ICSE Solved
Paper 2009
Q1. (a) Why is a class
called a factory of objects? [2 marks]
A1. (a) A class is
called a factory of objects because it forms the blueprint from which multiple
objects can be created. It is like a machine in a factory that keeps on
producing objects. We can create as many objects of a class as we wish, with
each object having its own set of instance variables. Each object of a class
will have the same set of attributes and exhibit similar behaviour. Yet, due to
the values of the data members, each is still distinct. Hence, a class is
called a factory of objects.
Q1. (b) State the
difference between a boolean literal and a character literal. [2 marks]
A1. (b)
|
BOOLEAN
LITERAL
|
CHARACTER
LITERAL
|
|
Data type: boolean
|
Data type: char
|
|
Values: true or
false only
|
Values: any char
value
|
|
Value cannot be
converted into an int
|
Value can be
converted into an int
|
|
Space taken up
depends on the implementation, and is not known
|
Space taken up is 2
bytes
|
Q1. (c) What is
the use and syntax of a ternary operator? [2
marks]
A1. (c) The ternary
operator is a short-cut for a commonly used implementation of the if … else
statement. It returns one value if the condition is true, and a second value if
the condition is false.
The ternary operator
is ?:
Syntax:
condition ? value-1 :
value-2
Example:
The code:
int x = 10;
if(x > 5)
System.out.println(1);
else
System.out.println(2);
can be replaced using
the ternary operator with the code:
int x = 10;
System.out.println( (x
> 5) ? 1 : 2 );
Q1. (d) Write one word
answer for the following:
i) A method that
converts a string to a primitive integer data type
ii) The default
initial value of a boolean variable data type
[2 marks]
A1. (d)
i) Integer.parseInt()
ii) false
Q1. (e) State one
similarity and one difference between while and for loop.
[2 marks]
A1. (e)
Similarity: Both loops
are entry-controlled loops (the do..while is exit-controlled, but here we are
asked about while and for, not do..while).
Difference: The for
portion has three sections, and all of them are optional. The sections can be
omitted as long as the semi-colon is mentioned. In the while portion, there is
only one section which is the condition, and it cannot be optional; the
condition of a while loop must be specified.
Q2. (a) Write the
function prototype for the function “sum” that takes an integer variable (x) as
its argument and returns a value of float data type. [2 marks]
A2. (a) float sum(int
x)
Q2. (b) What is the
use of the keyword this? [2 marks]
A2. (b) The keyword
this is used to indicate the current object. The keyword this followed by a
period followed by the name of the instance variable can be used inside a
member method to specifically indicate the instance variable of the calling
object. This is particularly useful when an argument or some local variable in
the same method has the same name as the instance variable.
The keyword this is
also used as a function like this(…) inside a constructor to call an overloaded
constructor of the same class. If used like this, it must be the first
statement of the constructor.
Q2. (c) Why is a class
known as a composite data type? [2 marks]
A2. (c) A class is
known as a composite data type because it can have, as its instance variables,
more than one instance variable, with each of these instance variables being
either a primitive data type or a reference to another class’ object. For
example, a class Car can have String model and intmaxSpeed as its instance
variables.
Q2. (d) Name the
keyword that:
i) is used for
allocating memory to an array
ii) causes the control
to transfer back to the method call
A2. (d)
i) new
ii) return
Q2. (e) Differentiate
between pure and impure functions. [2 marks]
A2. (e)
|
PURE
FUNCTIONS
|
IMPURE
FUNCTIONS
|
|
Produces the same
result (return value) for the same set of parameters, in each call
|
Produces different
result for the same set of parameters, in each call
|
|
The execution of the
function does not result in any side effect (such as the change in state of a
mutable object, or an output to an I/O device.)
|
The execution of the
function may result in an observable side effect.
|
|
Example: Math.sqrt()
|
Example:
Math.random() – returns a random value.
|
|
Example: Math.sin()
|
Example:
System.out.println() since it causes an output to an I/O device (monitor) as
a side effect.
|
Q3. (a) Write an expression
for
(a + b)n
———
√3 + b
[2 marks]
A3. (a) Math.pow(a+b,
n ) / ( Math.sqrt(3) + b )
Q3. (b) The following
is a segment of a program.
x = 1; y = 1;
if(n > 0)
{
x = x + 1;
y = y - 1;
}
What will be the value
of x and y, if n assumes a value (i) 1 (ii) 0?
[2 marks]
A3. (b)
i) x is 2, y is 0
ii) x is 1, y is 1
Q3. (c) Analyze the
following program segment and determine how many times the body of loop will be
executed (show the working).
x = 5; y = 50;
while(x<=y)
{
y=y/x;
System.out.println(y);
}
[2 marks]
A3. (c) The working is
shown in the table below:
|
X
|
Y
|
CONDITION
X<=Y
|
NEW
Y
|
OUTPUT
|
REMARKS
|
|
5
|
50
|
true
|
10
|
10
|
Iteration 1
|
|
5
|
10
|
true
|
2
|
2
|
Iteration 2
|
|
5
|
2
|
false
|
|
|
No 3rd iteration
|
The body of the loop
will be executed 2 times. The output will be:
10
2
Q3. (d) When there are
multiple definitions with the same function name, what makes them different
from each other? [2 marks]
A3. (d) The concept is
called function overloading. Here, the signature of the function makes the functions
different from each other. The signature of a function includes the name of the
function, and the number and data types of the arguments to the function. For
example, the prototypes f(), f(int x), and f(int x, int y), and f(String x) are
all overloaded functions. However, the just by changing the name of the actual
parameter, the signature does not change; for example: f(int x) and f(int y)
are not allowed, since both are f(int).
Q3. (e) Given that
intx[][] = { {2,4,6}, {3,5,7} };
What will be the value
of x[1][0] and x[0][2] ?
[2 marks]
A3. (e)
x[1][0] = 3
x[0][2] = 6
Q3. (f) Give the
output of the following code segment when (i) opn = ‘b’ (ii) opn = ‘x’ (iii)
opn = ‘a’.
switch(opn)
{
case 'a':
System.out.println("Platform
Independent");
break;
case 'b':
System.out.println("Object
Oriented");
case 'c':
System.out.println("Robust
and Secure");
break;
default:
System.out.println("Wrong
Input");
}
[3 marks]
A3. (f)
1. Object Oriented
Robust and Secure
2. Wrong Input
3. Platform Independent
Q3. (g) Consider the
following code and answer the questions that follow:
class academic
{
int x, y;
void access()
{
int a, b;
academic student = new
academic();
System.out.println("Object
created");
}
}
i) What is the object
name of class academic?
ii) Name the class
variables used in the program?
iii) Write the local
variables used in the program.
iv) Give the type of
function used and its name.
[4 marks]
A3. (g)
i) student
ii) there are no class
variables (static). The instance variables used are x and y.
iii) a and b
iv) Name: access()
Type: member function (not
static)
Return value: none
(void)
Q3 (h) Convert the
following segment into an equivalent do loop.
intx,c;
for(x=10,c=20;c>10;c=c-2)
x++;
[3 marks]
A3. (h)
intx,c;
x = 10;
c = 20;
do
{
x++;
c=c-2;
}while(c>10);
Note: At the end, the
value of x = 15, and c = 10
Q4. An electronics
shop has announced the following seasonal discounts on the purchase of certain
items.
|
PURCHASE
AMOUNT
IN RS.
|
DISCOUNT
ON
LAPTOP
|
DISCOUNT
ON
DESKTOP PC
|
|
0 – 25000
|
0.0%
|
5.0%
|
|
25001 – 57000
|
5.0%
|
7.6%
|
|
57001 – 100000
|
7.5%
|
10.0%
|
|
More than 100000
|
10.0%
|
15.0%
|
Write a program based
on the above criteria to input name, address, amount of purchase and type of
purchase (L for Laptop and D for Desktop) by a customer. Compute and print the
net amount to be paid by a customer along with his name and address.
(Hint: discount =
(discount rate/100)* amount of purchase
Net amount = amount of
purchase – discount)
[15 marks]
A4.
importjava.util.*;
class Q4
{
public static void
main(String[] args)
{
// ask user information
Scanner sc = new Scanner( System.in );
String name, address;
int amount;
char type = ' '; //
space
String temp;
System.out.print("Enter
name: ");
name = sc.nextLine();
System.out.print("Enter
address: ");
address =
sc.nextLine();
System.out.print("Enter
amount of purchase: ");
amount = sc.nextInt();
temp = sc.nextLine();
// for trailing new line
// ask the type, if incorrect ask again
do
{
System.out.print("Enter
L for Laptop, D for Desktop: ");
type = sc.nextLine().toUpperCase().charAt(0);
if(
"LD".indexOf(type) < 0 )
System.out.println("Incorrect
type. Try again...");
}while("LD".indexOf(type)
== -1);
// compute discount etc
doublediscountRate =
0.0, discount = 0.0;
doublenetAmount = 0.0;
switch(type)
{
case 'L':
if(amount <= 25000)
discountRate = 0.0;
else if( (amount >=
25001) && (amount <= 57000) )
discountRate = 5.0;
else if( (amount >=
57001) && (amount <= 100000) )
discountRate = 7.5;
else
discountRate = 10.0;
break;
case 'D':
if(amount <= 25000)
discountRate = 5.0;
else if( (amount >=
25001) && (amount <= 57000) )
discountRate = 7.6;
else if( (amount >=
57001) && (amount <= 100000) )
discountRate = 10.0;
else
discountRate = 15.0;
break;
}
discount =
discountRate / 100.0D * amount;
// round to two places of decimal
discount =
Math.round(discount * 100.0);
discount = discount /
100;
netAmount = amount -
discount;
// display the output
System.out.println("BILL");
System.out.println("Customer
name : " + name);
System.out.println("Address : " + address);
System.out.println("Purchase
amount: " + amount);
System.out.println("Purchase
type : " + type);
System.out.println("Discount
% : " + discountRate);
System.out.println("Discount
Amount: " + discount);
System.out.println("Net
amount : " + netAmount);
}
}
2 Sample outputs are
shown below:
Q5. Write a program to
generate a triangle or an inverted triangle till n terms based
upon the user’s choice of triangle to be displayed.
|
EXAMPLE
1
|
EXAMPLE
2
|
|
Input: Type 1 for a
triangle and
type 2 for an inverted triangle
1
Enter the number of terms
5
Output:
1
2 2
3 3 3
4 4 4 4
5 5 5 5 5
|
Input: Type 1 for a
triangle and
type 2 for an inverted triangle
2
Enter the number of terms
6
Output:
6 6 6 6 6 6
5 5 5 5 5
4 4 4 4
3 3 3
2 2
1
|
[15 marks]
A5.
importjava.util.*;
class Q5
{
public static void
main(String[] args)
{
int choice = -1;
int n = 0;
do
{
choice = askChoice();
switch(choice)
{
case 1:
n = askInt("Enter the
number of terms: ");
doTriangle(n);
break;
case 2:
n = askInt("Enter the
number of terms: ");
doInvertedTriangle(n);
break;
case 0:
System.out.println("Exiting
program. Thank you!");
break;
}
}while(choice != 0);
}
// Method to ask 1 for triangle, 2 for
inverted triangle
// 0 for exit
// if wrong entry, ask again
public static
intaskChoice()
{
int x = -1;
do
{
x = askInt("Type 1 for a
triangle and type 2 for an inverted triangle, 0 for exit: ");
if( (x < 0) || (x
> 2) )
System.out.println("Wrong
input. Try again...");
}while( !( (x >= 0)
&& (x <= 2) ) );
return x;
}
// Utility method
// Ask user to enter an integer
// The prompt is passed as a parameter
public static
intaskInt(String prompt)
{
Scanner sc = new Scanner( System.in );
int n;
String temp;
System.out.print(
prompt );
n = sc.nextInt();
temp = sc.nextLine();
// for the trailing newline
return n;
}
// triangle
public static void doTriangle(int
n)
{
inti, j;
for(i=1; i<= n;
i++)
{
for(j=1; j <= i;
j++)
{
System.out.print(i +
" ");
}
System.out.println();
}
}
// inverted triangle
public static void
doInvertedTriangle(int n)
{
inti, j;
for(i=n; i>0; i--)
{
for(j=1; j<=i; j++)
{
System.out.print(i +
" ");
}
System.out.println();
}
}
}
Sample output:
Q6. Write a program to
input a sentence and print the number of characters found in the longest word
of the given sentence.
For example is S =
“India is my country” then the output should be 7.
[15 marks]
A6.
importjava.util.*;
class Q6
{
public static void
main(String[] args)
{
// Ask user to enter a sentence.
Scanner sc = new Scanner( System.in );
System.out.print("Enter
a sentence: ");
String sentence = sc.nextLine();
// Break the sentence into words.
// Use an overloaded parameterized
constructor to use multiple
// word separators.
String[] words = new
String[sentence.length()];
intwordCount = 0;
StringTokenizerst =
new StringTokenizer(sentence, " ,!.?;()");
while(st.hasMoreTokens())
{
words[wordCount++] =
st.nextToken();
}
// Compute the length of the longest
word.
intlongestLength = 0;
inti;
for(i=0;
i<wordCount; i++)
if(words[i].length()
>longestLength)
longestLength =
words[i].length();
// Display the length of the longest
word(s).
System.out.println(
"Length of the longest word(s): " + longestLength);
}
}
Some sample outputs:
Q7. Write a class to
overload a function num_calc() as follows:
i) void
num_calc(intnum, char ch) with one integer argument and one character argument,
computes the square of integer argument if choice ch is ‘s’ otherwise finds its
cube.
ii) voidnum_calc(int
a, int b, char ch) with two integer arguments and one character argument. It
computes the product of integer arguments if ch is ‘p’ else adds the integers.
iii)
voidnum_calc(String s1, String s2) with two string arguments, which prints
whether the strings are equal or not.
[15 marks]
A7.
class Q7
{
// overloaded function #1
voidnum_calc(intnum,
char ch)
{
if(ch == 's')
System.out.println("Square
of " + num + ": " + (num*num));
else
System.out.println("Cube
of " + num + ": " + (num*num*num));
}
// overloaded function #2
voidnum_calc(int a,
int b, char ch)
{
if(ch == 'p')
System.out.println("Product
of " + a + " and " + b + ": " + (a*b));
else
System.out.println("Sum
of " + a + " and " + b + ": " + (a+b));
}
// overloaded function #3
voidnum_calc(String
s1, String s2)
{
if(s1.equals(s2))
System.out.println(s1
+ " and " + s2 + " are equal.");
else
System.out.println(s1
+ " and " + s2 + " are not equal.");
}
//
entry point main method
public static void
main(String[] args)
{
Q7 obj = new Q7();
// calling overloaded function #1
obj.num_calc(3, 's');
obj.num_calc(4, 'c');
// calling overloaded function #2
obj.num_calc(3, 4,
'p');
obj.num_calc(3, 4,
's');
// calling overloaded function #3
obj.num_calc("HELLO",
"HELLO");
obj.num_calc("MELLOW",
"YELLOW");
}
}
Output:
Q8. Write a menu
driven program to access a number from the user and check whether it is a BUZZ
number or to accept any two numbers and to print the GCD of
them.
a) A BUZZ number is
the number which either ends with 7 is is divisible by 7.
b) GCD (Greatest
Common Divisor) of two integers is calculated by continued division method.
Divide the larger number by the smaller; the remainder then divides the
previous divisor. The process is repeated till the remainder is zero. The
divisor then results the GCD.
[15 marks]
A8.
importjava.util.*;
class Q8
{
public static void
main(String[] args)
{
charmenuOption = ' ';
// space
do
{
menuOption =
askMenuOption();
switch(menuOption)
{
case 'B':
doBUZZ();
break;
case 'G':
doGCD();
break;
case 'X':
System.out.println("Exiting
program. Thank you!");
break;
}
}while( menuOption !=
'X' ); // exit when X is entered
}
// ask menu option and return it
// validate that the entry is B, G, or X,
else ask again
public static char
askMenuOption()
{
Scanner sc = new Scanner( System.in );
char option = ' '; //
space
do
{
System.out.print("Enter
B for BUZZ, G for GCD, X to Exit: ");
option =
sc.nextLine().toUpperCase().charAt(0);
if(
"BGX".indexOf(option) < 0 )
System.out.println("Incorrect
option. Try again...");
}while(
"BGX".indexOf(option) < 0 );
return option;
}
// BUZZ number logic
public static void
doBUZZ()
{
int n =
askInt("Enter a number for BUZZ checking: ");
if( ((n%10) == 7) ||
((n%7)==0) )
System.out.println(n +
" is a BUZZ number.");
else
System.out.println(n +
" is not a BUZZ number.");
}
// GCD logic
public static void
doGCD()
{
int n1 =
askInt("Enter number 1 for GCD: ");
int n2 =
askInt("Enter number 2 for GCD: ");
intnr = (n1 > n2) ?
n1 : n2; // larger number
intdr = (n1 > n2) ?
n2 : n1; // smaller number
while( (nr%dr) != 0 )
{
int remainder = nr %
dr;
nr = dr;
dr = remainder;
}
System.out.println("The
GCD of " + n1 + " and " + n2 + " is " + dr);
}
// utility method for prompting user
// and returning an int entered by the user
public static
intaskInt(String prompt)
{
Scanner sc = new Scanner( System.in );
System.out.print(prompt);
int n = sc.nextInt();
String temp = sc.nextLine(); // for the
trailing newline
return n;
}
}
Sample output:
Q9. The annual examination
results of 50 students in a class is tabulated as follows.
|
Roll no.
|
Subject A
|
Subject B
|
Subject C
|
|
………
|
………
|
………
|
………
|
Write a program to
read the data, calculate and display the following:
a) Average mark
obtained by each student.
b) Print the roll number
and average marks of the students whose average mark is above 80.
c) Print the roll
number and average marks of the students whose average mark is below 40.
[15 marks]
A9.
importjava.util.*;
class Q9
{
public static void
main(String[] args)
{
// ask user to enter the data
Scanner sc = new Scanner( System.in );
int N = 10; // use 50
in the exam
int[] rollNo = new
int[N];
int[][] marks = new
int[N][3];
double[] average = new
double[N];
inti, j;
String temp;
for(i=0; i< N; i++)
{
System.out.print("Enter
roll no and 3 marks for student# " + (i+1) + ": ");
rollNo[i] =
sc.nextInt();
for(j=0; j <
marks[i].length; j++)
marks[i][j] =
sc.nextInt();
temp = sc.nextLine();
// for the trailing newline
}
// compute the average
int sum;
for(i=0; i< N; i++)
{
sum = 0;
for(j=0; j <
marks[i].length; j++)
sum += marks[i][j];
average[i] =
(double)sum / (double)marks[i].length;
}
displayAverageOfEach(rollNo,
average);
displayAverageOf80Plus(rollNo,
average);
displayAverageOf40Minus(rollNo,
average);
}
public static void
displayAverageOfEach(int[] rollNo, double[] average)
{
inti;
System.out.println("Average
of each student");
System.out.println("Roll
no. Average");
System.out.println("--------
-------");
for(i=0;
i<rollNo.length; i++)
{
printInt(rollNo[i],
8+1);
printDouble(average[i],
7);
System.out.println();
}
}
public static void
displayAverageOf80Plus(int[] rollNo, double[] average)
{
inti;
System.out.println("Averages
of students with more than 80");
System.out.println("Roll
no. Average");
System.out.println("--------
-------");
for(i=0; i<rollNo.length;
i++)
{
if(average[i] > 80)
{
printInt(rollNo[i],
8+1);
printDouble(average[i],
7);
System.out.println();
}
}
}
public static void
displayAverageOf40Minus(int[] rollNo, double[] average)
{
inti;
System.out.println("Averages
of students with less than 40");
System.out.println("Roll
no. Average");
System.out.println("--------
-------");
for(i=0;
i<rollNo.length; i++)
{
if(average[i] < 40)
{
printInt(rollNo[i],
8+1);
printDouble(average[i],
7);
System.out.println();
}
}
}
public static void
printInt(int n, int width)
{
String s = "" + n;
printStr(s, width);
}
public static void
printDouble(double d, int width)
{
inti =
(int)Math.round(d * 100.0);
String D = "" + i;
String s = D.substring(0, D.length()-2)
+ "." + D.substring(D.length() - 2 );
printStr(s, width);
}
public static void
printStr(String s, int width)
{
System.out.print(s);
int spaces = width -
s.length();
while(spaces > 0)
{
System.out.print("
"); // single space
spaces--;
}
}
}
Sample output with 10
students data:
