Connect. Collaborate. Innovate.                               Java Programming Basic                                      ...
Connect. Collaborate. Innovate.                                     Gentle Reminder:                                 “Swit...
Connect. Collaborate. Innovate.                Agenda                •     What JAVA is for?                         –    ...
Connect. Collaborate. Innovate.                What JAVA does for you?                • Hardware Systems                  ...
Connect. Collaborate. Innovate.                Why Portability?                • Softwares Portability                    ...
Connect. Collaborate. Innovate.                Why Portability?                • There are different hardware and operatin...
Connect. Collaborate. Innovate.                • Example C program                               void main()              ...
Connect. Collaborate. Innovate.                Language & Libraries                • A “programming language” is about    ...
Connect. Collaborate. Innovate.                JVM                • A virtual machine (VM) is an abstract computer archite...
Connect. Collaborate. Innovate.                •     Java source code is compiled to byte-codes whose target architecture ...
Connect. Collaborate. Innovate.© Copyright GlobalLogic 2009                                 11                            ...
Connect. Collaborate. Innovate.                Exercise                • Write a Java program to print “Hello World!!!” on...
Connect. Collaborate. Innovate.                Classpath                • The Classpath is an argument (Environment variab...
Connect. Collaborate. Innovate.                Exercise                • Revisit the hello world program                • ...
Connect. Collaborate. Innovate.                Java Packages                • A Java package is a mechanism for organizing...
Connect. Collaborate. Innovate.                Exercise                • Move the hello world program in a package        ...
Connect. Collaborate. Innovate.                Data Types                • A data type is a set of values and the operatio...
Connect. Collaborate. Innovate.                Data Types                • Arrays                                    int[]...
Connect. Collaborate. Innovate.                Basic I/O                • I/O streams                               • An I...
Connect. Collaborate. Innovate.                Exercise                • To determine whether a given string is a palindro...
Connect. Collaborate. Innovate.                Garbage Collection                • Garbage collection (GC) is a form of au...
Connect. Collaborate. Innovate.                JavaDoc/Comments                Java comments are of three types           ...
Connect. Collaborate. Innovate.                               Q&A© Copyright GlobalLogic 2009                             ...
Connect. Collaborate. Innovate.                    “Thank You” for your learning contribution!           Please submit fee...
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Java programming basics

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Java programming basics

  1. 1. Connect. Collaborate. Innovate. Java Programming Basic Concepts Learning Facilitator: Date:© Copyright GlobalLogic 2009 1
  2. 2. Connect. Collaborate. Innovate. Gentle Reminder: “Switch Off” your Mobile Phone Or Switch Mobile Phone to “Silent Mode”© Copyright GlobalLogic 2009 2
  3. 3. Connect. Collaborate. Innovate. Agenda • What JAVA is for? – Software Portability – Why Portability Matters – Language and Libraries • Basic Concepts – JVM, Classpath – Packages – Data Types – JavaDoc/Comments – Garbage Collection • Example Java Application© Copyright GlobalLogic 2009 3 3
  4. 4. Connect. Collaborate. Innovate. What JAVA does for you? • Hardware Systems – Processor + memory + I/O devices (Platform to execute softwares) • Operating Systems – An operating system (OS) is a set of computer programs that manage the hardware and software resources of a computer. – Runs on top of hardware, so tightly attached with the hardware • Application Softwares – Runs on top of operating system, a subclass of computer software which address a particular objective e.g. Word-processors .. – Application made for one OS/hardware system may not run on another.© Copyright GlobalLogic 2009 4 4
  5. 5. Connect. Collaborate. Innovate. Why Portability? • Softwares Portability “Applications that are independent of all hardware and operating systems” You can compile a Java program on any system and run the resulting binary executable file on the same or any other system • “Software portability” refers to adapting a software to a new environment, without re-developing it. This reduces the re- development efforts.© Copyright GlobalLogic 2009 5 5
  6. 6. Connect. Collaborate. Innovate. Why Portability? • There are different hardware and operating systems • Even for one OS, there are numerous releases • Software portability is all about “Future-proofing” your Software investment “Future proofing” is a process of trying to anticipate future developments, so that appropriate actions can be taken to minimize negative consequences. • With application programs written in Java, you can change/upgrade OS and applications independently© Copyright GlobalLogic 2009 6 6
  7. 7. Connect. Collaborate. Innovate. • Example C program void main() { int arr[2]; printf(“%dn”, arr*3+); } • Run this on windows (using turbo c) • Run this on Unix (using gcc) • Compare the results© Copyright GlobalLogic 2009 7 7
  8. 8. Connect. Collaborate. Innovate. Language & Libraries • A “programming language” is about – Describing DATA – Describing STATEMENTS that work on DATA – Describing the ways the two can be put together • How expressions are formed • What statements look like • Java is a Object-oriented, strongly typed language. – Strongly typed languages specify one or more restrictions on how operations involving values having different data types can be intermixed. • Library (package) – Frequently reused code – Not an executable program, but contains executable code – Linking with programs address space© Copyright GlobalLogic 2009 8 8
  9. 9. Connect. Collaborate. Innovate. JVM • A virtual machine (VM) is an abstract computer architecture • Software on top of a real hardware • Can run the same application on different machines where the VM is available Java program C program v1 C program v2 Compiler C compiler and executor 1 JVM 1 JVM 2 JVM 3 C compiler and executor 2 Platform 1 Platform 2 Platform 3© Copyright GlobalLogic 2009 9 9
  10. 10. Connect. Collaborate. Innovate. • Java source code is compiled to byte-codes whose target architecture is the Java Virtual Machine (JVM) • Just-in-time (JIT) compiler provides compilation of byte-code to machine code© Copyright GlobalLogic 2009 10 10
  11. 11. Connect. Collaborate. Innovate.© Copyright GlobalLogic 2009 11 11
  12. 12. Connect. Collaborate. Innovate. Exercise • Write a Java program to print “Hello World!!!” on the command prompt (Use notepad) – Compile the program – Run the program© Copyright GlobalLogic 2009 12 12
  13. 13. Connect. Collaborate. Innovate. Classpath • The Classpath is an argument (Environment variable) that tells the Java Virtual Machine where to look for user-defined classes and packages in Java programs. • Setting CLASSPATH from command-line SET CLASSPATH=Dir; • Setting CLASSPATH in Windows via Control-panel© Copyright GlobalLogic 2009 13 13
  14. 14. Connect. Collaborate. Innovate. Exercise • Revisit the hello world program • Compiling and running the program from any other directory© Copyright GlobalLogic 2009 14 14
  15. 15. Connect. Collaborate. Innovate. Java Packages • A Java package is a mechanism for organizing Java classes into namespaces. • A package provides a unique namespace for the types it contains. • Classes in the same package can access each others protected members. • Packages are usually defined using a hierarchical naming pattern • Example – java.lang.*, com.globallogic.*© Copyright GlobalLogic 2009 15 15
  16. 16. Connect. Collaborate. Innovate. Exercise • Move the hello world program in a package com.globallogic.training.java • Now compile and execute the program© Copyright GlobalLogic 2009 16 16
  17. 17. Connect. Collaborate. Innovate. Data Types • A data type is a set of values and the operations on those values – For example, the Java "int" type is the set of 32-bit integers together with the operations "+", "*", "%", etc that operate over integers • A data type describes representation, interpretation and structure of values manipulated by algorithms or objects stored in computer memory or other storage device • Java has two groups of data types, primitive data types and object references. – primitive data types store actual data, – Java object references are variables which hold references to objects© Copyright GlobalLogic 2009 17 17
  18. 18. Connect. Collaborate. Innovate. Data Types • Arrays int[] anArray; anArray = new int[10]; OR int[] anArray = new int[10]; • String String greeting = "Hello world!"; character array char[] helloArray = { h, e, l, l, o, .}; String helloString = new String(helloArray); Basic operations length concat substr • int, float© Copyright GlobalLogic 2009 18 18
  19. 19. Connect. Collaborate. Innovate. Basic I/O • I/O streams • An I/O Stream represents an input source or an output destination. A stream can represent many different kinds of sources and destinations, including disk files, devices, other programs, and memory arrays. • Input stream • Output stream • Writing on console System.out.println(“...”); • Reading from console BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in.readLine();© Copyright GlobalLogic 2009 19 19
  20. 20. Connect. Collaborate. Innovate. Exercise • To determine whether a given string is a palindrome. – Input : a String to be read from console – Ouptput: true/false© Copyright GlobalLogic 2009 20 20
  21. 21. Connect. Collaborate. Innovate. Garbage Collection • Garbage collection (GC) is a form of automatic memory management. • The garbage collector or collector attempts to reclaim garbage, or memory used by objects that will never be accessed the application • The basic principle of how a garbage collector works is: – Determine what data objects in a program will not be accessed in the future – Reclaim the resources used by those objects • A key feature of Java is its garbage-collected heap, which takes care of freeing dynamically allocated memory that is no longer referenced.© Copyright GlobalLogic 2009 21 21
  22. 22. Connect. Collaborate. Innovate. JavaDoc/Comments Java comments are of three types – Line Comment //line comment – Block Comment /* block comment */ – JavaDoc Comment /** * ... */ • Javadoc is a tool for generating API documentation in HTML format from doc comments in source code© Copyright GlobalLogic 2009 22 22
  23. 23. Connect. Collaborate. Innovate. Q&A© Copyright GlobalLogic 2009 23
  24. 24. Connect. Collaborate. Innovate. “Thank You” for your learning contribution! Please submit feedback to help L&D make continuous improvement…… Dial @ Learning: Noida: 4444, Nagpur:333, Pune:5222, Banglore:111 E mail: learning@globallogic.com© Copyright GlobalLogic 2009 24

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