BlueJ Tutorial

BlueJ Program on Displaying Time In Specific Format

2012-02-07T06:55:00.000+05:30

In this BlueJ program, user will enter time in a specific format like 6,35 or 6,34 where the last two digits represents minutes and the remaining is hour. The program will show the output for the first sample time like 25 Minutes to go to seven.

Here is the BlueJ program on Time

import java.io.*;
class Arr
{
int hr,min;
String str,str1;
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

public void show() throws IOException
{
int rev;
System.out.print("Enter the Time as 6,45: ");
str=br.readLine();
rev=str.indexOf(',');
hr=Integer.parseInt(str.substring(0,rev));
min=Integer.parseInt(str.substring(rev+1));
min=60-min;
str1=String.valueOf(min);
hr=hr+1;
if(str1.charAt(0)!='1')
{
switch(str1.charAt(0))
{
case '2':
System.out.print("Twenty ");
break;
case '3':
System.out.print("Thirty ");
break;

case '4':
System.out.print("Fourty ");
break;

case '5':
System.out.print("Fifty ");
break;
}

switch(str1.charAt(1))
{
case '1':
System.out.print(" One ");
break;
case '2':
System.out.print("Two ");
break;
case '3':
System.out.print("Three ");
break;

case '4':
System.out.print("Four ");
break;

case '5':
System.out.print("Five ");
break;

case '6':
System.out.print("Six ");
break;
case '7':
System.out.print("Seven ");
break;
case '8':
System.out.print("Eight ");
break;

case '9':
System.out.print("Nine ");
break;

}

System.out.print(" Minutes to go to ");
}
else
{
switch(str1.charAt(1))
{
case '1':
System.out.print(" Eleven ");
break;
case '2':
System.out.print("Twelve ");
break;
case '3':
System.out.print("Thirteen ");
break;

case '4':
System.out.print("Fourteen ");
break;

case '5':
System.out.print("Fifteen ");
break;

case '6':
System.out.print("Sixteen ");
break;
case '7':
System.out.print("Seventeen ");
break;
case '8':
System.out.print("Eighteen ");
break;
case '9':
System.out.print("Nineteen ");
break;

}

System.out.print(" Minutes to go to ");
}

switch(hr)
{
case 1:
System.out.print(" One ");
break;
case 2:
System.out.print("Two ");
break;
case 3:
System.out.print("Three ");
break;

case 4:
System.out.print("Four ");
break;

case 5:
System.out.print("Five ");
break;

case 6:
System.out.print("Six ");
break;
case 7:
System.out.print("Seven ");
break;
case 8:
System.out.print("Eight ");
break;

case 9:
System.out.print("Nine ");
break;

}

}
}

ICSE 2012 Computer Application Paper Expected Questions - Last Minute Suggestions Part I

2012-02-02T16:42:00.000+05:30

Few question and answers are given below. Students can expect these type of questions in ICSE 2012 Computer Application examination.

What do you mean by data encapsulation and polymorphism in Java?

Data encapsulation means hiding the data members of an object using the function members so that the data mebers are prevented from unauthorized access.

Polymorphism is one of the OOP principles by virtue of which different operators or different functions exihibit different behavior while used in different environments. Polymorphism are of three types: Function overloading, function overring and operator overloading.

What is casting, when do we need it? Give an example.

Casting means converting variables or objects from one type to another type. Casting are of two types, automatic or implicit casting and forceful or explicit casting.

Sometimes we work on two variables of same type but the result required is of different type. In such situation casting is needed.

For example, suppose runs scored by a batsman is stored in variable ‘a’ and total innings played by the batsman and total notout are stored in ‘b’ and ‘c’ respectively. Now all these values are of ‘int’ type. We need to calculate the average score of the batsman. If we use the statement like double av=a/(b-c); the result would not be accurate. In this situation explicit casting is needed. Double av=(double)a/(b-c);

Name the package you need to import for using Scanner class object.

Scanner class is stored in util package which is again under java package.

State the difference between while and do-while loop

While loop is entry control loop while do-while loop is exit control type of loop. In while loop no semicolon is required after the control statement but in do-while loop, semicolon after the control statement is a must.

State the difference between constructor and function

Constructor is a special function whose name must be same as the class name. Function name must be different from the class name.

Constructor has no return type, not even void while functions maust have a return type.

If constructor is not defined in a class, compiler supplies default constructor. Default constructor means constructor with no argument and empty body. There is no such case with functions.

Explain any two type of access specifiers

There are four type of access specifiers in java and two of them are public and private. The specifiers can be used before class name, variable and function declaration. Public class, function or data member means which can be accessed from anywhere, even from outside the package where the class is defined.

Private data members and function members are only accessible within the class body.

What are the preconditions of binary search?

There are two preconditions of binary search, the first one is that the elements in the list must be in sorted order and the second precondition is about the accessibility of the middle location of list directly. That’s why binary search is applicable only in array.

What is the role of void keyword in declaration of a function

Void keyword in a function specifies that the function will not return any value to the calling program after execution.

Write the name and syntax of the function which is used to extract multiple characters from strings.

‘String substring (int start, int end)’ function of String class is used to extract multiple characters from strings. ‘int start’ denotes the index from where the sub-string will be extracted and ‘int end’ denotes end location of the string upto which the characters will be extracted.

What is package, give example

Package are containers of classes, abstract classes and interfaces. Package may contain packages also but ultimately they contain classes, abstract classes and interfaces. Example of packages are ‘lang’ package, ‘io’ package etc.

Find the output of the following code segments:

int a=0,b=0;

for(a=0;a<=5;a+=2)

for(b=0;b<=a;++b)

System.out.println(“Answer1:”+(++a)+b++);

System.out.println(“Answer2:”+(++a)+b++);

Output:

Answer1:10

Answer1:30

Answer1:42

Answer1:54

Answer2:76

Output of the following code segment:

int I,j,arr[]=new int[7];

arr[0]=1;

for(i=0;i<6;i++)

{

for(j=i+1;j>0;j--)

arr[j]=arr[j]+arr[j-1];

System.out.println();

}

Output: Six blank lines

Following program segment is to print the the sum of the prime digits of an entered number:

For example, if entered number is 1872, the output will be – sum of the prime digitd is 9 ( as 7 and 2 are two prime digits in 1872)

int digit,sum=0,n=1872;

while(n>0)

{

?1?=n%10;

If(digit==2||?2?||?3?||digit==7)

sum=?4?;

n=n/10;

}

System.out.println(“Sum of prime digits is”+sum);

Fill up the statements marked with question mark.

?1?: digit

?2?: digit==3

?3?: digit==5

?4?: sum+digit

What is private visibility of a method

Private function means which can not be accessed from outside the class body. Private functions can be invoked by other functions defined in a class only.

Explain function overloading with example

Function overloading means where function names must be same and argument list of the functions should be different. The return type of the functions can be same or different. Function overloading is possible in same class as well as in sub classes.

void change ()

{

System.out.println(“Nothing to change…”);

}

void change ( int a, int b)

{

a=a+b;

b=a-b;

a=a-b;

System.out.println(“Values changed =” + a + “,”+b);

}

What does System.in and System.out refers to

System.in is inbuilt input object where the terminal input value is stored in byte. System.out is the inbuilt output object whose functions like println () and print () are used for terminal output.

What is exit control loop? Give example

Exit control loop is that type of loop where body of the loop appears before the control statement of the loop. Do or do-while loop is an example of exit control loop. In such type of loop, loop body execution for at least once is confirmed as the control enters the loop body in the first iteration with out checking any condition.

What is recursive function, give example

Recursive functions are those specific functions where the function is called repetadely from a state,ment used within the body of the function itself. A base value is needed in recursive function to stop the calling.

Write a statement to import a class ‘Nano’ under the package ‘Car’ which is again under the package ‘Tata’ and Tata is under ‘Indian’ package

import Indian.Tata.Car.Nano;

What will be the output of the following program segment?

String name[]={“Computer”,”Application”};

System.out.println(name[0].length());

System.out.println(name.length);

First output: 8 as length of Computer is 8.

Second output is 2 as there are two elements in the array name.

Give the output:

class Outt

{

public void av()

{

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

{

If(i==6)

Break;

}

System.out.println(i);

}

Output: 6

Give the output:

TuTOrIaI”.indexOf(‘I’);

Math.rint(-38.96);

Math.abs(4789.45);

Math.max(Math.min(15,25),5);

(int)(“Scholar”.charAt(2));

Math.ceil(-28.25);

“MISSISSIPPI”.lastIndexOf(‘S’);

Math.floor(-524.99);

“suddhashil”.substring(3,4);

Math.sqrt(100);

Output:

-39.0

4789.45

104

-28.0

-525.0

10.0

Another set of suggestions for ICSE 2012 Computer Application will be posted very soon.

BlueJ Program on Perfect Number Checking Of A Number Or Its Nearest Number

2012-01-30T18:39:00.001+05:30

In this program user will enter a number and the program will show whether it is a perfect number. If the entered number is not a perfect number then the nearest higher value of the entered number which is a perfect number will be displayed.

BlueJ Codes of the Perfect Number Checking Program

import java.io.*;

class border

{

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

int i,s,n,j;

public void take()throws IOException

{

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

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

j=n;

s=0;

for(i=1;i< n;i++)

{

if(n%i==0)

s=s+i;

}

if(s==n)

System.out.println("Number = "+ n + " is a perfect number");

else

{

s=0;

n++;

while(true)

{

for(i=1;i< n;i++)

{

if(n%i==0)

s=s+i;

}

if(s==n)

{

System.out.println(n+ " is perfect number nearest to "+j);

break;

}

else

{

s=0;

n++;

}

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

{

border ob=new border();

ob.take();

}

Technical Analysis of the perfect number program using BlueJ

If the entered number is a perfect number then the matter is solved otherwise an infinite while loop is executed and the entered number is incremented by one every time the new number is found not perfect number. When the incremented number is found to be perfect number, the result is displayed and the infinite loop is terminated.

Sample Input and Output of the perfect number program

Enter the number:

28 is perfect number nearest to 7

Enter the number:

Number = 28 is a perfect number

Enter the number:

6 is perfect number nearest to 5

Related posts:

Program on possible consecutive numbers

Program on Perfect Number

Program on Automorphic Number

Program on Saddle Number

Program on Armstrong Number

Menu Driven BlueJ Program on Odd, Even and Perfect Numbers

2012-01-12T15:25:00.002+05:30

The question here is that, Write a BlueJ program which will ask the user to enter a choice and based on the choice the following operation will take place.

if choice=1; then sum of even nos. from the series of 10 nos.

if choice=2; then sum of odd nos. from a series of 10 nos.

if choice=3; then it will check whether the no is perfect or not from a series of 10 nos.

Codes of the Menu driven BlueJ Program

import java.io.*;

class Menu

{

BufferedReader br;

int arr[]=new int[10];

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

{

Menu ob=new Menu ();

ob.accept();

}

Menu ()

{

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

}

public void accept()throws IOException

{

int choice;

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

{

System.out.println("Enter number:");

arr[i]=Integer.parseInt(br.readLine().trim());

}

System.out.println("Enter Your Choice (1 for adding even numbers, 2 for adding odd number and 3 for checking perfect number:");

choice=Integer.parseInt(br.readLine().trim());

if(choice==1)

addEven();

else if(choice==2)

addOdd();

else if(choice==3)

showPerfect();

else

System.out.println("Wrong Choice:");

}

private void addEven()

{

int sum=0;

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

{

if(arr[i]%2==0)

sum=sum+arr[i];

}

System.out.println("Sum of Even Numbers="+sum);

}

private void addOdd()

{

int sum=0;

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

{

if(arr[i]%2!=0)

sum=sum+arr[i];

}

System.out.println("Sum of Odd Numbers="+sum);

}

private void showPerfect()

{

int sum;

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

{

sum=0;

for(int j=1;j< arr[i];j++)

{

if(arr[i]%j==0)

sum=sum+j;

}

if(sum==arr[i])

System.out.println(arr[i]+ " is a Prefect Number");

}

Sample input and output of the BlueJ program

Enter number:

Enter Your Choice (1 for adding even numbers, 2 for adding odd number and 3 for checking perfect number:

6 is a Prefect Numbers

Enter number:

Enter Your Choice (1 for adding even numbers, 2 for adding odd number and 3 for checking perfect number:

Sum of Even Numbers=26

BlueJ Program on Changing Upper Case Characters to Lower Case Using Recursive Function

2012-01-11T15:17:00.001+05:30

In this BlueJ program on string manipulation, the entered text will be modified in such a way that all the upper case characters in the sentence will be converted into lower case characters. Other characters, lower case characters and punctuations will remain unchanged.

Codes of the BlueJ program on string manipulation

import java.io.*;

class Words2

{

BufferedReader br;

String text,s1="";

int len,i;

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

{

Words2 ob=new Words2();

ob.accept();

}

Words2()

{

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

}

public void accept()throws IOException

{

System.out.println("Enter the sentence:");

text=br.readLine().trim();

len=text.length();

i=0;

result(text,i);

System.out.println(“Modified string=”+s1);

}

public void result(String s,int i)

{

if(i==len)

return;

if(s.charAt(i)>=65 && s.charAt(i)<=90)

s1=s1+=(char)(s.charAt(i)+32);

else

s1=s1+s.charAt(i);

i++;

result(s,i);

}

Technical Analysis of the BlueJ Program on string manipulation

The function ‘public void accept()’ accepts the sentence from the user and the sentence along with a variable with initial value ‘0’ is passed to another function ‘public void result(String s,int i)’ which is the recursive function. The variable with initial value will access the characters of the sentence one by one within the recursive function. ‘String s1’ is an object of string class which will store the modified value. The characters in the sentence are accessed and checked for upper case and if found necessary changes are done. Simultaneously the string object ‘s1’ is updated and the value of the variable ’i’ is incremented by 1. When the value of ‘i’ becomes equal to the length of the sentence, recursive call is stopped.

Sample input and output of the BlueJ program on string manipulation

Enter the sentence:

This is TEST on Case Changing Program.

this is test on case changing program.

BlueJ program on input and output restrictred Dequeue

2011-12-20T20:17:00.000+05:30

import java.io.*;

public class stack

{

int arr[]=new int[10];

int f,r;

int i,n;

int check;

String str;

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

stack()

{

f=-1;

r=-1;

}

public void status() throws Exception

{

System.out.println("\nEnter '1' for Input restricted Dequeue, '2' for Output restricted Dequeue:");

check=Integer.parseInt(br.readLine());

}

public void push() throws IOException

{

if(r==9)

{

System.out.println("Queue overflow...");

return;

}

if(check!=1)

{

System.out.println("Specify the location ( Front or rear):");

str=br.readLine().toLowerCase();

}

else

str="r";

System.out.println("Enter the value to insert: ");

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

if(f==-1)

{

arr[++f]=n;

r=0;

}

else if(str.charAt(0)=='f')

{

for(i=r+1;i>f;i--)

arr[i]=arr[i-1];

arr[i]=n;

r++;

}

else

{

arr[++r]=n;

}

public void display()

{

if(f==-1)

return;

for(i=f;i<=r;i++)

System.out.print(" "+arr[i]);

}

public void pop() throws IOException

{

if(f==-1)

{

System.out.println("Queue Underflow...");

return;

}

if(check!=2)

{

System.out.println("Specify the location ( Front or rear):");

str=br.readLine().toLowerCase();

}

else

str="f";

if(f==r)

{

f=-1;

r=-1;

}

else if(str.charAt(0)=='f')

{

f++;

}

else

{

r--;

}

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

{

char op;

BufferedReader br;

stack ob=new stack();

ob.status();

while(true)

{

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

System.out.println("\nPress 'p' for push, 'd' for pop and 'q' for quite:");

op=(char)br.read();

if(op=='p')

ob.push();

else if(op=='d')

ob.pop();

ob.display();

if(op=='q')

break;

br=null;

}

Menu driven BlueJ program on simple calculator

2011-12-20T20:15:00.000+05:30

import java.io.*;

public class Pat

{

int a,b,c;

char ch;

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

public void init()throws Exception

{

System.out.println("Enter first number:");

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

System.out.println("Enter second number:");

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

System.out.println("Enter operator (+,-,*,/):");

ch=(char)br.read();

switch(ch)

{

case '+':

add();

break;

case '-':

sub();

break;

case '*':

product();

break;

case '/':

if(b==0)

System.out.println("Division not possible");

else

div();

break;

default:

System.out.println("Wrong Operator");

}

private void add()

{

c=a+b;

System.out.println("Sum="+c);

}

private void sub()

{

c=a-b;

System.out.println("Subtracted value="+c);

}

private void product()

{

c=a*b;

System.out.println("Product="+c);

}

private void div()

{

c=a/b;

System.out.println("Divided result="+c);

}

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

{

Pat ob=new Pat();

ob.init();

}

Sample input and output of the menu driven calculator program

Enter first number:

Enter second number:

Enter operator (+,-,*,/):

Sum=55

BlueJ Program on showing frequency of characters in a sentence

2011-12-18T19:07:00.003+05:30

import java.io.*;

class Words2

{

BufferedReader br;

String text;

char ch[];

int len;

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

{

Words2 ob=new Words2();

ob.accept();

ob.result();

}

Words2()

{

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

}

public void accept()throws IOException

{

System.out.println("Enter the sentence:");

text=br.readLine().trim();

len=text.length();

ch=new char[len];

text.getChars(0,len,ch,0);

}

public void result()

{

int i,j;

char ch1;

int w;

for(i=0;i< len-1;i++)

{

for(j=i+1;j< len;j++)

{

if(ch[i] >ch[j])

{

ch1=ch[i];

ch[i]=ch[j];

ch[j]=ch1;

}

ch1=ch[0];

System.out.println(ch1);

w=1;

for(i=1;i< len;i++)

{

if(ch1==ch[i])

w++;

else

{

if(ch1==' ')

System.out.println("Frequency of space="+w);

else

System.out.println("Frequency of "+ch1+" ="+w);

w=1;

ch1=ch[i];

}

System.out.println("Frequency of "+ch1+" ="+w);

}

Technical analysis of the program on calculating frequency of letters

The sentence is first stored in a character type array so that the characters can be sorted. Next the frequency is computed using the same technique as the frequency calculation of digits in a numbers.

Sample input and output of the BlueJ program on showing frequency

Enter the sentence:

this is a test of frequency

Frequency of space=5

Frequency of a =1

Frequency of c =1

Frequency of e =3

Frequency of f =2

Frequency of h =1

Frequency of i =2

Frequency of n =1

Frequency of o =1

Frequency of q =1

Frequency of r =1

Frequency of s =3

Frequency of t =3

Frequency of u =1

Frequency of y =1

BlueJ program on Dequeue

2011-12-13T09:20:00.003+05:30

First of all we should have some idea about Deque. Queue means where insertion are normally done at the rear end and deletion is done from the front end. Dequeue is a special type of queue where insertion and deletion can be done from both the ends but no operation is permitted at the middle.

Here is the BlueJ program on Dequeue

import java.io.*;

public class stack

{

int arr[]=new int[10];

int f,r;

int i,n;

String str;

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

stack()

{

f=-1;

r=-1;

}

public void push() throws IOException

{

if(r==9)

{

System.out.println("Queue overflow...");

return;

}

System.out.println("Specify the location ( Front or rear):");

str=br.readLine().toLowerCase();

System.out.println("Enter the value to insert: ");

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

if(f==-1)

{

arr[++f]=n;

r=0;

}

else if(str.charAt(0)=='f')

{

for(i=r+1;i>f;i--)

arr[i]=arr[i-1];

arr[i]=n;

r++;

}

else

{

arr[++r]=n;

}

public void display()

{

if(f==-1)

return;

for(i=f;i<=r;i++)

System.out.print(" "+arr[i]);

}

public void pop() throws IOException

{

if(f==-1)

{

System.out.println("Queue Underflow...");

return;

}

System.out.println("Specify the location ( Front or rear):");

str=br.readLine().toLowerCase();

if(f==r)

{

f=-1;

r=-1;

}

else if(str.charAt(0)=='f')

{

f++;

}

else

{

r--;

}

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

{

char op;

BufferedReader br;

stack ob=new stack();

while(true)

{

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

System.out.println("\nPress 'p' for push, 'd' for pop and 'q' for quite:");

op=(char)br.read();

if(op=='p')

ob.push();

else if(op=='d')

ob.pop();

ob.display();

if(op=='q')

break;

br=null;

}

Technical analysis of the BlueJ program on Dequeue

In this BlueJ program on Dequeue, I have taken array of size 10. The array will be used to perform the job of Dequeue in this program. Normally Queue or Dequeues are dynamic in nature, any number of values can be inserted in them. Array has some limitations, insertion can not exceed the size of the array.

Two variables ‘f’ and ‘r’ are taken in this BlueJ program on Dequeue to perform the push and pop operations. The variable ‘f’ will access the front location of the array and ‘r’ will access the rear location. Initially both are set to ‘0’.

While pushing values at rear end, the insertion is performed very easily just like setting values in an array but while values are inserted at the front location, the values are shifted one step to right to make room for the new value at the ‘0’ index.

Pop operations in this BlueJ program on Dequeue is performed by either increasing the value of ‘f’ or decreasing the value of ‘r’ as directed by user.

Sample input and output of BlueJ program on Dequeue

Press 'p' for push, 'd' for pop and 'q' for quite:

Specify the location ( Front or rear):

Enter the value to insert:

100

Press 'p' for push, 'd' for pop and 'q' for quite:

Specify the location ( Front or rear):

Enter the value to insert:

200

200 100

Press 'p' for push, 'd' for pop and 'q' for quite:

Specify the location ( Front or rear):

Enter the value to insert:

200 100 30

Press 'p' for push, 'd' for pop and 'q' for quite:

Specify the location ( Front or rear):

100 30

Press 'p' for push, 'd' for pop and 'q' for quite:

Specify the location ( Front or rear):

Enter the value to insert:

500

500 100 30

Press 'p' for push, 'd' for pop and 'q' for quite:

Specify the location ( Front or rear):

Enter the value to insert:

600

600 500 100 30

Press 'p' for push, 'd' for pop and 'q' for quite:

Suggestions on Computer paper for ICSE stidents of 2012

2011-11-29T06:58:00.000+05:30

In this post few questions with answers, theory part are posted for ICSE students of 2012. Read these answers and if any doubt, post your comments.

What is private and public specifier in Java?

public and private are access specifiers used before variable declaration and function definition. ‘public’ members, whether used in function or variable can be accessed from outside the class body even outside the package while ‘private’ members can be accessed from only within the class body.

Difference between ‘==’ and equals ()’.

‘==’ is an operator, relational operator used to compare equality of two primitive values and when this operator is used on objects, it compares the references of the objects for equality.

‘euqals ()’ is a String class function and prototype of this function is ‘boolean equals(String s)’. This function takes a String object as argument and compares the argument object and invoking object values for equality. This is a case sensitive function.

Compare switch with else-if ladder.

Both switch and else-if are decision making statements which can operate successfully on multiple options. There are some differences between these two decision making statements.

else-if can work on any type of primitive values and objects while switch can work only on character and integer value.

In switch statement, logical operator can not be used while in else-if ladder, logical operators are used.

The statement ‘break’ is required at the end of each case body to send the control out of switch body while in case of else-if ladder, no such break statement is required.

else is optional part of else-if ladder and default is option part of switch statement. In else-if ladder, else has to be placed at the end of the ladder and in switch, default is normally placed at the end but it can be placed anywhere in the switch body.

Switch works

4. Define ‘substring ()’ and ‘charAt()’ function.

‘substring ()’ is a function of String class and return type of this function is String. This function has two overloaded versions. The prototypes are ‘String substring (int start)’ and ‘String substring (int start, int number)’.

‘charAt ()’ is a function of String class and prototype of the function is ‘char charAt(int i)’. This function returns the character of the specified location ‘I’ of the invoking string object.

Comparision between break and continue

Both are jumoing statements while braek is used in loop and switch statements, continue is used on in loops. Break is used in loops for premature termination of the loop and the same statement is used in case body of switch statement to send the control out of switch body.

Continue is used in loops for premature iteration of the loop, means loop body starts executing skipping a part of statements in the loop body.

Use of ‘this’ keyword.

‘this’ is a keyword used in java to refer the current object.

Define entry control and exit control loop

In entry control loops, the control statement appears before the body of the loop and in exit control loop, it is just the reverse. In exit control loop, body is first executed and then the condition is evaluated.

BlueJ program on arranging the digits of a number in ascending order

2011-11-22T04:39:00.002+05:30

This is a BlueJ program on rearranging the digits of number in ascending order. Suppose the entered number is 2314 then the output will be 1234.

Codes of the program

import java.io.*;

class Num1

{

int arr[]=new int[10];

int i,j,t,n,x=0,rev=0;

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

public void take() throws IOException

{

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

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

System.out.println("Entered Number="+n);

while(n>0)

{

arr[x++]=n%10;

n=n/10;

}

for(i=0;i< x-1;i++)

{

for(j=i+1;j< x;j++)

{

if(arr[i]>arr[j])

{

t=arr[i];

arr[i]=arr[j];

arr[j]=t;

}

for(i=0;i< x;i++)

{

rev=rev*10+arr[i];

}

System.out.println("The number in modified form="+rev);

}

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

{

Num1 ob=new Num1();

ob.take();

}

In this program, digits from the entered number are retrieved and stored in an array. The array is then sorted in ascending order and from the array the digits are retrieved and a new number is formed.

Sample input and output of the program

Enter the Number:261

Entered Number=261

The number in modified form=126

Enter the Number:9715

Entered Number=9715

The number in modified form=1579

BlueJ program to find the total number of days between two dates

2011-11-15T15:59:00.003+05:30

In this BlueJ program, two dates in dd/mm/yyyy format are to be entered and the total number of days between the dates will be calculated and displayed.

Codes of the program

import java.io.*;

class Array1

{

int arr[]={ 31,28,31,30,31,30,31,31,30,31,30,31};

int d1=-1,m1=-1,y1,d2=-1,m2=-1,y2,days=0,mon1,mon2;

int i,j;

String str,start,end;

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

public void take() throws IOException

{

System.out.print("Enter the start date in dd/mm/yyyy format:");

start=br.readLine();

System.out.print("Enter the end date in dd/mm/yyyy format:");

end=br.readLine();

while(true)

{

i=start.indexOf("/");

if(i< 0)

break;

str=start.substring(0,i);

if(d1==-1)

d1=Integer.parseInt(str);

else if(m1==-1)

m1=Integer.parseInt(str);

start=start.substring(i+1);

}

y1=Integer.parseInt(start);

while(true)

{

i=end.indexOf("/");

if(i< 0)

break;

str=end.substring(0,i);

if(d2==-1)

d2=Integer.parseInt(str);

else if(m2==-1)

m2=Integer.parseInt(str);

end=end.substring(i+1);

}

y2=Integer.parseInt(end);

days=arr[m1-1]-d1;

days=days+d2;

m2=m2-1;

mon2=m2;

for(i=y1;i< =y2;i++)

{

if(i!=y1)

m1=0;

if(i!=y2)

m2=12;

else if(i==y2)

m2=mon2;

for(j=m1;j< m2;j++)

{

days=days+arr[j];

}

if(leap(i) && m2>2)

days++;

}

System.out.println("Total number of days="+days);

}

private boolean leap(int yyyy)

{

if(yyyy%100==0 && yyyy%400==0)

return true;

else if(yyyy%100!=0 && yyyy%4==0)

return true;

else

return false;

}

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

{

Array1 ob=new Array1();

ob.take();

}

Technical analysis of this program

Two dates are taken and the day,month and year of the dates are extracted and stored in variables like ‘d1’,’m1’,’y1’, ‘d2’,’m2’,’y2’. The number of days of each month are stored in a array. The counter variable, here ‘days’ in the program is initialized with the remaining number of days of the first month of the starting date plus number of days of the last month of the ending date. The days inbetween the starting and ending dates are stored in the counter variable using a loop. For leap year checking a function is defined in this program.

Sample input and output of the program

Enter the start date in dd/mm/yyyy format:1/1/2010

Enter the end date in dd/mm/yyyy format:1/4/2011

Total number of days=455

Enter the start date in dd/mm/yyyy format:1/1/2010

Enter the end date in dd/mm/yyyy format:1/1/2012

Total number of days=730

Students Result Report - Project for ICSE students on BlueJ

2011-11-14T09:11:00.000+05:30

This program is on displaying result of any class having 13 subjects. This BlueJ program can be considered as a project job for ICSE students. Stuudents have to appear in two semester examination, each semester having Unit1, Unit2 and Block examination. From the score, percentage of marks will be calculated and result will be displayed from top to bottom. Result of any individual student can also be accessed.

import java.io.*;

class Report

{

String name[]=new String[100];

String roll[]=new String[100];

int marks[][]=new int[100][9];

int std;

/* (unit1,unit2,block,total)*2 plus grand total*/

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

int i;

public void setMarks() throws IOException

{

System.out.println("How many students?:");

std=Integer.parseInt(br.readLine());

for(i=0;i< std;i++)

{

System.out.println("Enter Name of Student No " +(i+1) + ":");

name[i]=br.readLine();

System.out.println("Enter Roll No:");

roll[i]=br.readLine();

System.out.println("Semester 1");

sem1();

System.out.println("Semester 2");

sem2();

}

sort();

}

private void sem1() throws IOException

{

int m,n;

int d=0,d1=0;

System.out.println("Unit1");

for(m=0;m< 13;m++)

{

if(m==0)

System.out.println("Subject1:");

else if(m==1)

System.out.println("Subject2:");

else if(m==2)

System.out.println("Subject3:");

else if(m==3)

System.out.println("Subject4:");

else if(m==4)

System.out.println("Subject5:");

else if(m==5)

System.out.println("Subject6:");

else if(m==6)

System.out.println("Subject7:");

else if(m==7)

System.out.println("Subject8:");

else if(m==8)

System.out.println("Subject9:");

else if(m==9)

System.out.println("Subject10:");

else if(m==10)

System.out.println("Subject11:");

else if(m==11)

System.out.println("Subject12:");

else if(m==12)

System.out.println("Subject13:");

d=d+Integer.parseInt(br.readLine());

}

d1=d1+d;

marks[i][0]=d;

d=0;

System.out.println("Unit2");

for(m=0;m< 13;m++)

{

if(m==0)

System.out.println("Subject1:");

else if(m==1)

System.out.println("Subject2:");

else if(m==2)

System.out.println("Subject3:");

else if(m==3)

System.out.println("Subject4:");

else if(m==4)

System.out.println("Subject5:");

else if(m==5)

System.out.println("Subject6:");

else if(m==6)

System.out.println("Subject7:");

else if(m==7)

System.out.println("Subject8:");

else if(m==8)

System.out.println("Subject9:");

else if(m==9)

System.out.println("Subject10:");

else if(m==10)

System.out.println("Subject11:");

else if(m==11)

System.out.println("Subject12:");

else if(m==12)

System.out.println("Subject13:");

d=d+Integer.parseInt(br.readLine());

}

d1=d1+d;

marks[i][1]=d;

d=0;

System.out.println("Block");

for(m=0;m<13;m++)

{

if(m==0)

System.out.println("Subject1:");

else if(m==1)

System.out.println("Subject2:");

else if(m==2)

System.out.println("Subject3:");

else if(m==3)

System.out.println("Subject4:");

else if(m==4)

System.out.println("Subject5:");

else if(m==5)

System.out.println("Subject6:");

else if(m==6)

System.out.println("Subject7:");

else if(m==7)

System.out.println("Subject8:");

else if(m==8)

System.out.println("Subject9:");

else if(m==9)

System.out.println("Subject10:");

else if(m==10)

System.out.println("Subject11:");

else if(m==11)

System.out.println("Subject12:");

else if(m==12)

System.out.println("Subject13:");

d=d+Integer.parseInt(br.readLine());

}

d1=d1+d;

marks[i][2]=d;

marks[i][3]=d1;

}

private void sem2() throws IOException

{

int m,n;

int d=0,d1=0;

System.out.println("Unit1");

for(m=0;m< 13;m++)

{

if(m==0)

System.out.println("Subject1:");

else if(m==1)

System.out.println("Subject2:");

else if(m==2)

System.out.println("Subject3:");

else if(m==3)

System.out.println("Subject4:");

else if(m==4)

System.out.println("Subject5:");

else if(m==5)

System.out.println("Subject6:");

else if(m==6)

System.out.println("Subject7:");

else if(m==7)

System.out.println("Subject8:");

else if(m==8)

System.out.println("Subject9:");

else if(m==9)

System.out.println("Subject10:");

else if(m==10)

System.out.println("Subject11:");

else if(m==11)

System.out.println("Subject12:");

else if(m==12)

System.out.println("Subject13:");

d=d+Integer.parseInt(br.readLine());

}

d1=d1+d;

marks[i][4]=d;

d=0;

System.out.println("Unit2");

for(m=0;m<13;m++)

{

if(m==0)

System.out.println("Subject1:");

else if(m==1)

System.out.println("Subject2:");

else if(m==2)

System.out.println("Subject3:");

else if(m==3)

System.out.println("Subject4:");

else if(m==4)

System.out.println("Subject5:");

else if(m==5)

System.out.println("Subject6:");

else if(m==6)

System.out.println("Subject7:");

else if(m==7)

System.out.println("Subject8:");

else if(m==8)

System.out.println("Subject9:");

else if(m==9)

System.out.println("Subject10:");

else if(m==10)

System.out.println("Subject11:");

else if(m==11)

System.out.println("Subject12:");

else if(m==12)

System.out.println("Subject13:");

d=d+Integer.parseInt(br.readLine());

}

d1=d1+d;

marks[i][5]=d;

d=0;

System.out.println("Block");

for(m=0;m<13;m++)

{

if(m==0)

System.out.println("Subject1:");

else if(m==1)

System.out.println("Subject2:");

else if(m==2)

System.out.println("Subject3:");

else if(m==3)

System.out.println("Subject4:");

else if(m==4)

System.out.println("Subject5:");

else if(m==5)

System.out.println("Subject6:");

else if(m==6)

System.out.println("Subject7:");

else if(m==7)

System.out.println("Subject8:");

else if(m==8)

System.out.println("Subject9:");

else if(m==9)

System.out.println("Subject10:");

else if(m==10)

System.out.println("Subject11:");

else if(m==11)

System.out.println("Subject12:");

else if(m==12)

System.out.println("Subject13:");

d=d+Integer.parseInt(br.readLine());

}

d1=d1+d;

marks[i][6]=d;

marks[i][7]=d1;

marks[i][8]=marks[i][3]+marks[i][7];

}

public void showResult()

{

double d=0;

int j;

System.out.println("Name Roll Unit1 Unit2 Block Total Unit1 Unit2 Block Total Percentage");

for(i=0;i< std;i++)

{

System.out.print(name[i]+ " "+roll[i]);

for(j=0;j< 9;j++)

{

System.out.print(marks[i][j]+ " ");

}

d=marks[i][8]/2.0;

System.out.print(d);

System.out.println();

}

private void sort()

{

int j,temp;

String s;

for(i=0;i< std-1;i++)

{

for(j=i+1;j< std;j++)

{

if(marks[i][8]< marks[j][8])

{

s=name[i];

name[i]=name[j];

name[j]=s;

s=roll[i];

roll[i]=roll[j];

roll[j]=s;

temp=marks[i][0];

marks[i][0]=marks[j][0];

marks[j][0]=temp;

temp=marks[i][1];

marks[i][1]=marks[j][1];

marks[j][1]=temp;

temp=marks[i][2];

marks[i][2]=marks[j][2];

marks[j][2]=temp;

temp=marks[i][3];

marks[i][3]=marks[j][3];

marks[j][3]=temp;

temp=marks[i][4];

marks[i][4]=marks[j][4];

marks[j][4]=temp;

temp=marks[i][5];

marks[i][5]=marks[j][5];

marks[j][5]=temp;

temp=marks[i][6];

marks[i][6]=marks[j][6];

marks[j][6]=temp;

temp=marks[i][7];

marks[i][7]=marks[j][7];

marks[j][7]=temp;

temp=marks[i][8];

marks[i][8]=marks[j][8];

marks[j][8]=temp;

}

public void display(String str)

{

int j;

for(i=0;i< std;i++)

{

if(roll[i].equalsIgnoreCase(str))

{

System.out.print(name[i]+ " "+roll[i]);

for(j=0;j< 9;j++)

System.out.print(marks[i][j]+ " ");

break;

}

if(i==std)

System.out.println("Invalid Roll Number.");

}

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

{

String ans="y";

String r;

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

Report ob=new Report();

ob.setMarks();

while(!ans.equalsIgnoreCase("n"))

{

System.out.println("\nEnter the Roll Number to display result:");

r=br.readLine();

ob.display(r);

System.out.println("\nAny more student:(y/n):");

ans=br.readLine();

}

ob.showResult();

}

BlueJ program on re-arranging numbers in an array with positive numbers first

2011-11-14T05:00:00.000+05:30

In this BlueJ program, , user will enter values in an array and after re-arranging the values, the positive numbers will be set first and then the negative values. In the first program, a separate array is used to re-arrange the values.

Codes of the program.

import java.io.*;

class Array1

{

int arr[]=new int[10];

int arr1[]=new int[10];

int i,x=0;

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

public void take() throws IOException

{

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

{

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

arr[i]=Integer.parseInt(br.readLine());

}

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

{

if(arr[i]>=0)

arr1[x++]=arr[i];

}

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

{

if(arr[i]<0)

arr1[x++]=arr[i];

}

System.out.println("\nArranged array is=");

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

System.out.print(" "+arr1[i]);

}

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

{

Array1 ob=new Array1();

ob.take();

}

Here after taking the values, the positive numbers are set in the second array first and then the negative number. This technique involves the use of a second array.

Sample input and output of the program

Enter the Number:33

Enter the Number:22

Enter the Number:33

Enter the Number:44

Enter the Number:-23

Enter the Number:2

Enter the Number:-89

Enter the Number:33

Enter the Number:-8

Enter the Number:12

Arranged array is=

33 22 33 44 2 33 12 -23 -89 -8

Re-arranging numbers without using second array

This is the modified version of the above program. The same job will done but no second array is used here.

import java.io.*;

class Array1

{

int arr[]=new int[10];

int i,j,n,k;

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

public void take() throws IOException

{

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

{

System.out.print("\nEnter the Number:");

arr[i]=Integer.parseInt(br.readLine());

}

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

{

if(arr[i]>=0)

continue;

for(j=i+1;j<10;j++)

{

if(arr[j]>=0)

{

n=arr[j];

break;

}

if(j!=10)

{

for(k=j;k>i;k--)

{

arr[k]=arr[k-1];

}

arr[k]=n;

}

System.out.println("\nArranged array is=");

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

System.out.print(" "+arr[i]);

}

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

{

Array1 ob=new Array1();

ob.take();

}

Technical analysis of this BlueJ program

After entering the values in an array, the numbers are searched for negative and if not found the process is continues. If any negative number is found, the next positive number is searched and if any positive number is found, it is stored in a temporary variable and the numbers which lies between the negative number and the positive number are moved one step right. At the end the positive values found which was stored in a temporary variable is set ion the location of the negative number for whom the process started. The same process is continues for all numbers.

Sample input and output

Enter the Number:3

Enter the Number:-8

Enter the Number:-9

Enter the Number:-3

Enter the Number:2

Enter the Number:4

Enter the Number:5

Enter the Number:3

Enter the Number:-66

Enter the Number:5

Arranged array is=

3 2 4 5 3 5 -8 -9 -3 -66

BlueJ program on displaying a number in words – as a sentence

2011-11-12T23:03:00.000+05:30

This is a BlueJ program on displaying a number in words. If 234 is entered, the output will be Two Hundred Thirty Four. Here is the program.

import java.io.*;

class Array1

{

int no,i,n, h,t,u;

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

public void take() throws IOException

{

while(true)

{

System.out.println("\nEnter the Number:");

no=Integer.parseInt(br.readLine());

if(no<1000)

break;

}

System.out.print("\nIn words=");

h=no/100;

if(h!=0)

{

switch(h)

{

case 1:

System.out.print(" One Hundred");

break;

case 2:

System.out.print(" Two Hundred");

break;

case 3:

System.out.print(" Three Hundred");

break;

case 4:

System.out.print(" Four Hundred");

break;

case 5:

System.out.print(" Five Hundred");

break;

case 6:

System.out.print(" Six Hundred");

break;

case 7:

System.out.print(" Seven Hundred");

break;

case 8:

System.out.print(" Eight Hundred");

break;

case 9:

System.out.print(" Nine Hundred");

break;

}

no=no%100;

}

t=no/10;

if(t==1)

{

switch(no)

{

case 11:

System.out.print(" Eleven");

break;

case 12:

System.out.print(" Twelve");

break;

case 13:

System.out.print(" Thirteen");

break;

case 14:

System.out.print(" Fourteen");

break;

case 15:

System.out.print(" Fifteen");

break;

case 16:

System.out.print(" Sixteen");

break;

case 17:

System.out.print(" Seventeen");

break;

case 18:

System.out.print(" Eighteen");

break;

case 19:

System.out.print(" Nineteen");

break;

}

else

{

switch(t)

{

case 2:

System.out.print(" Twenty");

break;

case 3:

System.out.print(" Thirty");

break;

case 4:

System.out.print(" Fourty");

break;

case 5:

System.out.print(" Fifty");

break;

case 6:

System.out.print(" Sixty");

break;

case 7:

System.out.print(" Seventy");

break;

case 8:

System.out.print(" Eighty");

break;

case 9:

System.out.print(" Ninety");

break;

}

u=no%10;

switch(u)

{

case 1:

System.out.print(" One");

break;

case 2:

System.out.print(" Two");

break;

case 3:

System.out.print(" Three");

break;

case 4:

System.out.print(" Four");

break;

case 5:

System.out.print(" Five");

break;

case 6:

System.out.print(" Six");

break;

case 7:

System.out.print(" Seven");

break;

case 8:

System.out.print(" Eight");

break;

case 9:

System.out.print(" Nine");

break;

}

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

{

Array1 ob=new Array1();

ob.take();

}

Technical analysis of the BlueJ program

Firstly the entered number is checked whether it is a four digit or more than four digit number. If so, number is re-entered. The number may be of 2 digit. In case of three digit number, hundred position digit is displayed using the word ‘hundred’ after the equivalent word of the digit. Then the tenth position digit is checked and if it is found to be ‘1’, the last two digit number is displayed in equivalent word. In other case, tenth position digit is displayed in word like twenty, thirty and lastly the unit digit equivalent word is displayed.

Sample input and output

Enter the Number:

267

In words= Two Hundred Sixty Seven

Enter the Number:

1234

Enter the Number:

670

In words= Six Hundred Seventy

BlueJ program on circular decoding of a word or sentence

2011-11-06T12:33:00.000+05:30

Suppose the entered word is ‘Abz’, the output will be ‘bCA”. Each character in the word is increased by one character and if it exceeds the upper limit of letters, the starting character will be set. At the end of each character cases is to be changed. The upper case character will be changed to lower case and vice versa.

Here are the codes of the program.

import java.io.*;

class Smith

{

String str;

int i,len;

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

public void take() throws Exception

{

System.out.println("Enter the word:");

str=br.readLine();

len=str.length();

str=move();

str=changeCase();

System.out.println("Modified string="+str);

}

private String move()

{

char ch;

String str1="";

for(i=0;i< len;i++)

{

ch=str.charAt(i);

if((ch>=65 && ch<=90)||(ch>=97 && ch<=122))

ch=(char)(ch+1);

if(ch==91)

ch='A';

if(ch==123)

ch='a';

str1=str1+ch;

}

return str1;

}

private String changeCase()

{

char ch;

String str1="";

for(i=0;i< en;i++)

{

ch=str.charAt(i);

if(ch>=65 && ch< =90)

ch=(char)(ch+32);

else if(ch>=97 && ch< =122)

ch=(char)(ch-32);

str1=str1+ch;

}

return str1;

}

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

{

Smith ob=new Smith();

ob.take();

}

Technical analysis of the circular decoding program

I have used three functions in this program. Function ‘public void take()’ takes the word from user and calls two other functions ‘private String move()’ and ‘private String changeCase()’. The first called function moves each letter by one and if the modified letter crosses the upper range, it is set back to starting letter and the second called function is used to change the case of each letters.

Sample input and output of the circular decoding program

Enter the word:

Abc

Modified string=bCD

Enter the word:

AcX

Modified string=bDy

BlueJ program to generate alternate combination of uppercase letters and its analysis

2011-10-28T09:24:00.000+05:30

Here is the program:

A new advanced Operating System, incorporating the latest hi-tech features has been designed by Opera Computer System. The task of generating copy protection codes to prevent software piracy has been entrusted to the Security Department. The security department has decided to have codes containing a jumbled combination of alternate uppercase letters of the alphabet starting from A upto K (namely among A,C,E,G,I,K). The codes may or may not be in the consecutive series of alphabets.

Develop a program to input a code and its length. At the first instance of an error display “Invalid!” stating the appropriate reason. In case of no error, display the message “Valid!”

Codes of the program:

import java.io.*;

class Sentence

{

String s1="ACEGIK";

boolean bool;

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

public void disp()throws Exception

{

int n;

String sentence;

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

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

System.out.println("Enter the code:");

sentence=br.readLine();

bool=checkLength(sentence,n);

if(!bool)

return;

bool=checkChar(sentence);

if(!bool)

return;

bool=checkSequence(sentence);

if(!bool)

return;

bool=checkRepeat(sentence);

if(!bool)

return;

System.out.println("Valid Input...");

}

private boolean checkLength(String str, int n)

{

boolean b=true;

if(n!=str.length())

{

b=false;

System.out.println("Invalid! String length not the same as specified");

}

else if(n>6)

{

b=false;

System.out.println("Error! Length of string should not exceed 6 characters!");

}

return b;

}

private boolean checkChar(String str)

{

int i,len;

len=str.length();

for (i=0;i< len;i++)

{

if(str.charAt(i)< 65 || str.charAt(i) >90)

break;

}

if(i==len)

return true;

else

{

System.out.println("Invalid! Only upper case characters are permitted.");

return false;

}

private boolean checkSequence(String str)

{

int i,len;

char ch;

len=str.length();

for (i=0;i< len;i++)

{

ch=str.charAt(i);

if(s1.indexOf(ch)< 0)

break;

}

if(i==len)

return true;

else

{

System.out.println("Invalid! Only alternate letters are permitted.");

return false;

}

private boolean checkRepeat(String str)

{

int i,j,len;

char ch;

len=str.length();

for (i=0;i< len-1;i++)

{

ch=str.charAt(i);

for(j=i+1;j< len;j++)

{

if(ch==str.charAt(j))

break;

}

if(j!=len)

break;

}

if(i==len-1)

return true;

else

{

System.out.println("Invalid! Repetition of letters is not permitted.");

return false;

}

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

{

Sentence ob=new Sentence();

ob.disp();

}

Technical analysis of the program

In this program, I have used number of functions to check the validity of the generated code. It is stated in the program that the characters in the code should be within specific letters. The combination of the letters are stored in a string object which will help to check if there is any duplicate letter in the generated code. The function ‘void disp()’ is called first and from this function the entire job of the program is controlled. All the other functions defined in this program are return type and they return ‘true’ if the function finds the generated code is correct in respect of that particular function. These checking functions are called one after another from the body of the function and if any one of them returns ‘false’ means the code is not correct, the program is terminated by using a return statement. If all the functions return true, the last statement of the function ‘void disp()’ will be executed and it prints ‘valid input…’.

Sample input and output

Enter the length:
4

Enter the code:
ABCE
Invalid! Only alternate letters are permitted!

Enter the length:
4

Enter the code:
AcIK

Invalid! Only upper case characters are permitted

Enter the length:
4

Enter the code:
AAKE
Invalid! Repetition of letters is not permitted

Enter the length:
7

Enter the code:
AAKEYYG
Error! Length of string should not exceed 6 characters!

Enter the length:
4

Enter the code:
ACEGI

Invalid! String length not the same as specified

Enter the length:
3

Enter the code:
ACE

Valid Input...

BlueJ program on counting frequency of words in a sentence

2011-10-26T17:39:00.002+05:30

In this program user will enter any sentence and the frequency of each words in the sentence will be displayed.

import java.io.*;

class Sentence

{

int i,j,c;

String sentence,s1,word[]=new String[20];

int x=0;

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

public void disp()throws Exception

{

System.out.println("Enter the sentence:");

sentence=br.readLine();

while(true)

{

i=sentence.indexOf(' ');

if(i<0)

break;

word[x++]=sentence.substring(0,i);

sentence=sentence.substring(i+1);

}

word[x++]=sentence;

for(i=0;i< x-1;i++)

{

for(j=i+1;j< x;j++)

{

if(word[i].compareTo(word[j])>0)

{

s1=word[i];

word[i]=word[j];

word[j]=s1;

}

s1=word[0];

c=1;

for(i=1;i< x;i++)

{

if(s1.equals(word[i]))

c++;

else

{

System.out.println(s1+ " frequence="+c);

c=1;

s1=word[i];

}

System.out.println(s1+ " frequence="+c);

}

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

{

Sentence ob=new Sentence();

ob.disp();

}

Technical analysis of the program

The entered sentence is broken in to words and the words are stored in a string array. The words are then sorted which will help to count frequency of each words. Consecutive words are checked for equality and if match is found a counter is incrementd. When mismatch is found it means that the word is no more in the sentence and the word with its frequency is displayed. The mismatch word is again searched with the remaining words and the same process is repeated.Frequency of the last word is to be displayed from outside the loop as there will be no mismatch with the last word.

Sample input and output

Enter the sentence:

I live in a town which is in Burdwan

Burdwan frequence=1

I frequence=1

a frequence=1

in frequence=2

is frequence=1

live frequence=1

town frequence=1

which frequence=1

Enter the sentence:

Today is Diwali and it is being celebrated in everywhere in India

Diwali frequence=1

India frequence=1

Today frequence=1

and frequence=1

being frequence=1

celebrated frequence=1

everywhere frequence=1

in frequence=2

is frequence=2

it frequence=1