UBJSTRAINING

8/8/2019 UBJSTRAINING

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Saturday, 11 September 2010

Java Training

A pdf file composed by Uddalak Banerjee ,Emp Id -60527 ,Grade

A0,Date of joining-5th

aug,2010 based on Java-training at Birlasoft

conducted by Mr Abhishek Shahi .


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CONTENTS

1.Software Requirements

2.Steps to Install Eclipse

3.How to open a project file

4.How to configure build path

5.Sample Java program.

6.Access Modifiers

7.Methods

8.Compilation and Exception Handling using try-catch-finally.

9.Polymorphism concepts

10 Abstract Classes and interfaces

11 Inheritance

12 Composition

13.How to Debug a file in Eclipse.


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13.Control Statements

14.Wrapper Classes

15.Creating new Exceptions

16.Static blocks,anonymous classes.

17.File handling.

18.Collection(ArrayList,LinkedList,HashMap)

19.Nested Classes

20 Tomcat Server installation and working

21.How to create .War file

22.How to create Servlet


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1.Software Requirements

Softwares to install:

1.eclipse-jee-galileo-SR2-win32

2.jdk-6u3-windows-i586-p

3.apache tomcat 6.0.20.zip

2.Steps To Install Eclipse

Step 1. Cut Eclipse-jee-galileo-SR2-win32 and paste in host folder

Step 2. Install jdk-6u3

Step 3.Create shortcut on desktop

Note:Preferred Setting of workspace based on disk space

availability can be done by manually fixing the path at the time of

installation.

3.HOW TO OPEN A PROJECT FILE


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Opening a Project File

Step 1:

File/New/Other/Java/JavaProject/Next/ProjectName(java training)


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Jre is set to Use execution JRE(default)/

Step 2:

PRESS Next button and set path for src files(Eg javatraining/src)

And class files (Eg: javatraining/bin)

Step 3:


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Libraries/jreSystemLibrary[javaSE 1.6]

/Addjar(If libraries are available in own project)

PRESS FINISH AND YES

4.How to configure build path

Setting of build path:


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RightClick Project/Buildpath/Configure buildpaths/Source.

Add Library/JreSystemLibrary

Java Uses Optimisation

Create a file

Src/New/File/Filename

Note:Name Start with Capital Letter


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FILE STRUCTURE studied so far:

For any project we have a project name and followed by two

folders one is source and the other bin.Source folder contains

Java source files and bin contains class files generated by the

compiler on compilation of the source files.

A SAMPLE JAVA program:


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The output of the above code comes out to be:

Right Click/RunAs/java application


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Debugging a java file/project

Keys that are used for debugging are :

F5----------used to get into the code

F6----------Debugging-executing each statement and moving to the

next

F3---------Open declaration

Alt+left----Go back at debugging time.

To open the debugging perspective right click on the code and

select java application.

First creating a java application uddalak3.java which contains a

display method , a constructor and a main method under the class

named uddalak3.


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Now while debugging the code we first open the debug perspective

which looks as follows:

The dots which are clearly evident are the break points.

Use of f3 key gives the following scenario:

Suppose we press f3 on the uddalak3.display() method we get the

to the display method definition with the name display()

highlighted.


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OOPS(Object Oriented Programming Structure)

Three basic concepts of polymorphism were 1.encapsulation

2.inheritance and 3.polymorphism.

Use of inheritance is to enhance reusability of code.

Use of abstraction is data hiding.

Use of polymorphism is for data security(over riding) and flexibility

in code usage based on need(over loading)

Properties of Class/Object

1.Filename ------------Mandatory

2.Access Modifier-----Mandatory

3.Package

4.Methods


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5.Classname------------Mandatory

Important

1.There can be multiple classes in a program but one of themhas to be of same name as file name(It should be public)

2.Whatever class has main method the file should be of thesame name (as the class containing main())

3.There could not be more than one public class in the file.CHECK POINTS:

Q1.If 2 classes without access modifier is used what will happen?

Ans:It would produce an error.

Defination of Methods:

Methodname( parameters)

Example:

Public void main (String args[])

Access Modifiers

1.Public(Anyone can access)

2.Private(Only by you)

3.Protected(Somehow associated to you to access your data)

4.Default(Concept of package)

*Default cannot be accessed outside the host folder

#In Methods there is no concept called Default.


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#Without Object incase of main jvm creates an object.

COMPILATION

Javac

Options

-D----- destination of class file to be specified at command prompt.

EXECUTION

Java *.class

JAVA VIRTUAL MACHINE

1.JVM(Java Virtual Machine)

2.JRE(Group of class files required to execute a program)

3.API(Application Programming Interface)

#States the a program is to be written.It is collection of jar files.

a.Library

b.Jar(java archive) It is a zip file

c.package

JVM is an O.S on top of another O.S


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Properties of final keyword:::

1.FINAL cannot be inherited .

2.Final method cannot be overridden.

3.But final can be called by some other method.

Final variables are constants.Constants------------1.static and 2.final

CHECK POINT:

IF A VARIABLE IS DECLARED FINAL THEN WILL IT BE AUTOMATICALLY

STATIC?

HERE


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HER

HERE,FATHER IS THE PARENT/BASE CLASS

SON1,SON2 ARE THE CHILD/DERIVED

Keywords needed are:1. implements and 2.extends

Example:-Class father{

Public House;

Protected V1;

}

Class Son1 extends Father {

}

-Son1 can access protected variable V1.


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Cases:

Son 1 extends Father is Right

Son 2 extends Father is Right

Cases:

Son1 extends Father is wrongSon 2 extends Son1 is wrong

OverloadingIt is the process of using the same function name with variable number

of parameters .


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Polymorphism involves two basic concepts:

1.Overriding+Overloading

2.Static +Runtime Binding

Interfaces

Properties of interfaces are as follows:

1.Variables are static and final

2.public

3.METHODS without implementation


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Key points:

1.Interfaces extend other interfaces

2.classes extend classes


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3.classes implement one or more interfaces at the same time but

extend only one class at a time.

Examples:

Binding1.static [ Example: child1 objclass1= new child1();]

2.runtime[ Example: objclass1=objParent;]

Compositions

-Without extending ,inheriting direct use.

-protected members cannot be used.

#Interface to be created in separate file

Marker Interfaces

THESE interfaces have no body.

Eg : public interface Root{

}

Comments


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Calculate()in calculator class.

Use Extends

Try Debugging

Note ErrorSolution to the above assignment as executed by uddalak banerjee

,Employee id=60527 ,grade =A0 ,date of joining 5th

aug ,2010 is as

follows:


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OUTPUT DISPLAYED:

//18.08.2010

Control Statements

1 .if else


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2 switch

3.while

4. do while

5 for

Syntax of the above control statements is demonstrated as below:

For each statements

These are statements used for handling arrays.

Eg:

for(int a:arr)

{

System.out.println(a);}

Operators:

Unary: Eg ++,--

Binary:Eg +,-,*,\


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Ternary:?

ABSTRACT

abstract class a{

public int sum(int a,int b);}

Properties of abstact classes:

1.In interfaces all methods are abstract

2.All extending classes of abstract classes must give body to all the

abstract methods

3.We may not have abstract methods in an abstract class hence we

use abstract classes when we already have interfaces.

HOW TO UNDERSTAND WHETHER TO USE AN INTERFACE OR AN

ABSTRACT CLASSES


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Suppose we need to implement the above scenario of automobile

industry in java.In that case we define car as an interface.The

reason behind using car as an interface is that car contains a few

basic things like 4 wheels ,an engine,popularshaft(for power

transmission),chasse etc.Now, while Maruti ,Ford and Hyundai all

build cars of different engine capacity and with different chassedesign and popular shaft sizes and shapes each of these

companies(classes) essentially implement the basic features like 4

wheels ,engine,popularshaft,chasse etc.So we define the contracts

in the interface which essentially contains the basic ingrediants

which are later given body by the sub classes which implement the

interface(car).

Data TypesInt

Float

Double

Char

Long


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Boolean

Byte

String

Wrapper ClassesData Transfer takes place as objects only.

Uses of Wrapper classes

1.Wrapper Classes are used in case of type casting

2.Provides objects necessary for data transfer.

Use:

int INUM=10;

Integer iobj=Integer.parseInt(INUM);

All Datatypes have wrapper classes.

Long.intValue()----converts it into integer value.

Autoboxing

It was used to reduce overhead involved in type conversion.


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[Available in java 5]

All exceptions created from runtime exceptions are unchecked

exceptions.


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TRY-CATCH

For SQL code SQLexception must be caught.

Something to muse over:

Q.Can Main method be used as a part of abstract class?

Q.Can Main method be used in another class than abstract class when it is

already declared public?

Class Example:

Abstract public class AbstractTest{

Public int sum(int a ,int b){}

Abstract public float calcInterest(int p,int r,int t);

}

19.08.2010


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Q.identify errors :

Abstract class A{

Public sum(int a ,Integer b)

{

Float f=a+b;

System.out.println(f);

}

}

Ans:

Abstract class A{

Public void sum(int a ,Integer b)

{

Float f=a+b;

System.out.println(f);

}

}

Creating Exceptions of your own

public class MyException extends Exception{

My Exception(String S){

Super (s);/*calls constructor of base class

}

Assignment no 2


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Q1. Create static block example.

Q2.Create new exception.

Q3.Try implementing

Integer i=null;

Integer j=10;

System.out.println(i+j);

Q4.Try implementing constructor calling based on following:

Q5.Implement the following code and note the error:

Public class A{

Public void int1(int a,Integer b)

Float f=a+b;

System.out.Println(f);

}

Q6. Create an exception try passing a String


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Q7.Try Finally without catch in a try block

Q8.Try File Reader example.

Solution to the assignment is as follows:(as implemented by me UDDALAK

BANERJEE EMP NO 60527)


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PACKAGES:


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Throws

Catch(IOException e){

Throw newMyexception(Hello);

/*creates new instance of our MyException class*/

}

Throw blocks are written within catch block.

For every new Exception there has to be a try catch block .

Public int sum(int a,int b){

Return a+b;

}

Public int div(int a,int b) throws Exception

{

Return a/b;/*can throw exception so it has to be accompanied by a try catch

exception*/


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}

*Throws keyword is used to delegate responsibility of catching the

exception to calling code.

*A TRY BLOCK CAN HAVE MULTIPLE CATCH BLOCKS .

HIERARCHY IS LOWEST TO UPPER (Eg.we start with the lowest exception like

divide by zero exception then follow it up with its bigger parent exception

Arithmetic Exception and Then Exception .)

FINALLY

Syntax:

Try{

}

Catch(Exception e)

{

}

finally(){


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/*this block is always executed irrespective of whether catch exceptions

match or not*/

Garbage collection

By initialising Null we make an object eligible for garbage collection.

Finalize{

// called when object is ready for garbage collection

//it may or may not run immediately.

}

Use(finally)

1. To release handle after usage(Deadlock prevention)2. Operations which must be executed always.

IO

Standard Outputs:

Console

Printer device

File

Database

StandardInputs:

mouse

keyboard

scanner

**Object is foremost parent of any class in Java

//20.08.2010

Nested Classes

Public Outerclass{

Class SuperClass{

}

}


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Incase of methods if a class is created within a method then the scope

of the class is limited to that method.

Class Outerclass{

Class Superclass{

}

Static class Test{

Int i;}}

Way to access

System.out.println(Outerclass.Test.i);

Anonymous Inner Class

Anonymous class scope is in method itself.

It is not mandatory to create interface to use anonymous classes.We

can create base classes and extend it so as to use anonymous classes.


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List1.ArrayList

2.LinkedList

3.Vector

Map


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1.HashMap

2.HashTable

Advantages of Linked List

1.Random memory allocation can be done by Linked List2. Modification is fast

DisAdvantages(LinkedList)

1.Traversal is slow

Synchronized method

One process can access a resource then simultaneously another

process cannot access the same resource.

Note:Synchronized method should be small block of code

Synchronize{ }

Points to note:

#HashTable is synchronized but HashMap is not.

#In a Map of values are stored in the form of ArrayList then one key

value may point to multiple values.

#Vectors are no more used .Preferably ArrayList and LinkedLists are

used.

Assignments :

1. Create List of 10 valuesRemove 5

thelement and 8

thelement

Add new value 5th

and change 10th

element

2.Try Employee Example

3.Create a class which has certain parameters:

Int day;----------------------------------------display Topics(day);

String Training Name;----------------------display Training(day);

List Topics;-------------------------------------add Training(); removeTraining();


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The answers to the assignment as executed by uddalak banerjee

empid=60527 ,grade=a0,date of joining =5th

aug, 2010

Ans 1:

Ans 2:


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Ans 3:


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TOMCAT CONFIG

Bin/startup.bat/CreateShortcut

Now go to Start>Run>cmd


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And then repeat the following steps (in the present case tomcat 6 has

been installed in d drive within ubj folder .SO accordingly the path is

traced as follows:

Set Path

Once we had tried out all the steps we find the error message as

displayed.Neither the JAVA_HOME .....(as displayed).

Rightclick on Mycomputer and go to System properties tab


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Click on environment variables\Add new Variable\JAVA_HOME

Set the path of jdk as installed in the computer there as value.

In this case the path of jdk installed in my computer was ---

C:\Program Files\Java\jdk1.6.0_03


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WEB APPLICATION STRUCTURE:


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STEPS REQUIRED TO CREATE WEB PROJECTS

File\New\Other\Web\Dynamic Web Project\Proj Name

HOW TO CREATE WAR FILE:

WHICH IN THIS CASE IS TRAININGAPPLICATION and a default tag which indicates the execution of which part of the code

The projectname.war file is to be created.Base directory indicates the directory wherethe project is present .Similarly all the subdirectories necessary for the execution for the

project are provided with corresponding paths in the form of tag.=======================================================================

-->

-


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activity that is performed during creation of a .war file is that all previous instances ofbuild and dist directories for the project is deleted.

-- >

-

- - -

-

-

-

-

-


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===================================================================

-->

--

-

-

-

-

-

-


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SERVLET

Servlet is used to trigger different classes.Jsp is used to mainly to

create View/Presentation Layer.

METHODS OF SIGNIFICANCE WHILE IMPLEMENTING A SERVLET:

SendErrordoPut

doDelete

forward

include

sendRedirect

Other important topics to be covered are

printContent

Contenttype

Creation of a web project is demonstrated as below:

Step 1:

First a project is created by File/new/Others/Dynamic Web Project.

Step 2:


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Then a project name is given to the project which in our instance is

uddalakweb

Press NEXT

Step 3:

Select the default output folder as build1\classes.Press Finish.

Step 4:

Create a folder named classes under the WebContent\WEB_INF.

Step 5:

Create folders named build and dist under the uddalakweb

project.

Note:build and dist folders are created for the purpose of .war file

creation.


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Step 6:

Create a Jsp folder under the WebContent folder.

Note:This folder is used to store the jsp files.

Step 7:

Create a servlet by src/CreateServlet/package/Servlet


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The new servlet looks like:

Step 8:


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Copy servlet-api.jar from tomcat6/lib folder and paste it in

WEB_INF/lib

Step 9:

Make the build.xml file as already prescribed in .war creation.Deploy it

using ant build.


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Step 10:

Execute the application and use web browser to access the servlet.

NOTE:Everytime on producing any change in the application .Build theapplication again and remove the old .war file manually .

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