Core Java Do-While Loop MCQs

Java Do-While Loops are similar to while loops but with a key difference: they execute the loop body at least once before checking the condition. Whether you are just starting or looking to brush up your skills, practicing Java Do-While Loop MCQs can be incredibly beneficial. This exercise will not only help you test your knowledge but also improve your coding skills.

Here is the basic syntax of a do-while loop in Java:

do {
    // Code to execute
} while (condition);

Want to learn more about the do-while loop? Check out the official Java documentation for detailed insights.

Java Do-While Loop MCQs

Question 1:

What is the minimum number of times a 'do-while' loop executes its body?

A 1 time

B Infinite times

C 0 times

D Depends on the condition

View Answer

Correct Answer: A

The 'do-while' loop always executes its body at least once, even if the condition is false.

Question 2:

What will be the output of the following code?

int x = 0;
do {
    System.out.print(x + " ");
    x++;
} while (x < 3);

A 1 2 3

B 0 1 2

C Infinite loop

D 0 1 2 3

View Answer

Correct Answer: B

The loop starts with x=0 and increments it after printing. The condition x < 3 ensures the loop runs until x=3.

Question 3:

Which statement about 'do-while' loops is true?

A The loop executes only if the condition is true.

B The condition is checked before the body is executed.

C The loop body is executed at least once before checking the condition.

D It is identical to a 'while' loop.

View Answer

Correct Answer: C

In a 'do-while' loop, the body is executed once before the condition is checked.

Question 4:

Identify the error in the following code snippet.

do {
    System.out.println("Hello");
} while x < 5;

A 'do' should have curly braces.

B Missing semicolon after 'while'.

C Condition should be enclosed in parentheses.

D No error.

View Answer

Correct Answer: C

The condition in a 'do-while' loop must be enclosed in parentheses.

Question 5:

What will be the output of the following code?

int x = 5;
do {
    System.out.println(x);
    x--;
} while (x > 5);

A No output

B 5 4

C Infinite loop

D 5

View Answer

Correct Answer: D

The loop executes once since the condition (x > 5) is checked after the body.

Question 6:

What will be the output of the following code?

int x = 0;
do {
    System.out.print(x + " ");
    x++;
} while (x <= 0);

A 0 1

B 0

C 0 1 2

D No output

View Answer

Correct Answer: A

The loop executes twice because the condition (x <= 0) is true after the first iteration.

Question 7:

When should you use a 'do-while' loop?

A When the loop should not execute more than once.

B When the loop should execute at least once.

C When the loop should execute only if a condition is true.

D When you want to check the condition first.

View Answer

Correct Answer: B

A 'do-while' loop is useful when the body must execute at least once before the condition is evaluated.

Question 8:

What will happen if the condition in a 'do-while' loop is always true?

A The loop will execute indefinitely.

B The loop will execute once and stop.

C The loop will not execute at all.

D Compilation error.

View Answer

Correct Answer: A

If the condition in a 'do-while' loop is always true, the loop will execute indefinitely unless interrupted.

Question 9:

What will be the output of the following code?

int x = 10;
do {
    x -= 2;
    System.out.print(x + " ");
} while (x > 0);

A 8 6 4 2

B 10 8 6 4 2

C 8 6 4 2 0

D Infinite loop

View Answer

Correct Answer: C

The loop decrements x by 2 each time until x is no longer greater than 0.

Question 10:

Which code snippet will result in a compile-time error?

int x = 0;
do {
    System.out.println(x);
    x++;
} while (x < 5);

int x = 1;
do {
    x--;
} while (x >= 0);

do {
    int x = 5;
    System.out.println(x);
} while (x > 0);

View Answer

Correct Answer: C

Option 1 declares 'x' inside the loop, causing it to be inaccessible in the condition, resulting in a compile-time error.

Question 11:

What will be the output of the following code?

int x = 1;
do {
    System.out.print(x + " ");
    x *= 2;
} while (x < 10);

A Infinite loop

B 1 2 4 8 16

C 2 4 8

D 1 2 4 8

View Answer

Correct Answer: D

The loop multiplies x by 2 on each iteration until x is no longer less than 10. The values printed are 1, 2, 4, and 8.

Question 12:

What is the main difference between 'do-while' and 'while' loops?

A There is no difference; they are functionally identical.

B 'while' checks the condition after executing the loop body.

C 'do-while' checks the condition before executing the loop body.

D 'do-while' executes the loop body at least once.

View Answer

Correct Answer: D

A 'do-while' loop executes the body at least once, while a 'while' loop may not execute the body if the condition is false initially.

Question 13:

What will happen if a 'break' statement is used inside a 'do-while' loop?

A It will cause a compile-time error.

B It will terminate the loop immediately.

C It will skip the current iteration and move to the next one.

D It will have no effect.

View Answer

Correct Answer: B

The 'break' statement terminates the loop immediately, regardless of the loop's condition.

Question 14:

Which of the following code snippets will result in an infinite loop?

int x = 0;
do {
    System.out.println("Hello");
    x++;
} while (x < 5);

int x = 10;
do {
    x--;
} while (x > 0);

int x = 1;
do {
    System.out.println("Hi");
} while (x > 0);

View Answer

Correct Answer: C

Option 1 causes an infinite loop because the condition (x > 0) is always true, as x is never decremented or modified.

Question 15:

What will be the output of the following nested 'do-while' loop?

int i = 1;
do {
    int j = 1;
    do {
        System.out.print(i * j + " ");
        j++;
    } while (j <= 3);
    i++;
} while (i <= 2);

A Infinite loop

B 1 2 3 1 2 3

C 1 2 3 4 5 6

D 1 2 3 2 4 6

View Answer

Correct Answer: D

The outer loop runs for i=1 and i=2, while the inner loop runs for j=1 to j=3. The values printed are the product of i and j: 1 2 3 2 4 6.

Question 16:

What will be the output of the following code?

int x = 0;
do {
    System.out.print(x + " ");
    x += 3;
} while (x < 10);

A 0 3 6 9

B No output

C 0 3 6

D 0 3 6 9 12

View Answer

Correct Answer: A

The loop increments x by 3 on each iteration, stopping when x is no longer less than 10. The values printed are 0, 3, 6, and 9.

Question 17:

Which of the following statements is NOT true about 'do-while' loops?

A The loop body executes at least once.

B The condition is checked after executing the loop body.

C The loop may result in an infinite execution if the condition is always true.

D A 'do-while' loop cannot contain a 'continue' statement.

View Answer

Correct Answer: D

'do-while' loops can contain a 'continue' statement, which skips to the next iteration of the loop.

Question 18:

Which code snippet will produce the output: 5 4 3 2 1?

int x = 5;
do {
    System.out.print(x + " ");
    x--;
} while (x > 0);

int x = 5;
do {
    System.out.print(x + " ");
    x--;
} while (x >= 1);

int x = 5;
do {
    System.out.print(x + " ");
    x++;
} while (x > 0);

View Answer

Correct Answer: A

Option 0 correctly decrements x and prints the values from 5 to 1. Options 1 and 2 have logic issues or conditions that do not match the required output.

Question 19:

What will be the output of the following code?

int x = 10;
do {
    System.out.print(x + " ");
    x -= 3;
} while (x > 2);

A 10 7 4

B 10 7 4 1

C 10 7

D No output

View Answer

Correct Answer: A

The loop decrements x by 3 on each iteration, printing values until x is no longer greater than 2. The output is 10 7 4.

Question 20:

Which of the following best describes the execution flow of a 'do-while' loop?

A Condition â†’ Body (if true)

B Body â†’ Condition â†’ Body (if true)

C Body â†’ Condition (if true)

D Condition â†’ Body â†’ Condition

View Answer

Correct Answer: C

The execution flow of a 'do-while' loop starts with executing the body, followed by evaluating the condition.

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