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Getting Started with Java
This document provides an overview of getting started with Java. It discusses what Java is, its evolution and key features like object-oriented programming. It reviews object-oriented programming concepts and demonstrates how to implement Java classes. The document also covers setting up a Java development environment, compiling and running Java programs, and local Java user groups and resources for learning more.
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Getting Started with Java
- 1. 1 Getting Started with Java TrentonComputer Festival March 17, 2018 Michael P. Redlich @mpredli about.me/mpredli/
- 2. Who’s Mike? • BSin CS from • “Petrochemical Research Organization” • Java Queue News Editor, InfoQ • Ai-Logix, Inc. (now AudioCodes) • Amateur Computer Group of New Jersey 2
- 3. Objectives (1) • Whatis Java?? • Evolution of Java • Features of Java • Review of Object-Oriented Programming (OOP) 3
- 4. Objectives (2) • GettingStarted with Java • introduction to the Java class mechanism • how to implement Java classes • Live Demos (yea!) • Java Resources 4
- 5. What is Java? •“Java is C++ without guns, knives, and clubs.” James Gosling,“father” of Java, Sun Microsystems • “Java is simple, object-oriented, distributed, interpreted, robust, secure, architecture neutral, portable, high performance, multithreaded dynamic language.” Sun Microsystems 5
- 6. Evolution of Java(1) • Created by James Gosling (with Patrick Naughton) • Sun Microsystems • 1991 - originally named “Oak” • consumer applications • architecture agnostic • object-oriented 6
- 7. Evolution of Java(2) • 1994 - Project “*7” dissolved • but in the meantime... • 1995 - Java introduced at Sun World ’95 • HotJava browser 7
- 8. Features of Java •Object-Oriented Programming (OOP) Language • Documentation Generation • Applets and Applications • Comprehensive Exception Handling • Java Database Connectivity (JDBC) • Java Beans • Enterprise Java Beans • No pointers!! 8
- 9. OOP Review (1) •Programming Paradigm • Four (4) Main Attributes • data encapsulation • data abstraction • inheritance • polymorphism 9
- 10. OOP Review (2) •Abstract Data Type (ADT) • user-defined data type • use of objects through functions (methods) without knowing the internal representation 10
- 11. OOP Review (3) •Interface • functions (methods) provided in the ADT that allow access to data • Implementation • underlying data structure(s) and business logic within the ADT 11
- 12. OOP Review (4) •Class • Defines a model • Declares attributes • Declares behavior • Is an ADT • Object • Is an instance of a class • Has state • Has behavior • May have many unique objects of the same class 12
- 13. Advantages of OOP •Interface can (and should) remain unchanged when improving implementation • Encourages modularity in application development • Better maintainability of code • Code reuse • Emphasis on what, not how 13
- 14. Some Java Keywords •class • new • private, protected, public, package • try, throw, catch, finally • final • extends • implements • abstract • interface 14
- 15. Classes (1) • Auser-defined abstract data type • Extension of C structs • Contain: • constructor • data members and member functions (methods) 15
- 16. Classes (2) • Dynamicobject instantiation • Multiple Constructors: • Sports(); • Sports(String,int,int); • Sports(float,String,int); 16
- 17. Classes (3) • AbstractClasses • contain at least one pure virtual member function (C++) • contain at least one abstract method (Java) 17
- 18. Abstract Classes • Purevirtual member function (C++) • virtual void draw() = 0; • Abstract method (Java) • public abstract void draw(); 18
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- 21. 21 // Sports class(partial listing) public class Sports { private String team; private int win; public Sports() { // define default constructor here... } public Sports(String team,int win,int loss) { // define primary constructor here... } public int getWin() { return win; } }
- 22. 22 // Baseball class(partial listing) class Baseball extends Sports { public Baseball() { // define default constructor here... } Baseball(String team,int win,int loss) { // define primary constructor here... } }
- 23. Dynamic Instantiation • Objectcreation: • Baseball mets = new Baseball(“Mets”,97,65); • Access to public member functions: • mets.getWin(); // returns 97 23
- 24. Deleting Objects Baseball mets= new Baseball(“Mets”,97,65); // automatic garbage collection or: System.gc(); // explicit call 24
- 25. Java Development Kit (JDK) •Available from Oracle web site • java.sun.com • Java SE (standard edition) • latest version - Java 9.0.4 • Java 10 available on March 20, 2018 • Documentation in full HTML format 25
- 26. Working with Java(1) • Setup environment and path: • set JAVA_HOME=path • set PATH=%PATH%;%JAVA_HOME%bin • export JAVA_HOME=path • export PATH=$JAVA_HOME/bin 26
- 27. Working with Java(2) • Source code • .java extension • Intermediate bytecode • .class extension generated after successful compilation • Bytecode interprested by JavaVirtual Machine (JVM) 27
- 28. Working with Java(3) • Compile Java source code: • javac -Xlint:all -d path filename.java • Run the application: • java -classpath path filename 28
- 29. Working with Java(4) • Run the applet: • in browser via HTML file within <applet></ applet> tags • appletviewer path filename.html 29
- 30. Directories and Packages (2) •Consistent directory structure • source code (*.java) • byte code (*.class) • Map directories with package name • under the src folder 30
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- 33. Java IDEs (1) •IntelliJ IDEA 2017.3 •jetbrains.com/idea • stay tuned for version 2018.1 coming soon • Eclipse IDE •eclipse.org/ide 33
- 34. Java IDEs (2) •NetBeans 8.2 •netbeans.org • currently being moved from Oracle to Apache 34
- 35. Local Java UserGroups (1) • ACGNJ Java Users Group • facilitated by Mike Redlich • javasig.org • Princeton Java Users Group • facilitated byYakov Fain • meetup.com/NJFlex 35
- 36. Local Java UserGroups (2) • NYJavaSIG • facilitated by Frank Greco • javasig.com • PhillyJUG • facilitated by Martin Snyder, et. al. • meetup.com/PhillyJUG 36
- 37. Local Java UserGroups (3) • Capital District Java Developers Network • facilitated by Dan Patsey • cdjdn.com • currently restructuring 37
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- 39. Upcoming Events • ACGNJJava Users Group • Dr. Venkat Subramaniam • Monday, March 19, 2018 • DorothyYoung Center for the Arts, Room 106 • Drew University • 7:30-9:00pm • “Twelve Ways to Make Code Suck Less” 39
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- 41. Upcoming Events • March17-18, 2017 •tcf-nj.org • April 18-19, 2017 •phillyemergingtech.com 41