Java language: a gentle introduction
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This document provides an introduction to the Java programming language. It discusses key concepts such as the Java Virtual Machine (JVM), the Java Runtime Environment (JRE), and the Java Development Kit (JDK). It also introduces object-oriented programming concepts like classes, objects, interfaces, encapsulation, inheritance, and polymorphism. The document includes examples of a simple "Hello World" Java program and provides steps for writing, compiling, and running a Java file. It discusses some of the features of Java like being simple, object-oriented, interpreted, architecture neutral, portable, robust, distributed, secure, dynamic, concurrent, and having automatic memory management via garbage collection.
![My first Java program
1. public class Hello {
2. // entry point
3. public static void main(String[] args){
4. System.out.println("Hello World!");
5. }
6. }](https://image.slidesharecdn.com/javalanguage-agentleintroduction-110303101914-phpapp02/85/Java-language-a-gentle-introduction-31-320.jpg)
![My first Java program
1. public class Hello {
2. // entry point
3. public static void main(String[] args){
4. System.out.println("Hello World!");
5. }
6. }](https://image.slidesharecdn.com/javalanguage-agentleintroduction-110303101914-phpapp02/85/Java-language-a-gentle-introduction-35-320.jpg)
![My first Java program
1. public class Hello {
2. // entry point
3. public static void main(String[] args){
4. System.out.println("Hello World!");
5. }
6. }](https://image.slidesharecdn.com/javalanguage-agentleintroduction-110303101914-phpapp02/85/Java-language-a-gentle-introduction-36-320.jpg)
![My first Java program
1. public class Hello {
2. // entry point
3. public static void main(String[] args){
4. System.out.println("Hello World!");
5. }
6. }](https://image.slidesharecdn.com/javalanguage-agentleintroduction-110303101914-phpapp02/85/Java-language-a-gentle-introduction-37-320.jpg)
![My first Java program
1. public class Hello {
2. // entry point
3. public static void main(String[] args){
4. System.out.println("Hello World!");
5. }
6. }](https://image.slidesharecdn.com/javalanguage-agentleintroduction-110303101914-phpapp02/85/Java-language-a-gentle-introduction-38-320.jpg)
Java language: a gentle introduction
- 1. JAVA LANGUAGE: a gentle introduction [email protected]
- 2. I n t r o du c t i o n G e t t i ng S t a r t e d Object Oriented
- 3. P a rt 1 In t rod u c ti o n
- 5. 1991 OAK
- 6. January 23 1996 version 1.0 http://www.java.com/en/javahistory
- 7. INTRODUCTION to JAVA UNIVERSE
- 8. Wh a t’ s J A V A ?
- 9. Language
- 11. Standard Tools
- 13. F ea tu r e s
- 14. Simple
- 15. Object Oriented
- 16. Interpreted
- 18. Portable
- 19. Robust
- 20. Distributed
- 21. Secure
- 22. Dynamic
- 23. Concurrent
- 24. Rich
- 27. JD K Java AP I JR E JV M
- 28. JRE JDK (Java Runtime environment) (Java Development Toolkit) It is an implementation of the Java It is a bundle of software that you can Virtual Machine* which actually use to develop Java based executes Java programs. applications. Java Run Time Environment is a plug- Java Development Kit is needed for in needed for running java programs. developing java applications. JRE is smaller than JDK so it needs JDK needs more Disk space as it less Disk space. contains JRE along with various development tools. JRE can be downloaded/supported JDK can be downloaded/supported freely from freely from java.com java.sun.com It includes JVM , Core libraries and It includes JRE, set of API classes, other additional components to run Java compiler, Webstart and applications and applets written in additional files needed to write Java Java. applets and applications.
- 29. “An imaginary machine that is Virtual Machine implemented by emulating it in software on a real machine. Code for the java virtual machine is stored in .class files, each on which contains code for at most one public class.” da “The Java Virtual Machine Specification”
- 30. Pa rt 2 G e t ti n g S t a r te d
- 31. My first Java program 1. public class Hello { 2. // entry point 3. public static void main(String[] args){ 4. System.out.println("Hello World!"); 5. } 6. }
- 32. My first Java program Step 1: Open a text editor Step 2: Open a console (prompt dos/unix) Step 3: Write the code in text editor Step 4: Save as Hello.java
- 33. My first Java program Step 5: Compile javac Hello.java
- 34. My first Java program Step 6: Execute java Hello
- 35. My first Java program 1. public class Hello { 2. // entry point 3. public static void main(String[] args){ 4. System.out.println("Hello World!"); 5. } 6. }
- 36. My first Java program 1. public class Hello { 2. // entry point 3. public static void main(String[] args){ 4. System.out.println("Hello World!"); 5. } 6. }
- 37. My first Java program 1. public class Hello { 2. // entry point 3. public static void main(String[] args){ 4. System.out.println("Hello World!"); 5. } 6. }
- 38. My first Java program 1. public class Hello { 2. // entry point 3. public static void main(String[] args){ 4. System.out.println("Hello World!"); 5. } 6. }
- 39. Pa rt 3 Object Oriented
- 40. Par o gr a m m i n g P ar a d i gm s
- 41. Processes
- 42. Machine
- 43. EXAMPLE: ORANGE SQUEEZER Rube Goldberg, Inventions of Professor Lucifer Butts, 1932
- 44. “… nel progettare una sequenza codificata, quello che bisogna avere innanzitutto in mente non è l’apparenza originale della sequenza, ma piuttosto il suo funzionamento e il suo continuo cambiamento mentre il processo che essa controlla procede nel suo corso. … È dunque consigliabile incominciare la progettazione dalla fine, e cioè progettare per prima cosa il corso del processo e la relazione delle sue fasi successive con il codice che cambia, e quindi estrarre la sequenza codificata come operazione successiva.” Goldstine & Von Neumann, 1947
- 45. “… Questi “linguaggi di Von-Neumann” creano dei blocchi stradali mentali enormi e non necessari nel pensare i programmi e nel creare le combinazioni di alto livello richieste da una metodologia di programmazione veramente potente. …” John Backus, 1978
- 46. Things
- 47. Object Oriented
- 48. O b j e c ts ?
- 49. Class
- 50. Objects
- 51. Interface
- 52. C on c e pt s A nd F ea tu r e s
- 53. Classification
- 54. Activation
- 55. Encapsulation
- 56. Information Hiding
- 57. Inheritance
- 58. Composition
- 59. Polymorphism
- 60. Taxonomies
- 62. Reuse