ex. no :1 print the digits of a number · examkey.wordpress.com 25245 - java programming lab 1 aim...

examkey.wordpress.com 25245 - JAVA PROGRAMMING LAB

1

Aim :

To write a java program to print the individual digits of a 3 digit number.

Algorithm:

1. Get any 3 digit integer as input

2. Find the last digit by n%10 and store it in r;

3. Print value of r

4. Reduce n by n/10;

5. Repeat this until n not equal to 0

Program:

/* Program to print the individual digits of a 3-digit number */

import java.io.*;

class SumDigit

{

public static void main(String args[])throws IOException

{

BufferedReader din=new BufferedReader(new

InputStreamReader(System.in));

int n;

System.out.print("Enter the number:");

n=Integer.parseInt(din.readLine());

System.out.println("The digits in the number are”);

while(n!=0)

{

int r=n%10; /* Find the last digit */

n=n/10; /* Reduce the number */

System.out.println(r);

}

}

}

Ex. No :1 Print the digits of a number


2

Output:

D:\java>javac Digits.java

D:\java>java Digits 729

The number is 729

The digits in the number are

**************************

9

2

7

D:\java>

Viva Questions:

What are command line arguments?

The values that are passed to the main method from the command line while executing

the program are called as command line arguments.

What are the various types of operators available in java?

Arithmetic operator, Relational operator, Logical operator, Bitwise operator,Increment

and decrement operator, Assignment operator, Conditional operator and Special operator.

What is a ternary operator?

The operator that takes three arguments is called as ternary operator. The conditional

operator is the only ternary operator available in java.

What is the use of Integer.parseInt() method?

This method is used to convert the String object into integer value.

What is called as a Boolean expression?

An expression that returns either true or false value is called a Boolean expression.


3

Aim:

To write a java program to read two integers and print the larger number followed by the

words “is larger”. If the numbers are equal print the message “These numbers are equal”.

Agorithm:

1. Import the package java.io*

2. Read the value in the variable a and b

3. check whether a>b if it is true print a is larger

4. else check b>a if it is true print b is larger

5. else print a is equal to b

Program:

import java.io.*;

class Large

{


{



int a,b;

System.out.print("Enter the value of a:");

a=Integer.parseInt(din.readLine());

System.out.print("Enter the value of b:");

b=Integer.parseInt(din.readLine());

System.out.println("a="+a+"\t\tb="+b);

if(a==b)

System.out.println("These numbers are equal");

else if(a>b)

System.out.println(a+ " is larger");

Ex. No :2 Biggest Number


4

else

System.out.println(b+" is larger");

}

}

Output 1:

D:\java>javac Large.java

D:\java>java Large

Enter the value of a:45

Enter the value of b:34

a=45 b=34

45 is larger

Viva Questions:

What is a control structure?

Control structures are statements that are used to change the flow of the program based

on some condition.

What are the two types of control structures?

Decision making statements and Looping statements

What are decision making statements?

The statements that are used to execute only a block of code and leaving others based on

the condition.

What are the various decision making statements available in java?

Simple if, if..else, nested if..else, else if ladder and switch statement.


5

Aim:

To write a java program to print the Armstrong numbers. (153 = 13 + 5

3 + 3

3 = 1 + 125

+27 =153 is an Armstrong number)

Algorithm:


2. Initialize sum=0

3. Find n%10 and store it in variable s and add with sum.

4. Repeat the above step till n!=0, Print Sum

Program:

import java.io.*;

class Armstrong

{


{

System.out.println("Armstrong numbers");

System.out.println("*****************");

for(int i=100;i<=999;i++)

{

int n=i,sum=0;

while(n!=0)

{

int r=n%10;

sum=sum+(int)Math.pow(r,3);

n=n/10;

}

if(sum==i)

System.out.println(i);

Ex. No :3 Armstrong Nnumber


6

}

}

}

Output:

D:\java>javac Armstrong.java

D:\java>java Armstrong

Armstrong numbers

*****************

153

370

371

407

Viva Question:

What is the use looping statement?

The looping statement is used to execute a block of repeatedly until the condition is true.

What are the various looping statements available in java?

While, do.. while and for statements.

What is the difference between while and do..while?

In case of while statement the block of code will not be executed atleast once if

the condition is false at the first run.

In case of do..while statement the block of code will be executed atleast once if

the condition is false at the first run.


7

Aim:

To write a java program to find the largest and smallest number in an array.

Algorithm:


2. Declare an array variable member

3. Initialize variable big =0,small=0

4. And check each element in array with big and also with small element

5. After finding biggest and smallest element in array. Print the element

Program:

import java.io.*;

class ArrBig

{ public static void main(String args[])throws IOException

{

int a[]=new int[20];

int n,big,small;



System.out.print("Enter number of terms in the array:");

n=Integer.parseInt(din.readLine());

System.out.println("Enter array element:");

for(int i=0;i<n;i++)

{ System.out.print("a["+i+"]:");

a[i]=Integer.parseInt(din.readLine());

}

big=a[0]; small=a[0];


{

if(a[i]>big)

big=a[i];

if(a[i]<small)

Ex. No :4 Largest and Smallest in the array


8

small=a[i];

}

System.out.println("\nThe elements in the array");


System.out.print("\t"+a[i]);

System.out.println("\nThe biggest element in the array is "+big);

System.out.println("The smallest element in the array is "+small);

}

}

Output:

D:\java>javac ArrBig.java

D:\java>java ArrBig

Enter number of terms in the array:5

Enter array element:

a[0]:56

a[1]:78

a[2]:12

a[3]:4

a[4]:89

The elements in the array

56 78 12 4 89

The biggest element in the array is 89

The smallest element in the array is 4

Viva Questions:

Define array-An array is a collection of elements of same data type referred by a common

name. The elements are of the array are stored in consecutive memory locatons.

Types of arrays-One dimensional array, two dimensional array and multidimensional arrays.

How to declare a two dimensional array?

Datatype arrayname[][]=new datatype[ row size][column size]

How the individual elements of an array can be accessed?


9

The individual elements can be accessed using the index. The index of the first element

starts with 0.

Aim:

To write a java program that creates a string object and initializes it with your

name and performs the following operations

a) To find the length of the string object using appropriate String method.

b) To find whether the character ‘a’ is present in the string. If yes find the

number of times ‘a’ appear in the name and the location where it appears

Algorithm:

1. Initialize the string object

2. Find the length of the string

3. Find the number of occurrence of character ‘a’

4. Print the location of the occurence

Program:

class StringDemo

{

public static void main(String args[])

{

String name="Java Programming";

int count=0;

System.out.println("The given name is "+name);

System.out.println("The length of name is "+name.length());

if(name.indexOf('a')<0)

System.out.println("The character 'a' is not present in my name");

else

{

System.out.println("The character 'a' is present in the locations");

int loc=0;

while(loc<name.lastIndexOf('a'))

Ex.No.5 String


10

{

int x=name.indexOf('a',loc);

System.out.println(x);

loc=x+1;

count++;

}

System.out.println("The character 'a' is present "+count+" times");

}

}

}

Output:

D:\java>javac StringDemo.java

D:\java>java StringDemo

The given name is Java Programming

The length of name is16

The character 'a' is present in the locations

1

3

10

The character 'a' is present 3 times

D:\java>


11

Aim:

To write a java program to display total marks of 5 students using student class. Given

the following attributes: Regno(int), Name(string), Marks in subjects(Integer Array), Total (int).

Algorithm:

1. Initialize 5 student register no,name and marks of 3 subjects

2. Find the total marks of each student

3. Print the register no,name and marks and total of 5 students

Program:

import java.io.*;

/* Student class */

class Student

{

int regno,total;

String name;

int mark[]=new int[3];

void readinput() throws IOException

{



System.out.print("\nEnter the Reg.No: ");

regno=Integer.parseInt(din.readLine());

System.out.print("Enter the Name: ");

name=din.readLine();

System.out.print("Enter the Mark1: ");

mark[0]=Integer.parseInt(din.readLine());



Ex. No :6 Classes and Objects (Students Mark Sheet)


12



total=mark[0]+mark[1]+mark[2];

}

void display()

{

System.out.println(regno+"\t"+name+"\t"+mark[0]+"\t"+mark[1]+"\t"+ma

rk[2]+"\t"+total);

}

}

/* Main class */

class Mark

{

public static void main(String args[]) throws IOException

{

Student s[]=new Student[5];

for(int i=0;i<5;i++)

{

s[i]=new Student();

s[i].readinput();

}

System.out.println("\t\t\tMark List");

System.out.println("\t\t\t*********");

System.out.println("RegNo\tName\tMark1\tMark2\tMark3\tTotal");


s[i].display();

}

}

Output:

D:\java>javac Mark.java

D:\java>java Mark


13

Enter the Reg.No: 1

Enter the Name: Balu

Enter the Mark1: 67

Enter the Mark2: 90

Enter the Mark3: 56

Enter the Reg.No: 2

Enter the Name: Geetha

Enter the Mark1: 87

Enter the Mark2: 79

Enter the Mark3: 92

Enter the Reg.No: 3

Enter the Name: Vimal

Enter the Mark1: 87

Enter the Mark2: 60

Enter the Mark3: 71

Enter the Reg.No: 4

Enter the Name: Fancy

Enter the Mark1: 92

Enter the Mark2: 89

Enter the Mark3: 86

Enter the Reg.No: 5

Enter the Name: Janani

Enter the Mark1: 78

Enter the Mark2: 90

Enter the Mark3: 91

Mark List

*********

RegNo Name Mark1 Mark2 Mark3 Total

1 Balu 67 90 56 213

2 Geetha 87 79 92 258

3 Vimal 87 60 71 218


14

4 Fancy 92 89 86 267

5 Janani 78 90 91 259

Aim :

To write a java program to show how a class implements two interfaces.

Algorithm:

1. Create two interface A and B

2. Implement the two interface in the myclass

3. Create an object for myclass amd access the interface methods

Program:

/* Program to show a implementing two interfaces */

/* First interface */

interface One

{

int x=12;

}

/* Second interface */

interface Two

{

int y=10;

void display();

}

/* Class implementing the interfaces */

class Demo implements One,Two

{

public void display()

{

System.out.println("X in inteface One ="+x);

System.out.println("Y in interface Two="+y);

System.out.println("X+Y= "+(x+y));

}

Ex. No :7 Interfaces(Class implementing two interfaces)


15

}

/* Main class */

class TwoInterface

{


{

Demo d=new Demo();

d.display();

}

}

Output:

D:\java>javac TwoInterface.java

D:\java>java TwoInterface

X in inteface One =12

Y in interface Two=10

X+Y= 22

Viva Questions:

What is an interface?

Interface is just like a class which contains final variables and public abstract methods. It

is used to implement multiple inheritance in java.

What is an abstract method?

The method which has only declaration in the super class and defined in the subclass is

known as abstract method.

Syntax for defining an interface

interface interfacename

{ //define the static variables and declare abstract methods

}

How to implement interface?

The abstract methods should be implemented in a class to use the interface in our

program.

class className extends superclassname implements interface1, interface2, …


16

{ //define the members

}

Aim:

To write a java program to create our exception subclass that throws exception if the sum

of two integers is greater than 99.

Algorithm:

1. Import the package java.io.*

2. Create user defined exception class

3. In main class, one error may occur related to user defined exception

4. If the error is caught the appropriate catch block executes

Program:

/* User defined exception class */

import java.io.*;

/* User defined exception class */

class MyException extends Exception

{

MyException(String mg)

{ super(mg);

}

}

/* Main class */

class UserExcep

{


{

BufferedReader bin=new BufferedReader(new


int a,b;

System.out.print("Enter the value of A:");

a=Integer.parseInt(bin.readLine());

Ex. No :8 Exception Handling (User Defined Exception)


17

System.out.print("Enter the value of B:");

b=Integer.parseInt(bin.readLine());

try

{ int c=a+b;

if(c>99)

throw new MyException("The numbers are too big");

System.out.println(a+"+"+b+"="+c);

}

catch(MyException e)

{ System.out.println("The sum of numbers should be less than 99");

System.out.println(e.getMessage());

}

}

}

Output:

D:\java>javac UserExcep.java

D:\java>java UserExcep

Enter the value of A:56

Enter the value of B:34

56+34=90

C:\javapgm>java UserExcep

Enter the value of A:56

Enter the value of B:90

The sum of numbers should be less than 99

The numbers are too big

Viva Questions:

What is an exception?

An exception means errors that occur during execution of the program that

disrupts normal flow of the program.

What are the steps in handling exception?

The following are the tasks in handling exceptions


18

• Find the problem (Hit the exception )

• Inform that an error has occurred (Throw the exception)

• Receive the error (Catch the exception)

• Take corrective action (Handle the exception )

Explain try..catch block?

The programmers can use the try.. catch block to handle the exceptions that suit

their programs. This avoids abnormal termination of the program.

Syntax

try

{

//Statements that may generate the exception

}

catch(exceptionclass object)

{

//Statements to process the exception

}

finally()

{

//Statements to be executed before exiting exception handler

}

Try block: Inside the try block we can include the statements that may cause an exception and

throw an exception.

The catch block: The catch block contains the code that handles the exceptions and may correct

the exceptions that ensure normal execution of the program. Catching the thrown exception

object from the try block by the corresponding catch block is called throwing an exception.

What is the use of finally block?

The finally block contains codes that will be executed when the exception occurs or not.

What is the use of multiple catch blocks?

The multiple catch blocks are used when there is a possibility of more then one type of

exception gets generated when a try block is executed

What is meant by user defined exception?


19

The exception class that is defined by the user to suit their need by deriving the Exception

class is called user defined exception.

Aim:

To write a java program to create a text file using ByteStream class.

Algorithm:


2. Create a string variable and assign value

3. Create a file object by using output strea class and specify the file name to be created

as argument

4. Write the string into a file using write()

5. Then display the file using type command

Program:

/* Program to create a text file using Byte Stream class */

import java.io.*;

class FileWriteDemo

{

public static void main(String srgs[])throws Exception

{

int len,size;

String s;

FileOutputStream fout=new FileOutputStream("Sample.txt");



byte myarr[]=new byte[1024];

System.out.println("Enter the contents of the sample.txt file. Give

* in new line to end ");

while(true)

{

s=din.readLine();

Ex. No :9 Files using Byte Stream Class


20

if (s.equals("*")) break;

myarr=s.getBytes();

91

fout.write(myarr);

fout.write('\n');

}

fout.close();

System.out.println("The file is created");

}

}

Output:

D:\java>javac FileWriteDemo.java

D:\java>java FileWriteDemo

Enter the contents of the sample.txt file. Give * in new line to end

Sample file created

*

The file is created

Checking the created file

D:\java>type sample.txt

Sample file created

D:\java>


21

Aim:

To write a java program to copy one file to another.

Algorithm:


2. Initialize two strings

3. Get the source file and store it in one string

4. Copy the source file into another file

Program:

import java.io.*;

class FileCopyDemo

{

public static void main(String srgs[])

{

String infile,outfile;



try

{ System.out.print("Enter the name of the file to be copied:");

infile=din.readLine();

System.out.print("Enter the name of the new file :");

outfile=din.readLine();

FileOutputStream fout=new FileOutputStream(outfile);

FileInputStream fin=new FileInputStream(infile);

byte myarr[]=new byte[512];

while(fin.read(myarr) !=-1)

{ fout.write(myarr);

}

Ex.No :10 Files copy one file to another file)


22

System.out.println("The file "+infile+" is copied to "+outfile);

fout.close();

fin.close();

}

catch(IOException e)

{ System.out.println(e.getMessage());

}

}

}

Output:

1. D:\java>javac FileCopyDemo.java

D:\java>java FileCopyDemo

Enter the name of the file to be copied:sample.txt

Enter the name of the new file :sa.txt

The file sample.txt is copied to sa.txt

2. Verifying the copied file

Viva Question:

What is a file?

The file is a collection of information.

What are the properties specified by the File class in java?

The File class abstracts properties like size, permission, time and date of creation and

modification.

What are streams?

Streams are logical entities that re linked with data source/ destination

What are input streams and output stream?

Input streams are used to read data from a keyboard, a disk file or from memory buffer.

Output streams are used to write data to a disk file, memory buffer or display screen etc.

How are streams classified according to the type of data?

The streams are classified into byte streams and character streams based on the

type of data they read or write.

Byte streams read and write bytes.


23

Character streams read and write characters and strings.

Aim:

To write a menu based java program that accepts a shopping list of four items

from the command line and store in a Vector and perform operations

1. To add an item at a specific location in the list.

2. To delete an item in the list.

3. To print the contents of the vector.

4. To delete all elements

5. To add an item at the end of the vector

Algorithm:

1. Import the package java.io.* and java.util.

2. Receive four input from the command line and store it in the vector

3. Using Switch statement, do all vector operations

4. Perform the operation by using vector.

Program:

import java.io.*;

import java.util.*;

class DemoVector

{


{



Vector v=new Vector();

int ch;


v.addElement(args[i]);

System.out.println("\nThe items in the shopping list");

Ex. No :1 Vectors


24

System.out.println("\n**********************");

for(int i=0;i<v.size();i++)

System.out.println(v.elementAt(i));

do

{

System.out.println("\n\t\t\tMenu");

System.out.println("\t\t\t******");

System.out.println("\t\t1. To add an item at a specific

location in the list.");

System.out.println("\t\t2. To delete an item in the list.");

System.out.println("\t\t3. To print the contents of the

vector.");

System.out.println("\t\t4. To delete all elements.");

System.out.println("\t\t5. To add an item at the end of the

vector.");

System.out.println("\t\t6. Exit");

System.out.print("\n\n\tEnter your choice:");

ch=Integer.parseInt(din.readLine());

switch(ch)

{

case 1:

System.out.print("\nEnter the item to be added to the list:");

String s=din.readLine();

System.out.print("\nEnter the position to be inserted:");

int pos=Integer.parseInt(din.readLine());

v.insertElementAt(s,pos);

break;

case 2:

System.out.print("\nEnter the item to be deleted from the

list:");

s=din.readLine();


25

v.removeElement(s);

break;

case 3:

if(v.isEmpty())

System.out.println("The shopping list is empty");

else

{

System.out.println("\nThe items in the shopping

list");

System.out.println("\n**********************");

or(int i=0;i<v.size();i++)

System.out.println(v.elementAt(i));

}

break;

case 4:

v.removeAllElements();

break;

case 5:

System.out.print("\nEnter the item to be

aded to the list:");

s=din.readLine();

v.addElement(s);

break;

}

}while(ch<=5);

}

}

Output:

D:\java>javac DemoVector.java

D:\java>java DemoVector LuxSoap Rin HairOil Rice

The items in the shopping list


26

**********************

LuxSoap

Rin

HairOil

Rice

Menu

******




4. To delete all elements.

5. To add an item at the end of the vector.

6. Exit

Enter your choice:1

Enter the item to be added to the list:Dhal

Enter the position to be inserted:2

Menu

******






6. Exit

Enter your choice:3


**********************

LuxSoap

Rin

Dhal

HairOil


27

Rice

Menu

******






6. Exit

Enter your choice:5

Enter the item to be added to the list:ToothPaste

Menu

******






6. Exit

Enter your choice:3


**********************

LuxSoap

Rin

Dhal

HairOil

Rice

ToothPaste

Menu

******



28





6. Exit

Enter your choice:2

Enter the item to be deleted from the list:Rice

Menu

******






6. Exit

Enter your choice:3


**********************

LuxSoap

Rin

Dhal

HairOil

ToothPaste

Menu

******






6. Exit


29

Enter your choice:6

Viva questions:

What is Vector?

Vector is just like an array that can store elements of different data types. The elements of

the vector can only be objects. So the primitive data type must be converted into object data type

before adding to the vector.

What is the difference between capacity and size of the Vector?

Capacity specifies the maximum number of objects that can be stored in the vector. Size

specifies the number of objects that are present in the Vector.

What are the difference between array and Vector?

The elements of the array are of same data type. The elements of the Vector can be

different data type. The elements of the array can be of primary data type. The elements of the

Vector can only be objects. The capacity of the array is fixed. The size of Vector can be changed

during run time.


30

Aim :

1. To write a java program to create a StringBuffer object and illustrate how to append

characters and to display the capacity and length of the string buffer

2. Create a StringBuffer object and illustrate how to insert characters at the beginning.

3. Create a StringBuffer object and illustrate the operations of the append() and

reverse() methods.

Algorithm:

1. Initialize the string

2. Find the length of the string

3. Insert the character at the beginning

4. Reverse the string and print

Program :

Class StringBuffer

{

Public static void main(String args[])

{ StringBuffer a = new StringBuffer(“RAJ”);

System.out.println(“Length”+a.length());

System.out.println(“Capacity”+a.capacity());

String b = new String(“RAM”);

a=a.append(b);

System.out.println(a);

System.out.println(a.reverse());

}

}

OUTPUT

Length 6

Capacity 22

RAJ RAM

Ex.No.2. StringBuffer


31

C.RAJ RAM

Aim:

To write a program in java with a class Rectangle with the data fields width, length, area

and colour. The length, width and area are of double type and colour is of string type.The

methods are get_length(), get_width(), get_colour() and find_area().

Create two objects of Rectangle and compare their area and colour. If the area and colour

both are the same for the objects then display “Matching Rectangles”, otherwise display “ Non-

matching Rectangle”.

Algorithm:

1. Initialize length and breadth,color of rectangles

2. Get input for 2 rectangles from the user

3. Find matching between rectangles

4. Print the status whether it is matching or not

Program:

/* Program in Java to compare the values in two objects*/

import java.io.*;

/* Rectangle class */

class Rectangle

{

private double length,width,area;

private String colour;

BufferedReader din=new BufferedReader(new InputStreamReader(System.in));

void get_length()throws IOException

{

System.out.print("Enter the length:");

length=Double.parseDouble(din.readLine());

Ex. No :3 Classes and Objects (Matching Rectangles)


32

}

void get_width()throws IOException

{

System.out.print("Enter the width:");

width=Double.parseDouble(din.readLine());

}

void get_colour()throws IOException

{

System.out.print("Enter the colour:");

colour=din.readLine();

}

double find_area()

{

area=length*width;

return area;

}

String put_colour()

{

return colour;

}

}

/* Main class */

class MatchRect

{


{

Rectangle r1,r2;

r1=new Rectangle();

r2=new Rectangle();

System.out.println("Enter the data for Rectangle 1:");

r1.get_length();


33

r1.get_width();

r1.get_colour();

System.out.println("Enter the data for Rectangle 2:");

r2.get_length();

r2.get_width();

r2.get_colour();

String c1=r1.put_colour();

String c2=r2.put_colour();

if ((r1.find_area()==r2.find_area()) && (c1.compareTo(c2)==0))

System.out.println("\n\tMatching Rectangles");

else

System.out.println("\n\tNon-Matching Rectangles");

}

}

Output:

D:\java>javac MatchRect.java

D:\java>java MatchRect

Enter the data for Rectangle 1:

Enter the length:6

Enter the width:5

Enter the colour:Pink


Enter the length:5

Enter the width:6


Matching Rectangles

D:\java>javac MatchRect.java

D:\java>java MatchRect


Enter the length:5

Enter the width:5


34

Enter the colour:Green


Enter the length:5

Enter the width:5


Non-Matching Rectangles

Viva Questions

What is class?

A class is a collection of data and methods that defines an object. The variables and

methods (functions) of a class are called members of the class.

What is an object?

The variable of type class is called object.

Syntax for defining a class

class className

{

//Declaration of instance variables

//Constructors

//Instance Methods

}

How can we create objects?

The objects can be created using the new operator.

className objectNname=new className();

How the members of a class can be accessed?

The members of the class can be accessed using the dot operator

Objectname .variable

Or

Objectname.methodName(Arguments)


35

Aim:

To write a java program to define a class that represent Complex numbers with

constructor to enable an object of this class to be initialized when it is declared and a default

constructor when no argument is provided and define methods to do the following by passing

objects as arguments

a) Addition of two Complex numbers

b) Subtraction of two Complex numbers

c) Printing the Complex numbers in the form (a, b).

Algorithm:

1. Initialize two complex number

2. Find the sum of the two complex number

3. Find the subract of the two complex number

4. Print the complex number in form(a,b)

Program:

/* passing object as parameters */

class Complex

{

int r,i;

Complex()

{

r=i=0;

}

Complex(int a,int b)

{

r=a;

Ex. No :4 Passing Objects as Arguments


36

i=b;

}

void display( )

{

System.out.println("("+r+","+i+")");

}

Complex add(Complex c1,Complex c2)

{

Complex c3=new Complex();

c3.r=c1.r+c2.r;

c3.i=c1.i+c2.i;

return c3;

}

Complex sub(Complex c1,Complex c2)

{

Complex c3=new Complex();

c3.r=c1.r-c2.r;

c3.i=c1.i-c2.i;

return c3;

}

}

/* Main class */

class CompNum

{


{

Complex x1,x2,x3,x4;

x1=new Complex(7,5);

x2=new Complex(4,3);

x3=new Complex();

x4=new Complex();


37

x3=x1.add (x1,x2);

x4=x1.sub(x1,x2);

System.out.print("The first number :");

x1.display();

System.out.print("The second number :");

x2.display();

System.out.print("The sum :");

x3.display();

System.out.print("The difference :");

x4.display();

}

}

Output:

D:\java>javac CompNum.java

D:\java>java CompNum

The first number :(7,5)

The second number :(4,3)

The sum :(11,8)

The difference :(3,2)

Viva Questions:

What is a constructor?

Constructors are special methods whose name is same as the class name. The

constructors do not return any value.

The constructors are automatically called when an object is created. They are usually

used to initialize the member variables.

What is a default constructor?

Constructor that does not take any argument is called default constructor.

What is meant by constructor overloading?


38

Defining more than one constructor for a class which differ in the number of arguments /

type of arguments or both is called constructor overloading.

Aim:

To write a java program to create a Player class and inherit three classes Cricket_Player,

Football_Palyer and Hockey_Player.

Algorithm:


2. Create a class player as a base class

3. Inherit Cricket,football,hockey classes from the player class.

Program

/* Hierarchical Inheritance */

/* Super class */

class Player

{

String name;

Player(String n) //Constructor

{

name=n;

}

void display()

{

System.out.println("Player name:"+name);

}

}

/*Sub class 1*/

class Cricket_Player extends Player

{

String pos;

Cricket_Player(String n,String s)

{

Ex. No :5 Inheritance


39

super(n); //Calling super class constructor

pos=s;

}

void print()

{

System.out.println("\n\n\tCricket Player");

display(); //Calling super class method

System.out.println("Category :"+pos);

}

}

/* Sub class 2 */

class Football_Player extends Player

{

String pos;

Football_Player(String n,String s)

{


pos=s;

}

void print()

{

System.out.println("\n\n\tFootball Player");



}

}

/* Sub class 3 */

class Hockey_Player extends Player

{

String pos;

Hockey_Player(String n,String s)


40

{


pos=s;

}

void print()

{

System.out.println("\n\n\tHockey Player");



}

}

/* Main class */

class DemoInher

{


{

Cricket_Player c=new Cricket_Player("Kumble","Bowler");

Football_Player f=new Football_Player("Anand","Football

receiver");

Hockey_Player h=new Hockey_Player("Parzan","Defence man");

c.print();

f.print();

h.print();

}

}

Output:

D:\java>javac DemoInher.java

D:\java>java DemoInher

Cricket Player

Player name:Kumble

Category :Bowler


41

Football Player

Player name:Anand

Category :Football receiver

Hockey Player

Player name:Parzan

Category :Defence man

D:\java>

Viva Questions:

What is inheritance?

Inheritance is the process of deriving a new class from an existing class. The newly

created class is called sub class and the already existing class is called super class.

What are the types of inheritance?

Single inheritance: One super class and single sub class.

Multiple inheritance: More than one super class and single subclass.

Hierarchial inheritance: one super class and more than one subclass.

Multilevel inheritance : Deriving a sub class from another sub class

Explain multiple inheritance in java?

In java we can have only one super class for a sub class so we cannot directly implement

multiple inheritance. We use the concept of Interface which allows us to

extend more than one super class.

Syntax for deriving a sub class

class subclassName extends superclassname

{

//define the members

}


42

Aim:

To write a java program to create a package for Book details giving Book name, Author

name, price and year of publishing.

Program:

Step1:

Create a subdirectory inside the root directory which has the same name as the package

you are going to create.

D:\JAVA>md book

Step2:

Create the class of your package with the first statement as the package statement and

save the file with .java extension in the directory created.

/* BookDetails class in package Book */

package book;

public class BookDetails

{

String name,author;

float price;

int year;

public BookDetails(String n,String a,float p,int y)

{

name=n;

author=a;

price=p;

year=y;

}

public void display()

{

Ex. No :6 Packages


43

System.out.println("Book Name :"+name);

System.out.println("Book Author :"+author);

System.out.println("Book Price :Rs "+price);

System.out.println("Year of Publishing:"+year);

}

}

Step 3:

Compile the java file

D:\java>cd book

D:\java\book>javac BookDetails.java

Step 4:

Return to root directory

C:\javapgm\book>cd..

D:\JAVA >

Step 5:

In the main program import the created package into the program using the import

statement and key in the program where we can create instances of the classes in the package.

Save the program in the root directory

Main class:

/* Class that imports book package */

import book.*;

class BookDemo

{


{

BookDetails b=new BookDetails("Java Programming", "Balguruswamy",

190.00f, 2007);

b.display();

}

}


44

Step 6:

Compile and execute the program.

Output:

D:\java>javac BookDemo.java

D:\java>java BookDemo

Book Name :Java Programming

Book Author :Balguruswamy

Book Price :Rs 190.0

Year of Publishing:2007

D:\java>

Viva questions:

What is package?

Package is a collection of interfaces and classes.

How a package can be created?

A package can be created using the package statement.

How a package can be imported into the program?

A package can be imported using the import statement.


45

Aim:

To write a java applet program to change the color of a rectangle using scroll bars to

change the value of red, green and blue.

Algorithm:

1. Import the package Java.awt.*,java.awt.event.*;

2. Create a class that extends Applet and implement Adjustment listener and mouse

motion listener

3. Create three scroll bars

4. Using the scrollbar select value and pass value as argument to the color class

5. Using the color selected draw and fill rectangle

Program:

/* Colour using Scroll bar */

import java.awt.*;

import java.applet.*;

import java.awt.event.*;

/* <applet code="Sbar.class" width=400 height=250 > </applet> */

public class Sbar extends Applet implements AdjustmentListener

{ Scrollbar red,green,blue;

Label l1,l2,l3;

Color col=Color.pink;

int r,g,b;

public void init()

{ setBackground(Color.white);

l1=new Label("Red"); l2=new Label("Green");

l3=new Label("Blue");

red=new Scrollbar(Scrollbar.HORIZONTAL,0,0,0,255);

green=new Scrollbar(Scrollbar.HORIZONTAL,0,0,0,255);

blue=new Scrollbar(Scrollbar.HORIZONTAL,0,0,0,255);

Ex. No :7 Applets and AWT (Scroll bars)


46

setLayout(new FlowLayout());

add(l1); add(red); add(l2);

add(green); add(l3); add (blue);

red.addAdjustmentListener(this);

green.addAdjustmentListener(this);

blue.addAdjustmentListener(this);

}

public void adjustmentValueChanged(AdjustmentEvent e)

{ r=red.getValue();

g=green.getValue();

b=blue.getValue();

col=new Color(r,g,b);

repaint();

}

public void paint(Graphics g)

{ g.setColor(col);

g.fillRect(150,100,100,70);

showStatus("Adjust the Scroll bars to change the color of the

Rectangle");

}

}

Output


47

Aim :

To write an applet program for creating a simple calculator to perform Addition,

Subtraction, Multiplication and Division using Button, Label and TextField component.

Algorithm:

1. Import the package Java.awt.*, java.awt.event.*;

2. Create a class that extends Applet

3. Create two text boxes to enter number

4. Create check box group which contains add, sub, mul, div check boxes.

5. Create a OK button

6. Do the appropriate operations according to the selected check boxes

Program:

/* Calculator using applet */

import java.awt.*;

import java.applet.*;

import java.awt.event.*;

/* <applet code="calci.class" width=400 height=250 > </applet> */

Ex. No :8 Creating a Calculator using Applet


48

public class calci extends Applet implements ActionListener

{

String num[]={"1","2","3","4","5","6","7","8","9",".","0","C"};

String opt[]={"+","-","*","/","="};

Button b1[],b2[];

Panel numpan,oprpan,butpan;

TextField tf=new TextField(20);

double reg1,reg2;

String text,operator;

boolean isNew;

public void init()

{

numpan=new Panel();

numpan.setLayout(new GridLayout(4,3));

b1=new Button[12];

for(int i=0;i<12;i++) //Creating number buttons

{

b1[i]=new Button(num[i]);

numpan.add(b1[i]);

}

oprpan=new Panel();

oprpan.setLayout(new GridLayout(5,1));

b2=new Button[5];

for(int i=0;i<5;i++) //Creating operator buttons

{

b2[i]=new Button(opt[i]);

oprpan.add(b2[i]);

}

setLayout(new BorderLayout());

butpan=new Panel(new GridLayout(1,2));

butpan.add(numpan);


49

butpan.add(oprpan);

add("North",tf);

add("Center",butpan);

reg1=reg2=0.0;

operator=" ";

tf.setText("0");

isNew=true;

for(int i=0;i<12;i++) //Registering the Listeners

b1[i].addActionListener(this);


b2[i].addActionListener(this);

}

public void actionPerformed(ActionEvent e)

{

String cmd=e.getActionCommand();

if(cmd.equals("C")) // Clearing the registers

{

reg1=0.0;

reg2=0.0;

operator="";

tf.setText("0");

isNew=true;

}

else if(isNumber(cmd))

{

if(isNew)

text=cmd;

else

text=tf.getText()+cmd;

tf.setText(text);

isNew=false;


50

}

else if(isOperator(cmd))

{

String val=tf.getText();

reg2=Double.parseDouble(val);

reg1=calculation(operator,reg1,reg2);

Double temp=new Double(reg1);

text=temp.toString();

tf.setText(text);

operator=cmd;

isNew=true;

}

}

/*Method to check whether the button pressed is a number*/

boolean isNumber(String s)

{


{

if (s.equals(num[i]) )

return true;

}

return false;

}

/*Method to check whether the button pressed is a operator*/

boolean isOperator(String s)

{


{

if (s.equals(opt[i]) )

return true;

}


51

return false;

}

/*Method to perform calculation and return the value*/

double calculation(String op,double r1,double r2)

{

if (op.equals("+"))

reg1=reg1+reg2;

else if (op.equals("-"))

reg1=reg1-reg2;

else if (op.equals("*"))

reg1=reg1*reg2;

else if (op.equals("/"))

reg1=reg1/reg2;

else

reg1=reg2;

return reg1;

}

}

Output:


52

Aim :

To write an applet program to draw a bar chart for the following details:

Algorithm:

1. Import the package Java.awt.*, java.awt.event.*;

2. Write the Applet within comment tag in that pass some argument

3. Create a class that extends Applet

4. Draw the bar chart by using the value received by the argument

Program:

Applet Program:

/* Applet to draw a bar chart */

import java.applet.* ;

import java.awt.*;

public class BarChart extends Applet

Ex. No :9 To draw a bar chart using Applet


53

{

int n=0;

String label[];

int value[];

public void init()

{

try

{

n= Integer.parseInt(getParameter("columns"));

label= new String[n];

value= new int[n];

label[0]= getParameter("label1");




value[0]= Integer.parseInt(getParameter("m1"));




}

catch(NumberFormatException e)

{

}

}

public void paint(Graphics g)

{

String msg=label[0];


{

g.setColor(Color.red);

g.drawLine(100,50,100,350);


54

g.drawLine(100,350,300,350);

g.setColor(Color.blue);

g.drawString(label[i],40,145+(50*i));

g.setColor(Color.green);

g.fillRect(100,125+(50*i),value[i] ,30);

showStatus("Bar chart Applet");

}

}

}

HTML files to pass parameter:

<HTML>

<BODY>

<APPLET CODE="BarChart.class" HEIGHT=400 WIDTH=500>

<PARAM name="columns" VALUE=4>

<PARAM name="label1" VALUE="Tamil">

<PARAM name="label2" VALUE="English">

<PARAM name="label3" VALUE="Maths">

<PARAM name="label4" VALUE="Physics">

<PARAM name="m1" VALUE="78">




</APPLET>

</BODY>

</HTML>

Output:


55

Viva Questions:

What is an applet?

Applet is a small interactive java programs that are used for web application.

What are the two packages that are needed to create an applet?

Java.awt and java.applet

What is an applet tag?

Applet tag is an HTML tag that is used to run the java applets.

What is an event?

Events is an interruption given to the running program using input devices such

as mouse, keyboard etc.

What package is needed to handle an event?

java.awt.event

What is the purpose of Scrollbar class?

Scroll bars provide a user interface that is used to scroll through a range of

integer values and also provide methods to read and set these values.

What are the steps needed to handle the event?

1. Import java.awt.event


56

2. Implement the corresponding Event Listener interfaces

3. Register the Event Listeners with the event source.

4. Override the appropriate methods of the listener interfaces.

Aim:

To write a java program for generating two threads, one for generating even number and

one for generating odd number.

Algorithm:

1. Create the classes even,odd that extends Thread

2. Even Thread class is used to print even number

3. Odd Thread class is used to print odd number

4. In the main program start two thread

Program:

class even extends Thread

{

public void run()

{

Ex. No :10 Multithreading (Thread to generate even &odd number)


57

for(int i=0;i<=10;i+=2)

{

System.out.println("Even numbers"+i);

}

}

}

class odd extends Thread

{

public void run()

{

for(int i=1;i<=10;i+=2)

{

System.out.println("Odd numbers"+i);

}

}

}

class mt

{


{

even e=new even();

odd o=new odd();

e.start();

o.start();

}

}

Output:

Even numbers0

Odd numbers1

Even numbers2

Odd numbers3


58

Even numbers4

Odd numbers5

Even numbers6

Odd numbers7

Even numbers8

Odd numbers9

Even numbers10

Viva Questions:

What is thread?

A thread is a single sequential flow of control within a program.

What is multithreading?

Multithreading is the process of running more than one thread at a time.

What are the two ways of creating thread?

A thread can be created by extending Thread class or implementing Runnable

interface.

What are the steps in creating and running thread?

• Declare a class that extends Thread class.

• Implement the run( ) method that is responsible for executing the sequence of

code that the thread will execute.

• Create a thread object in the main class and call the start( ) method to initiate

execution.

What is meant by a synchronization?


59

In multithreaded application, multiple threads might access the data and call methods

simultaneously and this may create problems such as violation of data and unpredictable result.

These problems are referred to as concurrency problems.

Synchronization is the technique that can be used to overcome the concurrency problem

that may arise when two or more threads need to access the shared resources.

Java uses the concept of semaphores (also called monitors) for synchronization. This is

similar to a lock. Whenever a thread is making an attempt to use shared resources, it will lock the

resource (if it is free) and then after using, it will release (open the lock ) the resource.

The keyword synchronized in Java is used for synchronization. This keyword can be used

in two ways ie., a method can synchronized or a block of code can be synchronized.

What is the use of wait and notify methods?

The wait() method is used to move the thread from running state to blocked state. The

notify() method is used to move the thread from blocked state to ready to run state.

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