Java Loops Quiz - Multiple Choice Questions (MCQ)

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Loops are an essential part of Java programming, allowing you to repeat a set of instructions multiple times. In this blog post, we present a Java Loops Quiz that consists of 15+ multiple-choice questions (MCQ). This quiz aims to assess your understanding of loop structures in Java, including for loops, while loops, and do-while loops. Let's put your knowledge of Java loops to the test!

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We suggest you try these code snippets in Eclipse IDE and understand how the program works (However, the answer with the explanation given at the end of each question). These questions may ask in interviews, or similar questions may appear in interviews, so prepare yourself.

1. Which loop construct in Java best suits when the number of iterations is known?

a) for loop

b) while loop

c) do-while loop

d) break statement

Answer:

a) for loop

Explanation:

The for loop in Java is used when the number of iterations is known or can be determined beforehand.

2. What is the purpose of the continue statement in a loop?

a) To exit the loop immediately

b) To skip the current iteration and move to the next iteration

c) To terminate the program

d) To execute a specific block of code

Answer:

b) To skip the current iteration and move to the next iteration

Explanation:

The continue statement in Java is used to skip the current iteration of a loop and move to the next iteration.

3. Which loop construct in Java is best suited when the number of iterations is unknown?

a) for loop

b) while loop

c) do-while loop

d) none

Answer:

b) while loop

Explanation:

The while loop in Java is used when the number of iterations is unknown or depends on a certain condition.

4. What is the key difference between a while loop and a do-while loop in Java?

a) The syntax used to define the loop

b) The number of iterations performed

c) The condition check timing

d) The ability to use the break statement

Answer:

c) The condition check timing

Explanation:

The key difference between a while loop and a do-while loop in Java is the timing of the condition check. In a while loop, the condition is checked before the loop body is executed, whereas in a do-while loop, the condition is checked after the loop body is executed.

5. Which loop construct guarantees that the loop body is executed at least once?

a) for loop

b) while loop

c) do-while loop

d) continue statement

Answer:

c) do-while loop

Explanation:

The do-while loop in Java guarantees that the loop body is executed at least once, as the condition is checked after the loop body is executed.

6. What is an infinite loop?

a) A loop that executes only once

b) A loop that never terminates naturally

c) A loop that contains an unreachable code block

d) A loop that uses the continue statement

Answer:

b) A loop that never terminates naturally

Explanation:

An infinite loop in Java is a loop that never terminates naturally unless interrupted externally or using a break statement.

7. Which statement is used to exit a loop prematurely?

a) return statement

b) continue statement

c) break statement

d) exit statement

Answer:

c) break statement

Explanation:

The break statement in Java is used to exit a loop prematurely and continue with the execution of the code outside the loop.

8. Which loop construct is best suited for iterating over an array or a collection?

a) for loop

b) while loop

c) do-while loop

d) continue statement

Answer:

a) for loop

Explanation:

The for loop in Java is best suited for iterating over an array or a collection, as it provides a convenient way to control the iteration using an index or an iterator.

9. Which type of loop is best known for its boolean condition that controls entry to the loop?

a) do-while loop

b) for (traditional)

c) for-each

d) while

Answer:

d) while

Explanation:

A while loop has a condition that returns a boolean that controls the loop. It appears at the beginning and is checked before entering the loop. Therefore, Option D is correct.

A traditional for loop also has a boolean condition that is checked before entering the loop. However, it is best known for having a counter variable, making Option B incorrect.

Option A is incorrect because the boolean condition on a do-while loop is at the end of the loop. Option C is incorrect because there is no condition as part of the loop construct.

10. Which type of loop is best known for using an index or counter?

a) do-while loop

b) for (traditional)

c) for-each

d) while

Answer:

b) for (traditional)

Explanation:

A traditional for loop is best known for having a loop variable counting up or down as the loop progresses. Therefore, Option B is correct.

Options A and D are incorrect because do-while and while loops are known for their boolean conditions.

Option C is incorrect because the for-each loop iterates through without an index.

11. Which of the following can loop through an array without referring to the elements by index?

a) do-while loop

b) for (traditional)

c) for-each

d) while

Answer:

c) for-each

Explanation:

While a traditional for loop often loop through an array, it uses an index to do so, making Option B incorrect.

The for-each loop goes through each element, storing it in a variable. Option C is correct.

12. What is the output of the following code snippet?

int i = 0;
for(i = 0 ; i < 5; i++){
}
System.out.println(i);

a) 5

b) 0

c) 4

d) Compilation Error

Answer:

a) 5

Explanation:

The integer variable i declared before using it in for loop, and can be accessible after for loop execution completes. In for loop, the i value will be incremented until the condition fails ( i < 5) so i value is 5.

13. What is the output of the following program?

public class Test{

     public static void main(String []args){
		int i = 0;
		for(i = 0; i < 10; i++){
			break;
		}
		System.out.println(i);
     }
}

a) 1

b) 0

c) 10

d) 9

Answer:

b) 0

Explanation:

When a break statement is encountered inside a loop, the loop is immediately terminated and the program control resumes at the next statement following the loop.

The Java break statement is used to break the loop or switch statements.

14. What is the output of the following program?

public class Test{

	public static void main(String []args){
		int i = 0;
		for(i = 0; i < 10; i++){
			continue;
		}
		System.out.println(i);
	}
}

a) 10

b) 0

c) Compilation error

d) 9

Answer:

a) 10

Explanation:

Java continue keyword makes for-loop to skip the current iteration and continue with the next iteration. There will be a total of 10 iterations after which the value of variable i becomes 10 and that would make the for loop condition false. So finally the value of variable i is 10 after the loop hence Option A is correct.

15. What is the output of the following program?

public class Test{

	public static void main(String []args){
		for(int i = 0; i < 10; i++){
			if(i % 2 == 0){
				continue;
			}
			System.out.println(i);
		}
	}
}

a) Program will print all even numbers between 0 to 10

b) The program will print all odd numbers between 0 to 10

c) Program gives a compilation error

d) None of the above

Answer:

b) The program will print all odd numbers between 0 to 10

Explanation:

Option B is the correct choice. For loop starts with 0 and goes up to 9 after that the condition becomes false. Inside the loop, if the condition checks if the current value of variable i is divisible by 2 by checking the remainder. If it is 0, the current iteration is skipped using the continue statement. If not, the number is odd (not divisible by 2) and the value is printed.

Conclusion

Congratulations on completing the Java Loops Quiz! We hope it challenged your knowledge and provided valuable insights into loop structures in Java. Loops are fundamental for controlling the flow of your program, and understanding their nuances is crucial for efficient programming.

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Check out 100+ quiz questions: 100+ Quiz Questions to Test Your Java, Spring Boot, Microservices, Hibernate, REST API Skills

Keep practicing, keep learning, and become a master of Java loops!