 This relationship is similar to Composition. It describes the relationship between the Parts of a Whole. The difference is, here the parts can be parts of another Whole. Intuitively, one can think that in composition, the Whole can t survive without one of its parts. In Aggregation, it can. קבוצה 0..* 0..* שחקן 18

19 A realization relationship indicates that one class implements a behavior specified by some interface An interface can be realized by many classes A class may realize many interfaces LinkedList <<interface>> List LinkedList List ArrayList 19

20 Name* Car * - enginesize : int - maxspeed : int Fields # getmaxspeed() : int Non Abstract Methods Abstract methods * + drive() * 20

21 Authorization in a relational DBMS A user may own multiple tables The owner of a table may authorize 1 or more other users access to the table An authorized user may grant more permissions. * 21

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24 דוגמא לחברה יש בין 20 עד 120 עובדים. כל עובד מועסק בחברה אחת בלבד. ישנם 2 סוגים של עובדים: פשוט ובכיר. לכל עובד פשוט יש מנהל אחראי שהוא עובד בכיר. כל עובד בכיר יכול להיות מנהל ל 0 עד 5 עובדים פשוטים

25 Web based UML tool 25

26 Packages are the Java mechanism to prevent name collisions between classes. java.util.list java.awt.list! Package rules: Each class belongs to a package (which will hold related classes) Package may have sub-packages A package path is dot-separated foo.goo.boo Class Boo, sub-package goo, package foo Sub-packages has no special properties or privileges 26

27 Package declaration (In the beginning of the class) package foo.goo; class Boo {...} Or, let eclipse do it for you: Importing classes from other packages import java.util.array // Import only the Array class import java.util.*; // All classes in java.util 27

28 When looking for a class, the JRE looks for a.class file in directories that match the package path. Intuitively, Sub-package = Sub-directory. The root directory is the classpath. If, for example, we want to find the class foo.goo.boo in the directories tree +-classpath foo goo -X.class -Y.class -Boo.class 28

29 Classpath is a parameter set either on the command-line, or through an environment variable that tells the Java Virtual Machine or the Java compiler where to look for user-defined classes and packages. A classpath can contain several roots. Finding the previous class in the Classpath= A:B:C Root A +-A +-fi +-fy -Fum.class -... Root B +-B foo goo -X.class -Y.class Root C +-C foo goo -Z.class -Boo.class 29

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31 Jar files are the Java equivalent to libraries and executables. A jar file is a zip archive that contains:.class files Other needed resources (images, config files) A manifest file (optional) MANIFEST.MF Source files (optional) 31

32 The manifest file is a text file with key:value properties. The JRE reads these properties when it loads the.jar file. Important properties in a jar manifest: Manifest-Version: For backward compatibility. (e.g Manifest-Version: 1.0) Main-Class: The class containing the main method to run. (e.g Main-Class: a.b.c.foo) Class-Path: Space-separated list of other class paths to use. (e.g Class-path: mylib1.jar mylib2.jar) See for details on jar and manifest specifications. 32

33 Jar files as Java shared libraries Including a jar file in a classpath will cause the JRE to look in the archive for classes and resources, as if it was another directory. Jar files as Java executables You can run a jar file by running: java -jar hello-world.jar (Or double-click on it, in some systems) The Java Runtime will load all the content of the jar, including its classpath, and will run the main class that is written in the manifest. 33

34 Creating a jar file using the command-line tool: jar cf <jar-file> <manifest-file> files... 34

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