ICSE Class 10 - Computer Application Important Questions & Answers (2 Marks)

02 (Two) Marks Questions 

Question 1- Give one example each of a primitive data type and a composite data type.

Ans. Primitive Data Types – byte, short, int, long, float, double, char, boolean

Composite Data Type – Class, Array, Interface

Question 2- Give one point of difference between unary and binary operators. 

Ans. A unary operator requires a single operand whereas a binary operator requires two operands.

Examples of Unary Operators – Increment ( ++ ) and Decrement ( — ) Operators

Examples of Binary Operators – +, -, *, /, %

Question 3- Differentiate between call by value or pass by value and call by reference or pass by reference.

Ans. In call by value, a copy of the data item is passed to the method which is called whereas in call by reference, a reference to the original data item is passed. No copy is made. Primitive types are passed by value whereas reference types are passed by reference.

Question 4- Write a Java expression for (under root of 2as+u2)

Ans. Math.sqrt ( 2 * a * s + Math.pow ( u, 2 ) )

( or )

Math.sqrt ( 2 * a * s + u * u )

Question 5- Name the types of error (syntax, runtime or logical error) in each case given below:

(i) Division by a variable that contains a value of zero.

(ii) Multiplication operator used when the operation should be division.

(iii) Missing semicolon. 

Ans.

(i) Runtime Error

(ii) Logical Error

(iii) Syntax Error

Question 6- Create a class with one integer instance variable. Initialize the variable using:

(i) default constructor

(ii) parameterized constructor. 

Ans.

public class Integer 

{

    int x;

    public Integer() {

        x = 0;

    }

    public Integer(int num) {

        x = num;

    }

}

Question 7- Complete the code below to create an object of Scanner class.

Scanner sc = ___________ Scanner( ___________ )

Ans. Scanner sc = new Scanner ( System.in );

Question 8- What is an array? Write a statement to declare an integer array of 10 elements.

Ans. An array is a reference data used to hold a set of data of the same data type. The following statement declares an integer array of 10 elements -

int arr[] = new int[10];

Question 9- Name the search or sort algorithm that:

(i) Makes several passes through the array, selecting the next smallest item in the array each time and placing it where it belongs in the array.

(ii) At each stage, compares the sought key value with the key value of the middle element of the array.

Ans. (i) Selection Sort

(ii) Binary Search

Question 10- Differentiate between public and private modifiers for members of a class.

Ans. Variables and Methods whwith the public access modie the class also.

Question 11- Question - What are the values of x and y when the following statements are executed?  

int a = 63, b = 36;

boolean x = (a < b ) ? true : false; int y= (a > b ) ? a : b ;

Ans. x = false

y = 63

Question 12- State the values of n and ch

char c = 'A':

int n = c + 1;

Ans. The ASCII value for ‘A’ is 65. Therefore, n will be 66.

Question 13- What will be the result stored in x after evaluating the following expression?

int x=4;

x += (x++) + (++x) + x;

Ans. x = x + (x++) + (++x) + x
x = 4 + 4 + 6 + 6
x = 20

Question 14- Give the output of the following program segment:

double x = 2.9, y = 2.5;

System.out.println(Math.min(Math.floor(x), y));

System.out.println(Math.max(Math.ceil(x), y));

Ans. 
2.0
3.0
Explanation : Math.min(Math.floor(x), y) = Math.min ( 2.0, 2.5 ) = 2.0
Math.max(Math.ceil(x), y)) = Math.max ( 3.0, 2.5 ) = 3.0

Question 15- State the output of the following program segment.

String s = "Examination";
int n = s.length();
System.out.println(s.startsWith(s.substring(5, n)));
System.out.println(s.charAt(2) == s.charAt(6));

Ans.
false
true
Explanation : n = 11
s.startsWith(s.substring(5, n)) = s.startsWith ( “nation” ) = false
( s.charAt(2) == s.charAt(6) ) = ( ‘a’== ‘a’ ) = true

Question 16- State the method that:
(i) Converts a string to a primitive float data type
(ii) Determines if the specified character is an uppercase character
Ans. (i) Float.parseFloat(String)
(ii) Character.isUpperCase(char)

Question 17- State the data type and values of a and b after the following segment is executed.

String s1 = "Computer", s2 = "Applications";

a = (s1.compareTo(s2));

b = (s1.equals(s2));

Ans. Data type of a is int and b is boolean.
ASCII value of ‘C’ is 67 and ‘A’ is 65. So compare gives 67-65 = 2.
Therefore a = 2
b = false

Question 18- What will the following code output?

String s = "malayalam";

System.out.println(s.indexOf('m'));

System.out.println(s.lastIndexOf('m'));

Ans.
0
8

Question 19- Rewrite the following program segment using while instead of for statement

int f = 1, i;

for (i = 1; i <= 5; i++) 

{

    f *= i;

    System.out.println(f);

}

Ans.

int f = 1, i = 1;
while (i <= 5) 
{
    f *= i;
    System.out.println(f);
    i++;

}

Question 20- In the program given below, state the name and the value of the
(i) method argument or argument variable
(ii) class variable
(iii) local variable
(iv) instance variable

class myClass {

static int x = 7;
int y = 2;

public static void main(String args[]) {
myClass obj = new myClass();
System.out.println(x);
obj.sampleMethod(5);
int a = 6;
System.out.println(a);
}

void sampleMethod(int n) {
System.out.println(n);
System.out.println(y);
}
}

Ans. (i) name = n value =5
(ii) name = y value = 7
(iii) name = a value = 6
(iv) name = obj value = new MyClass()

Question 21- What is
meant by precedence of operators?

Ans. Precedence of operators refers to the order in which
the operators are applied to the operands in an expression. For example, * has
higher precedence than +. So, the expression 8 + 2 * 5 will evaluate to 8 + 10
= 18





Question 22- What is a
literal?

Ans. A literal is a constant data item. There are different
literals like integer literals, floating point literals and character literals.





Question
23- State the Java concept that
is implemented through: 

i) a super
class and a subclass.

ii) the act
of representing essential features without including background details.

Ans. i) Inheritance

ii) Abstraction.







Question
24- Give a difference between
constructor and method.

Ans. i)A constructor has no return type which a method has a
return type.

ii) The name of the constructor should be the same as that of
the class while the name of a method can be any valid identifier.

iii) A constructor is automatically called upon object
creation while methods are invoked explicitly.





Question
25- What are the types of
casting shown by the following examples?

i) double x
=15.2;

int y =(int)
x;

ii) int x
=12;

long y = x;

Ans. i) Explicit casting

ii) Implicit casting





Question
26- Name any two wrapper
classes.

Ans. Byte, Short, Integer, Long, Float, Double, Boolean,
Character





Question
27- What is the difference
between break and continue statements when they occur in a loop.

Ans. The break statement terminates the loop while the
continue statements current iteration of the loop to be skipped and continues
with the next iteration.





Question
28- Write statements to show
how finding the length of a character array and char[] differs from finding the
length of a String object str.

Ans. The length of a character array is found by accessing
the length attribute of the array as shown below:

char[] array = new char[7];

int lengthOfCharArray = array.length;

The length of a String object is found by invoking the
length() method which returns the length as an int.

String str = “java”;

int lengthOfString = str.length();





Question
29- Name the Java keyword that:

(i)
indicates a method has no return type.

(ii) stores
the address of the currently calling object.

Ans. i) void

ii) this





Question
30- What is an exception?

Ans. An exception is an unforeseen situation that occurs
during the execution of a program. In simpler words, they are the errors that
occur during the execution of a program. The JRE throws an Exception object to
indicate an exception which contains the information related to that exception.





Question
31- Write Java statement to
create an object mp4 of class digital.

Ans. digital mp4 = new digital();





Question
32- State the values stored in
variables str1 and str2


String s1 = "good";


String s2="world matters";


String str1 = s2.substring(5).replace('t','n');


String str2 = s1.concat(str1);


Ans. s2.substring(5)
gives ” matters”. When ‘t’ is replaced with ‘n’, we get ” manners”.

“good” when concatenated with ” manners” gives “good manners”.

So, str1 = ” manners” and str2 = “good manners”.







Question
33- What does a class encapsulate?

Ans. A class encapsulated the data (instance variables) and
methods.





Question
34- Rewrite the following
program segment using the if..else statement.

comm =(sale>15000)?sale*5/100:0;

Ans.

if ( sale > 15000 ) {

   comm = sale * 5 / 100;

} else {

   comm = 0;

}




Question
35- How many times will the
following loop execute? What value will be returned?

int x = 2, y = 50;

do{

++x;

y-=x++;

}while(x<=10);

return y;


Ans. In the first
iteration, ++x will change x from 2 to 3. y-=x++ will increase x to 4. And y
becomes 50-3=47.

In the second iteration, ++x will change x from 4 to 5.
y-=x++ will increase x to 6. And y becomes 47-5=42.

In the third iteration, ++x will change x from 6 to 7. y-=x++
will increase x to 8. And y becomes 42-7=35.

In the fourth iteration, ++x will change x from 8 to 9.
y-=x++ will increase x to 10. And y becomes 35-9=26.

In the fifth iteration, ++x will change x from 10 to 11.
y-=x++ will increase x to 12. And y becomes 26-11=15.

Now the condition x<=10 fails.

So, the loop executes five times and the value of y that will
be returned is 15.





Question
36- What is the data type that
the following library functions return?

i)
isWhitespace(char ch)

ii)
Math.random()

Ans. i) boolean

ii) double





Question
37- Write a Java expression for
ut + ½ ft2

Ans. u * t + 0.5 * f * Math.pow ( t, 2)





Question
38- If int n[] ={1, 2, 3, 5, 7,
9, 13, 16} what are the values of x and y?

x=Math.pow(n[4],n[2]);

y=Math.sqrt(n[5]+[7]);


Ans.


n[4] is 7 and n[2] is 3. So, Math.pow(7,3) is
343.0.

n[5] is 9 and n[7] is 16. So Math.sqrt(9+16) will give 5.0.

Note that pow() and sqrt() return double values and not int
values.


Question
39- What is the final value of
ctr after the iteration process given below, executes?

int ctr=0;

for(int i=1;i&lt;=5;i++)

for(int j=1;j&lt;=5;j+=2)

++ctr;


Ans.


Outer loop runs five times. For each iteration
of the outer loop, the inner loop runs 3 times. So, the statement ++ctr
executes 5*3=15 times and so the value of ctr will be 15.





Question 40- Name the methods of Scanner class that:

i) is used
to input an integer data from standard input stream.

ii) is used
to input a string data from standard input stream.

Ans. i) scanner.nextInt()

ii) scanner.next() 





Question 41. What is the difference between an object and a class? 

Ans. 1. A class is a blueprint or a prototype of a
real world object. It contains instance variables and methods whereas an object
is an instance of a class.

2. A class exists in the memory of a computer while an object does not.

3. There will be only one copy of a class whereas multiple objects can be
instantiated from the same class.

Question 42. What does the token ‘keyword’ refer to in the
context of Java? Give an example for keyword. 

Ans. Keywords are reserved words which convey
special meanings to the compiler and cannot be used as identifiers. Example of
keywords : class, public, void, int

Question 43. State the difference between entry controlled
loop and exit controlled loop. 

Ans. In an entry controlled loop, the loop
condition is checked before executing the body of the loop. While loop and for
loop are the entry controlled loops in Java.

In exit controlled loops, the loop condition is checked after executing the
body of the loop. do-while loop is the exit controlled loop in Java.

Question 44. What are the two ways of invoking functions? 

Ans. If the function is static, it can be invoked
by using the class name. If the function is non-static, an object of that class
should be created and the function should be invoked using that object.

Question 45. What is difference between / and % operator? 

Ans. / is the division operator whereas % is the
modulo (remainder) operator. a / b gives the result obtained on diving a by b
whereas a % b gives the remainder obtained on diving a by b.

Question 46. State the total size in bytes, of the arrays
a [4] of char data type and p [4] of float data type. 

Ans. char is two bytes. So a[4] will be 2*4=8
bytes.

float is 4 bytes. So p[4] will be 4*4=16 bytes.

Question 47.  (i)
Name the package that contains Scanner class.

(ii) Which unit of the class gets called, when the object of the class is
created? 

Ans. (i) java.util

(ii) Constructor

Question 48. Give the output of the following: 

String n = “Computer Knowledge”;

String m = “Computer Applications”;

System.out.println(n.substring (0,8). concat
(m.substring(9)));

System.out.println(n.endsWith(“e”));

Ans. n.substring(0,8)
gives “Computer”. m.substring(9) gives “Applications”. These two on
concatenation gives “ComputerApplications”. n ends with “e”. So, it gives true.

The output is:

ComputerApplications

true 

Question 49.  (d)
Write the output of the following: 

(i) System.out.println (Character.isUpperCase(‘R’));

(ii) System.out.println(Character.toUpperCase(‘j’));

Ans. (i) true

(ii) J

Question 50.  (e)
What is the role of keyword void in declaring functions? 

Ans. void indicates that the function doesn’t
return any value.

Question 51. Analyse the following program segment and
determine how many times the loop will be executed and what will be the output
of the program segment ?

int p = 200;

while(true)

{

if (p<100)

break;

p=p-20;

}

System.out.println(p);

Ans.p
values changes as follows : 200, 180, 160, 140, 120, 100, 80. So, the loop
executes six times and value of p is 80.

Question 52. What will be the output of the following
code?

(i)

int k = 5, j = 9;

k += k++ – ++j + k;

System.out.println("k= " +k);

System.out.println("j= " +j);

Ans.

k=6

j = 10

Explanation:

k += k++ – ++j + k

k = k + k++ – ++j + k

k = 5 + 5 – 10 + 6

k = 6

j = 10 as it has been incremented in the ++j operation.

Question 53. Output the given code

double b = -15.6;

double a = Math.rint (Math.abs (b));

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

Ans.

a = 16.0

Maths.abs(-15.6) will give 15.6 and Math.rint(15.6) gives
16.0.

Question 54.  Explain
the concept of constructor overloading with an example . 

Ans. A class can have more than one constructor
provided that the signatures differ. This is known as constructor overloading.

Example:

class Age 

{

    int age;

    public Age() 

    {

      age = -1;

    }



    public Age(int
age) 

    {

        this.age =
age;

    }

} 

Question 55. Give the prototype of a function search
which receives a sentence sentnc and a word wrd and returns 1 or 0 ? [2]

Ans.

public boolean function ( sentence sentnc, word wrd )

or

public int function ( sentence sentnc, word wrd )

Question 56. Write
an expression in Java for z = (5×3 + 2y ) / ( x + y) [2]

Ans.

z = ( 5 * Math.pow ( x, 3 ) + 2 * y ) / ( x + y )

Question 57. Write a statement each to perform the
following task on a string: 

(i) Find and display the position of the last space in a string s.

(ii) Convert a number stored in a string variable x to double data type

Ans. (i) System.out.println(s.lastIndexOf(”
“);

(ii) Double.parseDouble(x)

Question 58.  Name
the keyword that: 

(i) informs that an error has occurred in an input/output operation.

(ii) distinguishes between instance variable and class variables.

Ans. (i) throw

(ii) static

Question 59. What are library classes ? Give an example. 

Ans. Library classes are the predefined classes
which are a part of java API. Ex: String, Scanner








































































































































Question 60. Write one difference between Linear Search
and Binary Search . 

Ans. Linear search can be used with both
sorted and unsorted arrays. Binary search can be used only with sorted arrays.



Question 61- Define the term Byte Code.

Ans. The Java compiler compiles the source programs into an intermediate code called the Java Byte Code which is interpreted by the Java Virtual Machine (JVM)



Question 62- What do you understand by type conversion? 

Ans. Type conversion or casting is the conversion of the data type of a literal from one type to another. There are tow types of types of casting – implicit casting and explicit casting.



Question 63- Name two jump statements and their use. 

Ans. break and continue are the two jump statements in Java. break is used to force early termination of a loop. continue is used to move to the next iteration of the loop while skipping the remaining code in the current iteration.



Question 64- What is Exception ? Name two Exception Handling Blocks. 

Ans. An Exception is an error which occurs during the execution of a program. The exception handling blocks are try, catch and finally.



Question 65- Write two advantages of using functions in a program. 

Ans. i) Function make code reusable.

ii) Functions improve modularity and facilitate easy debugging.



Question 66- State the purpose and return data type of the following String functions: 

(i) indexOf ( )

(ii) compareTo ( )

Ans. i) indexOf() returns the index of the character or String passed as the parameter in the string on which is invoked.

Return type is int.

ii) compareTo() lexicographically compares the String passed as an argument to the String on which it is invoked.

Return type is int.



Question 67- What is the result stored in x, after evaluating the following expression 

int x = 5;

x = x++ * 2 + 3 * –x;

Ans. x = 5 * 2 + 3 * -6

x = 10 – 18

x = -8



Question 68- Differentiate between static and non-static data members. 

Ans. i) static variables belong to the class and all object share a single instance of the static variables. Non static varaiables belong to the objects. Each object has a copy of these members.

ii) static functions can access only static data members. Non static function can access both static and non static data members.



Question 69- Write the difference between length and length() functions. 

Ans. length is a property of an array which gives the size of the array. length() is a function of the String class which returns the size of the String.



Question 70- Differentiate between private and protected visibility modifiers. 

Ans. private members are accessible only in the class in which they have been defined. protected members are accessible in the class in which they have been defined as well in the sub classes of that class.





Question 71- What do you understand by data abstraction? Explain with an example.

Ans. Abstraction refers to representing the essential features of a system without considering all the details. Example: When we drive a car, we concentrate on how to drive it without bothering ourselves on how the engine works and other things.



Question 72- What will be the output of the following code?

int m=2;

int n=15;

for(int i = 1; i<5; i++);

m++; –-n;

System.out.println("m=" +m);

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

Ans.



m=3

n=14

Note that there is a semicolon at the end of the loop. So, it is an empty loop and does’t affect the values of m and n.



Question 73- What will be the output of the following code?



char x = 'A' ; int m;

m=(x=='a') ? 'A' : ‘a’;

System.out.println("m="+m);

Ans.



m=97



Question 74- Analyse the following program segment and determine how many times the loop will be executed and what will be the output of the program segment.



 int k=1, i=2;

while (++i<6)

k*=i;

System.out.println(k);

Ans. Following are the iterations of the loop



3 < 6 ---- k = 1 * 3 = 3

4 < 6 ---- k = 3 * 4 = 12

5 < 6 ---- k = 12 * 5 = 60

6 < 6 ---- false

The loop will run three times and output is 60



60



Question 75- Give the prototype of a function check which receives a character ch and an integer n and returns true or false.

Ans.



public boolean check(char ch, int n)



Question 76- State two features of a constructor.

Ans. i) A constructor has the same name as that of a class.

ii) A constructor does not have any return type.

iii) A constructor is automatically called during object creation.



Question 77- Write a statement each to perform the following task on a string:

Extract the second last character of a word stored in the variable wd.

Ans.



char ch = wd.charAt(wd.length()-2);



Question 78- Check if the second character of a string str is in uppercase.

Ans.



boolean result = Character.isUpperCase(str.charAt(1));



Question 79- What will the following functions return when executed?

(i) Math.max(-17, -19)

(ii) Math.ceil(7.8)

Ans. i) -17

ii) 8.0



Question 80- (i) Why is an object called an instance of a class?

(ii) What is the use of the keyword import?

Ans. i) An object is called an instance of a class because the objects contains a copy of all the instance variables of the class.



ii) The import keyword is used to import classes from external packages.