java introduction

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Introduction to JavaIntroduction to Java
Version 1.0Version 1.0

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Course ObjectiveCourse Objective
• The Objective of Java course is:The Objective of Java course is:
– To understand basic programming concepts using JavaTo understand basic programming concepts using Java
syntax.syntax.
– To appreciate OOP concepts and encourage problemTo appreciate OOP concepts and encourage problem
solving using OOP techniques.solving using OOP techniques.
– To understand various Java API and how to use themTo understand various Java API and how to use them
effectively in projects.effectively in projects.
– To understand the need for exception handling and howTo understand the need for exception handling and how
to use in Java environment.to use in Java environment.

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What is Java?What is Java?
• Java is both:Java is both:
– A Programming languageA Programming language
– A PlatformA Platform

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The Java ProgrammingThe Java Programming
LanguageLanguage
• Java is an Object Oriented Programming language.Java is an Object Oriented Programming language.
• Java’s syntax is similar to C / C++ syntax.Java’s syntax is similar to C / C++ syntax.
• Java is both compiled and interpreted.Java is both compiled and interpreted.
• The intermediate form is called Java byte code, which isThe intermediate form is called Java byte code, which is
platform independent.platform independent.
• Byte codes are interpreted by JVM during runtime.Byte codes are interpreted by JVM during runtime.

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Java PlatformJava Platform
• The Java Platform has twoThe Java Platform has two
components:components:
–The Java Virtual Machine (JVM)The Java Virtual Machine (JVM)
–The Java Application ProgrammingThe Java Application Programming
Interface (Java API)Interface (Java API)

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The Java PlatformThe Java Platform
• The Java VM is base for Java platform and isThe Java VM is base for Java platform and is
ported onto various hardware-based and OS basedported onto various hardware-based and OS based
platforms.platforms.
• The Java API is a large collection of ready-made,The Java API is a large collection of ready-made,
frequently used class libraries, stored in packages.frequently used class libraries, stored in packages.

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The Java EnvironmentThe Java Environment
Java Program
Java Virtual machine
Native OS / Platform
Java API
JAVA
PLATFORM

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A Simple Java ProgramA Simple Java Program
/** This is our first Java Program *//** This is our first Java Program */
class FirstClassclass FirstClass
{{
public static void main(String args[])public static void main(String args[])
{{
System.out.println(“Hello World.”);System.out.println(“Hello World.”);
}}
}}

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Compiling and Running in EclipseCompiling and Running in Eclipse

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Java Data TypesJava Data Types
• Two major data typesTwo major data types
– PrimitivePrimitive
• Because java program has to run on differentBecause java program has to run on different
architecture and OS, the size of the data shouldarchitecture and OS, the size of the data should
remain same. Otherwise, on different machines theremain same. Otherwise, on different machines the
output will be differentoutput will be different
– ReferenceReference
• All objects are of type reference data type. JavaAll objects are of type reference data type. Java
doesn’t allow directly to access memory. But objectsdoesn’t allow directly to access memory. But objects
are refered by pointers only.are refered by pointers only.

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Primitive Data TypesPrimitive Data Types
• IntegersIntegers
–bytebyte (8 bit)(8 bit)
–shortshort (16 bit)(16 bit)
–intint (32 bit)(32 bit)
–longlong (64 bit)(64 bit)

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Primitive Data TypesPrimitive Data Types
• Real NumbersReal Numbers
– floatfloat (32 bit)(32 bit)
– doubledouble (64 bit)(64 bit)
• Other TypesOther Types
– charchar (16 bit)(16 bit)
– booleanboolean (true / false)(true / false)

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Reference Data TypesReference Data Types
• Examples:Examples:
– ArraysArrays
– StringsStrings
– ObjectsObjects
– InterfacesInterfaces
• The name reference means a pointer in the memory. AllThe name reference means a pointer in the memory. All
objects are referred by their memory location only. Butobjects are referred by their memory location only. But
user cannot directly access memory location.user cannot directly access memory location.
• Memory management is taken care by JVM itself.Memory management is taken care by JVM itself.

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Variable NamesVariable Names
• Variable names in Java are legal Java identifier comprisedVariable names in Java are legal Java identifier comprised
of a series of Unicode characters.of a series of Unicode characters.
• Variable names must not be Java keyword or a booleanVariable names must not be Java keyword or a boolean
literalliteral
• Same variable name should not appear twice within aSame variable name should not appear twice within a
scope.scope.

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Java OperatorsJava Operators
• Arithmetic OperatorsArithmetic Operators
+, -, *, /, %+, -, *, /, %
• Unary Arithmetic OperatorsUnary Arithmetic Operators
++, --++, --
• Relational and Conditional OperatorsRelational and Conditional Operators
>, >=, <, <=, ==, !=, &&, ||, !>, >=, <, <=, ==, !=, &&, ||, !
• Bitwise OperatorsBitwise Operators
>>, <<, >>>, &, |, ^, ~>>, <<, >>>, &, |, ^, ~
• Ternary Operator: ()?():()Ternary Operator: ()?():()

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Control FlowControl Flow
• Decision makingDecision making
– if-else, switch-caseif-else, switch-case
• LoopLoop
– for, while, do-whilefor, while, do-while
• ExceptionException
– try-catch-finally, throwtry-catch-finally, throw
• MiscellaneousMiscellaneous
– Break, continue, label:, returnBreak, continue, label:, return

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Arrays in JavaArrays in Java
• Java arrays are objects.Java arrays are objects.
• Array contains like-typed values.Array contains like-typed values.
• Array can contain both primitive and reference data types.Array can contain both primitive and reference data types.
• When used with reference data types, reference (memoryWhen used with reference data types, reference (memory
location) is only stored in arrays and not the real objects.location) is only stored in arrays and not the real objects.
• Java supports multidimensional arrays. They are nothingJava supports multidimensional arrays. They are nothing
but ‘array of arrays’.but ‘array of arrays’.

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Arrays in JavaArrays in Java
• Array DeclarationArray Declaration
– int myIntegers[];int myIntegers[];
– int[] myIntegers;int[] myIntegers;
• Array memory allocation:Array memory allocation:
– int myIntegers[] = new int[10];int myIntegers[] = new int[10];
• Array Initialization:Array Initialization:
– int myIntegers[] = {1,2,3,4,5};int myIntegers[] = {1,2,3,4,5};

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Strings in JavaStrings in Java
• A sequence of characters is encapsulated as a StringA sequence of characters is encapsulated as a String
object.object.
• Java uses ‘+’ operator for String concatenation.Java uses ‘+’ operator for String concatenation.
• Some useful String functions are:Some useful String functions are:
– s.length();s.length();
– s1.equals(s2);s1.equals(s2);
– s1.subString(int startIndex, int upTo);s1.subString(int startIndex, int upTo);

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SummarySummary
• In this session you learned about:In this session you learned about:
– Java Programming LanguageJava Programming Language
– Java PlatformJava Platform
– Java EnvironmentJava Environment
– First Java ProgramFirst Java Program
– Data TypesData Types
– OperatorsOperators
– Control FlowControl Flow
– Java Arrays and StringsJava Arrays and Strings

java introduction

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