Learn Java - Java Tutorial for Beginners - Java Tutorial

Category: Education

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Learn JAVA tutorial - This Java tutorial is specially prepared for the Beginners who wants to learn Java programming language from the basics. This tutorial is prepared by Easy Web Solutions located in Panchkula that provides 6 months industrial training in Java, Android, IOS, PHP, ASP.NET, and Digital Marketing.


Presentation Transcript

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EASY WEB SOLUTION Instructor: Lavi Gupta 09803266066

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 Instructor: LAVI GUPTA M.T ech Computers ◦ Ofce: 351 TriCity PLAZZA Adj. Sec-20 Panchkula ◦ Ofce Phone: 9803266066 9501922388 ◦ Email: techlavigmail.com ◦ Ofce hours: Monday T o Fridays 10-7pm Or by appointment call: 09803266066 Instructor: Lavi Gupta 09803266066

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 Lecture: MWF 01:00 PM – 02:10 PM  Lab: W 02:30 PM - 04:20 PM Instructor: Lavi Gupta 09803266066

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 Midterm: 20  Final: 25  Programming Projects: 40  Homework and labs: 15 Instructor: Lavi Gupta 09803266066

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 Object-Oriented Software Development ◦ problem solving ◦ program design implementation and testing ◦ object-oriented concepts  classes  objects  encapsulation  inheritance  polymorphism ◦ graphical user interfaces Instructor: Lavi Gupta 09803266066

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• The Java Programming Language • Program Development • Object-Oriented Programming Instructor: Lavi Gupta 09803266066

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 A programming language specifes the words and symbols that we can use to write a program  A programming language employs a set of rules that dictate how the words and symbols can be put together to form valid program statements  The Java programming language was created by Sun Microsystems Inc.  It was introduced in 1995 and its popularity has grown quickly since Instructor: Lavi Gupta 09803266066

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 In the Java programming language: ◦ A program is made up of one or more classes ◦ A class contains one or more methods ◦ A method contains program statements  These terms will be explored in detail throughout the course  A Java application always contains a method called main Instructor: Lavi Gupta 09803266066

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public class Lincoln //----------------------------------------------------------------- // Prints a presidential quote. //----------------------------------------------------------------- public static void main String args System.out.println "A quote by Abraham Lincoln:" System.out.println "Whatever you are be a good one." Instructor: Lavi Gupta 09803266066

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public class MyProgram // comments about the class class header class body Comments can be placed almost anywhere Instructor: Lavi Gupta 09803266066

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public class MyProgram // comments about the class public static void main String args // comments about the method method header method body Instructor: Lavi Gupta 09803266066

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 Comments in a program are called inline documentation  They should be included to explain the purpose of the program and describe processing steps  They do not afect how a program works  Java comments can take three forms: // this comment runs to the end of the line / this comment runs to the terminating symbol even across line breaks / / this is a javadoc comment / Instructor: Lavi Gupta 09803266066

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 Identifers are the words a programmer uses in a program  An identifer can be made up of letters digits the underscore character _ and the dollar sign  Identifers cannot begin with a digit  Java is case sensitive - Total total and TOTAL are diferent identifers  By convention programmers use diferent case styles for diferent types of identifers such as ◦ title case for class names - Lincoln ◦ upper case for constants - MAXIMUM Instructor: Lavi Gupta 09803266066

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 The Java reserved words: abstract assert boolean break byte case catch char class const continue default do double else enum extends false final finally float for goto if implements import instanceof int interface long native new null package private protected public return short static strictfp super switch synchronized this throw throws transient true try void volatile while Instructor: Lavi Gupta 09803266066

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 Spaces blank lines and tabs are called white space  White space is used to separate words and symbols in a program  Extra white space is ignored  A valid Java program can be formatted many ways  Programs should be formatted to enhance readability using consistent indentation Instructor: Lavi Gupta 09803266066

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public class Lincoln2public static void mainStringargs System.out.println"A quote by Abraham Lincoln:" System.out.println"Whatever you are be a good one." Instructor: Lavi Gupta 09803266066

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The Java Programming Language Program Development Object-Oriented Programming Instructor: Lavi Gupta 09803266066

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 The mechanics of developing a program include several activities ◦ writing the program in a specifc programming language such as Java ◦ translating the program into a form that the computer can execute ◦ investigating and fxing various types of errors that can occur  Software tools can be used to help with all parts of this process Instructor: Lavi Gupta 09803266066

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 Each type of CPU executes only a particular machine language  A program must be translated into machine language before it can be executed  A compiler is a software tool which translates source code into a specifc target language  Often that target language is the machine language for a particular CPU type  The Java approach is somewhat diferent Instructor: Lavi Gupta 09803266066

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 The Java compiler translates Java source code into a special representation called bytecode  Java bytecode is not the machine language for any traditional CPU  Another software tool called an interpreter translates bytecode into machine language and executes it  Therefore the Java compiler is not tied to any particular machine  Java is considered to be architecture-neutral Instructor: Lavi Gupta 09803266066

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Java source code Machine code Java bytecode Bytecode interpreter Bytecode compiler Java compiler Instructor: Lavi Gupta 09803266066

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 There are many programs that support the development of Java software including: ◦ Sun Java Development Kit JDK ◦ Sun NetBeans ◦ IBM Eclipse ◦ Borland JBuilder ◦ MetroWerks CodeWarrior ◦ BlueJ ◦ jGRASP  Though the details of these environments difer the basic compilation and execution process is essentially the same Instructor: Lavi Gupta 09803266066

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 The syntax rules of a language defne how we can put together symbols reserved words and identifers to make a valid program  The semantics of a program statement defne what that statement means its purpose or role in a program  A program that is syntactically correct is not necessarily logically semantically correct  A program will always do what we tell it to do not what we meant to tell it to do Instructor: Lavi Gupta 09803266066

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 A program can have three types of errors  The compiler will fnd syntax errors and other basic problems compile-time errors ◦ If compile-time errors exist an executable version of the program is not created  A problem can occur during program execution such as trying to divide by zero which causes a program to terminate abnormally run-time errors  A program may run but produce incorrect results perhaps using an incorrect formula logical errors Instructor: Lavi Gupta 09803266066

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errors errors Edit and save program Compile program Execute program and evaluate results Instructor: Lavi Gupta 09803266066

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The Java Programming Language Program Development Object-Oriented Programming Instructor: Lavi Gupta 09803266066

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 The purpose of writing a program is to solve a problem  Solving a problem consists of multiple activities: ◦ Understand the problem ◦ Design a solution ◦ Consider alternatives and refne the solution ◦ Implement the solution ◦ T est the solution  These activities are not purely linear – they overlap and interact Instructor: Lavi Gupta 09803266066

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 The key to designing a solution is breaking it down into manageable pieces  When writing software we design separate pieces that are responsible for certain parts of the solution  An object-oriented approach lends itself to this kind of solution decomposition  We will dissect our solutions into pieces called objects and classes Instructor: Lavi Gupta 09803266066

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 Java is an object-oriented programming language  As the term implies an object is a fundamental entity in a Java program  Objects can be used efectively to represent real- world entities  For instance an object might represent a particular employee in a company  Each employee object handles the processing and data management related to that employee Instructor: Lavi Gupta 09803266066

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 An object has: ◦ state - descriptive characteristics ◦ behaviors - what it can do or what can be done to it  The state of a bank account includes its account number and its current balance  The behaviors associated with a bank account include the ability to make deposits and withdrawals  Note that the behavior of an object might change its state Instructor: Lavi Gupta 09803266066

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 An object is defned by a class  A class is the blueprint of an object  The class uses methods to defne the behaviors of the object  The class that contains the main method of a Java program represents the entire program  A class represents a concept and an object represents the embodiment of that concept  Multiple objects can be created from the same class Instructor: Lavi Gupta 09803266066

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Character Strings Variables and Assignment Primitive Data Types Expressions Data Conversion Interactive Programs Graphics Applets Drawing Shapes Instructor: Lavi Gupta 09803266066

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 A string of characters can be represented as a string literal by putting double quotes around the text:  Examples: "This is a string literal." "123 Main Street" "X"  Every character string is an object in Java defned by the String class  Every string literal represents a String object Instructor: Lavi Gupta 09803266066

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 In the Lincoln program from Chapter 1 we invoked the println method to print a character string  The System.out object represents a destination the monitor screen to which we can send output System.out.println "Whatever you are be a good one." object method name information provided to the method parameters Instructor: Lavi Gupta 09803266066

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 The System.out object provides another service as well  The print method is similar to the println method except that it does not advance to the next line  Therefore anything printed after a print statement will appear on the same line Instructor: Lavi Gupta 09803266066

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public class Countdown //----------------------------------------------------------------- // Prints two lines of output representing a rocket countdown. //----------------------------------------------------------------- public static void main String args System.out.print "Three... " System.out.print "T wo... " System.out.print "One... " System.out.print "Zero... " System.out.println "Liftof" // appears on frst output line System.out.println "Houston we have a problem." Instructor: Lavi Gupta 09803266066

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 The string concatenation operator + is used to append one string to the end of another "Peanut butter " + "and jelly"  It can also be used to append a number to a string  A string literal cannot be broken across two lines in a program Instructor: Lavi Gupta 09803266066

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public class Facts public static void main String args // Strings can be concatenated into one long string System.out.println "We present the following facts for your " + "extracurricular edifcation:" System.out.println // A string can contain numeric digits System.out.println "Letters in the Hawaiian alphabet: 12" // A numeric value can be concatenated to a string System.out.println "Dialing code for Antarctica: " + 672 System.out.println "Year in which Leonardo da Vinci invented " + "the parachute: " + 1515 System.out.println "Speed of ketchup: " + 40 + " km per year" Instructor: Lavi Gupta 09803266066

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 The + operator is also used for arithmetic addition  The function that it performs depends on the type of the information on which it operates  If both operands are strings or if one is a string and one is a number it performs string concatenation  If both operands are numeric it adds them  The + operator is evaluated left to right but parentheses can be used to force the order Instructor: Lavi Gupta 09803266066

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public class Addition //----------------------------------------------------------------- // Concatenates and adds two numbers and prints the results. //----------------------------------------------------------------- public static void main String args System.out.println "24 and 45 concatenated: " + 24 + 45 System.out.println "24 and 45 added: " + 24 + 45 Instructor: Lavi Gupta 09803266066

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 What if we wanted to print a the quote character  The following line would confuse the compiler because it would interpret the second quote as the end of the string System.out.println "I said "Hello" to you."  An escape sequence is a series of characters that represents a special character  An escape sequence begins with a backslash character \ System.out.println "I said \"Hello\" to you." Instructor: Lavi Gupta 09803266066

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 Some Java escape sequences: Escape Sequence \b \t \n \r \" \ \\ Meaning backspace tab newline carriage return double quote single quote backslash Instructor: Lavi Gupta 09803266066

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public class Roses //----------------------------------------------------------------- // Prints a poem of sorts on multiple lines. //----------------------------------------------------------------- public static void main String args System.out.println "Roses are red\n\tViolets are blue\n" + "Sugar is sweet\n\tBut I have \"commitment issues\"\n\t" + "So Id rather just be friends\n\tAt this point in our " + "relationship." Instructor: Lavi Gupta 09803266066

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Character Strings Variables and Assignment Primitive Data Types Expressions Data Conversion Interactive Programs Graphics Applets Drawing Shapes Instructor: Lavi Gupta 09803266066

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 A variable is a name for a location in memory  A variable must be declared by specifying the variables name and the type of information that it will hold int total int count temp result Multiple variables can be created in one declaration data type variable name Instructor: Lavi Gupta 09803266066

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 A variable can be given an initial value in the declaration • When a variable is referenced in a program its current value is used int sum 0 int base 32 max 149 Instructor: Lavi Gupta 09803266066

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public class PianoKeys //----------------------------------------------------------------- // Prints the number of keys on a piano. //----------------------------------------------------------------- public static void main String args int keys 88 System.out.println "A piano has " + keys + " keys." Instructor: Lavi Gupta 09803266066

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 An assignment statement changes the value of a variable  The assignment operator is the sign total 55 • The value that was in total is overwritten • You can only assign a value to a variable that is consistent with the variables declared type • The expression on the right is evaluated and the result is stored in the variable on the left Instructor: Lavi Gupta 09803266066

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public class Geometry public static void main String args int sides 7 // declaration with initialization System.out.println "A heptagon has " + sides + " sides." sides 10 // assignment statement System.out.println "A decagon has " + sides + " sides." sides 12 System.out.println "A dodecagon has " + sides + " sides." Instructor: Lavi Gupta 09803266066

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 A constant is an identifer that is similar to a variable except that it holds the same value during its entire existence  As the name implies it is constant not variable  The compiler will issue an error if you try to change the value of a constant  In Java we use the final modifer to declare a constant final int MIN_HEIGHT 69 Instructor: Lavi Gupta 09803266066

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 Constants are useful for three important reasons  First they give meaning to otherwise unclear literal values ◦ For example MAX_LOAD means more than the literal 250  Second they facilitate program maintenance ◦ If a constant is used in multiple places its value need only be updated in one place  Third they formally establish that a value should not change avoiding inadvertent errors by other programmers Instructor: Lavi Gupta 09803266066

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For online classes contact: 9803266066 Skype: lavigupta18 Email: techlavigmail.com Instructor: Lavi Gupta 09803266066

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