Important Java questions and programs for ICSE class 9th and 10th board exams
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Important questions of ICSE class 10th board exam Section-A
Question::
a) What is Inheritance ? [2]
Ans. Inheritance is the process by which one class extends another class to inherit the variables and functions and add any additional variables and methods.
b) Name the operators listed below [2]
i) < ii) ++ iii) && iv) ?:
Ans. i) Less than comparison operator
ii) Increment operator
iii) And logical operator
iv) Ternary operator
c) State the number of bytes occupied by char and int data types.[2]
Ans. char occupies two bytes and int occupied 4 bytes.
d) Write one difference between / and % operator. [2]
Ans. / is division operator while % is modulus operator which gives the remainder on dividing two numbers.
Question::
a) Name of the following: [2]
i) A keyword used to call a package in the program.
ii) Any one reference data types.
Ans. i) import
ii) String
b) What are the two ways of invoking functions? [2]
Ans. Call by value and call by reference
c) State the data type and value of res after the following is executed : [2]
1 char ch = 't';
2 res = Character.toUpperCase(ch);
Ans.Data type of res is char and value is T
d) Give the output of the following program segment and also mention the number of times the loop is executed: [2]
int a,b;
for(a=6,b=4;a<=24;a=a+6)
{
if(a%b==0)
break;
}
System.out.println(a);
Ans.
Loop initialization: a = 6, b = 4
First iteration:
Condition check: a <= 24 --- 6 <= 24 ---- true
Loop is executed for the first time
Loop execution: a % b = 6 % 4 = 2 != 0 Hence, break is not executed
Loop increment operator: a = 1 + 6 --- a = 6 + 6 = 12
Second iteration:
Condition check: a <= 24 --- 12 <= 24 ---- true
Loop is executed for the second time
Loop execution: a % b = 12 % 4 = 0 = 0 Hence, break is executed
System.out.println(a); --- 12
Output is 12 and loop is executed two times
Question::
a) Write a Java expression for the following : [2]
ax5 + bx3 + c
Ans. a * Math.pow(x, 5) + b * Math.pow(x, 3) + c
b) Why is an object called an instance of a class? [2]
Ans. An object is called an instance of a class as every object created from a class gets its own instances of the variables defined in the class.Multiple objects can be created from the same class.
d) Convert following do-while loop into for loop. [2]
int i=1;
int d=5;
do{
d=d*2
System.out.println(d);
i++;
}while(i<=5);
Ans.
for(int i=5, d=5; i<=5; i++) {
d = d * 2;
System.out.println(d);
}
c) Differentiate between constructor and function. [2]
Ans. The constructor of a class is invoked automatically during object creation while a function is invoked manually after object creation.
A constructor is invoked only once while a function can be invoked multiple times.
A constructor has the same name as the class in which it is defined while a function can have any name.
g) What are the values stored in variables r1 and r2: [2]
i) double r1 = Math.abs(Math.min(-2.83,-5.83));
ii) double r2 = Math.sqrt(Math.floor(16.3));
Ans. i) double r1 = Math.abs(Math.min(-2.83,-5.83));
= Math.abs(-5.83)
= 5.83
ii) double r2 = Math.sqrt(Math.floor(16.3));
= Math.sqrt(16)
= 4.0
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