Notepad Using Java

8/10/2019 Notepad Using Java

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JAVAUsing NOTEPAD

Submitted by:

Lavish Bansal

Submitted to:

Mr Amit Monga


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HISTORY OF C,C++ AND JAVA

C

1969-1973

Denis Ritche

A T & T Bell Lab

Windows

C++1975-1984

Bjarne

StrausStrupWindows

JAVA1991-1995

James Gosling

Sun MicrosystemsOracle


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FEATURES OF OOPS

It has 4 main features:-

>Inheritance

>Encapsulation>Polymorphism

>Abstraction


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What is JAVA?

A general purpose object-oriented Programing

language.

Write Once Run Anywhere (WORA).

Designed for easy web/internet applications

Widespread acceptance

It is case sensitive language. It is developed and deployed.


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Why JAVAimportant ?

Two reasons :

Trouble with C/C++ language is that they are

not portable and are not platform

independent languages.

Emergence of World Wide Web, which

demanded portable programs

Portability and security necessitated the

invention of Java.


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New features added in Java

Multithreading, that allows two or more pieces ofthe same program to execute concurrently.

C++ has a set of library functions that use acommon header file. But java replaces it with itsown set of APIclasses.

It adds packagesand interfaces.

Java supports automatic garbage collection.

Break and continue statements have beenenhanced in java to accept labels as targets.

The use of unicode characters ensures portability.


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Features that differ:

Though C++ andjavasupports Boolean data type,

C++ takes any nonzerovalue as true and zero as

false. True and false in java are predefined literals

that are values for a boolean expression.

Java has replaced the destructor function with a

finalize() function.

C++ supports exception handling that is similar tojava's. However, in C++ there is no requirement

that a thrown exception be caught.


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DATATYPE

Basically Data type is which type of value store

in variable.

SYNTAX ;

Int age;

It is of 2 types:

Primitive(Pre defined) and Reference(Userdefined).


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ARRAYS

Array is a collection of variables of same

datatype.

SYNTAX [] = new

[];

Example:- int [] arr=new int [5];


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PACKAGES

Packages are collection of classes or it act as a

container for different classes.

How to create a package?

PACKAGE ;

class abc

{};


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CONSTRUCTOR

Class name and constructor name must be same.

It do not have any return type.

It is called when we create object of class.

It is used to initialise and store the variable.

Class hh

{

int a;

hh(){a=10;

}


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INHERITANCE

It is basically reusability ,like parent->child ,

super class->sub class.

SYNTAX :- extends

Type of inheritance:-

>single

>multilevel>multiple


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Overriding & overloading

Overriding is function name and function

signature should be same.

Overlaoding is function name is same and

function signature is different.


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SUPER KEYWORD AND SUPER

METHOD

A subclass method can invoke a superclass

method using the super keyword.

Super method is used for invoking parent

parameter constuctor.

Example:-

l


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class person

{

String firstname;

String lastname;

person(String fname,String lname)

{firstname=fname;lastname=lname;

}

void display()

{System.out.println("person:");

System.out.println("firstname:"+firstname);

System.out.println("lastname:"+lastname);}

}

class student extends person

{

int id;

String standard;String instructor;

student(String fname,String lname,int nld,String stnd,String instr)

{

super(fname,lname);

id=nld;standard=stnd;


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instructor=instr;

}

void display()

{

System.out.println("student:");super.display();

System.out.println("id:"+id);

System.out.println("standard:"+standard);

System.out.println("instructor:"+instructor);

}

}class teacher extends person

{

String mainsubject;

String type;

int salary;

teacher(String fname,String lname,String sub,int slry,String stype)

{

super(fname,lname);

mainsubject=sub;

salary=slry;


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type=stype;

}

void display()

{

System.out.println("teacher:");

super.display();

System.out.println("mainsubject:"+mainsubject);

System.out.println("salary:"+salary);

System.out.println("type:"+type);

}

}

class inheritancedemo

{

public static void main(String arr[])

{

person pobj=new person("rayan","miller");student sobj=new student("jacob","smith",1,"1-b","roma");

teacher tobj=new teacher("daniel","mart","english",6000,"primary teacher");

pobj.display();

sobj.display();

tobj.display();}}


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ABSTRACT CLASS

Abstract is a keyword used along with classes

and methods.

In this we only declare the methods , we

define these methods in there child class.

Abstract class use only abstract methods.

Example:-


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Abstract class dd

{

public abstract void a();

public abstract void b();

}

class s extends dd

{

public void a()

{

int a=10;

System.out.println(a);

}public void b()

{int bb=10;

System.out.println(bb);

public static void main(String arr[])

{

s.b=new s();

b.a();b.bb();

}}


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INTERFACE

It is used for multiple inheritance.

In interface we only declare the methods , we definethese methods in there child class.

Example:-

Interface kk{

}

Interface gg

{

}

Class s implements kk,gg


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EXCEPTION HANDLING

Basically we have 3 types of errors:-

>Syntax error- occurs at compilation time

>Logical error- can occur at compile time or run

time>Runtime error- basically unexpected

So to resolve this we use exception handling.

It has 3 blocks:-

> Try used where exception can occur.> Catchused to handle the exception.

>Finallyalways run.


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EXAMPLE OF EXCEPTION HANDLING class ex

{ public static void main(String[]arr)

{

try

{

String aa=arr[0]; int a=Integer.parseInt(arr[1]);

int b=Integer.parseInt(arr[2]);

int c=a/b;

System.out.println(c);

System.out.println(aa);

System.out.println(b);

}

catch(Exception e)

{

System.out.println(e);

}


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USER DEFINED EXCEPTION

It is when the user defined his/her definesthere own exception.

It uses 2 keywords throw and throws.

Throws clause is used to declare an exceptionand throw keyword is used to throw anexception explicitly.

The keyword throw is used inside methodbodyand throws clause is used in methoddeclaration.


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G U I

Defined as graphical user interface.

Till now we had used it on black command

window but from now we will se how it will

work and we will visualise it .

Example:- import java. Awt.*;

Awt=abstract window toolkit

The child class of awt is swingx

Example:-import javax.swing.*;


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CONSTRUCTION OF FRAME

Import javax.swing.*;

Class cont

{

Jframe f;

Jbutton b;

cont()

{

f=new Jframe (welcome);

b=new Jbutton(submit);

}

Public void aa()

{f.add(b);

f.setSize(100,100);

f.setvisible(true);

Public static void main(String arrr[])

{cont v=new cont();

v.aa();}}


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Thank You

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Notepad Using Java