This set of Java Multiple Choice Questions & Answers (MCQs) focuses on “Random Number”.
1. Which class is used to generate random number?
a) java.lang.Object
b) java.util.randomNumber
c) java.util.Random
d) java.util.Object
View Answer
Explanation: java.util.random class is used to generate random numbers in java program.
2. Which method is used to generate boolean random values in java?
a) nextBoolean()
b) randomBoolean()
c) previousBoolean()
d) generateBoolean()
View Answer
Explanation: nextBoolean() method of java.util.Random class is used to generate random numbers.
3. What is the return type of Math.random() method?
a) Integer
b) Double
c) String
d) Boolean
View Answer
Explanation: Math.random() method returns floating point number or precisely a double.
4. Random is a final class?
a) True
b) False
View Answer
Explanation: Random is not a final class and can be extended to implement the algorithm as per requirement.
5. What is the range of numbers returned by Math.random() method?
a) -1.0 to 1.0
b) -1 to 1
c) 0 to 100
d) 0.0 to 1.0
View Answer
Explanation: Math.random() returns only double value greater than or equal to 0.0 and less than 1.0.
6. How many bits are used for generating random numbers?
a) 32
b) 64
c) 48
d) 8
View Answer
Explanation: Random number can accept 64 bits but it only uses 48 bits for generating random numbers.
7. What would be the output of following code snippet?
int a = random.nextInt(15) + 1;
a) Random number between 1 to 15, including 1 and 15
b) Random number between 1 to 15, excluding 15
c) Random number between 1 to 15, excluding 1
d) Random number between 1 to 15, excluding 1 and 15
View Answer
Explanation: random.nextInt(15) + 1; returns random numbers between 1 to 15 including 1 and 15.
8. What would be the output of following code snippet?
int a = random.nextInt(7) + 4;
a) Random number between 4 to 7, including 4 and 7
b) Random number between 4 to 7, excluding 4 and 7
c) Random number between 4 to 10, excluding 4 and 10
d) Random number between 4 to 10, including 4 and 10
View Answer
Explanation: random.nextInd(7) + 4; returns random numbers between 4 to 10 including 4 and 10. it follows “nextInt(max – min +1) + min” formula.
9. Math.random() guarantees uniqueness?
a) True
b) False
View Answer
Explanation: Math.random() doesn’t guarantee uniqueness. To guarantee uniqueness we must store the generated value in the database and compare against already generated values.
10. What is the signature of Math.random() method?
a) public static double random()
b) public void double random()
c) public static int random()
d) public void int random()
View Answer
Explanation: public static double random() is the utility method provided by Math class which returns double.
Sanfoundry Global Education & Learning Series – Java Programming Language.
