Difference between while and do–while in Java - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a while loop that prints numbers from 1 to 3.

Java

int i = 1;
while ([1]) {
    System.out.println(i);
    i++;
}

Drag options to blanks, or click blank then click option'

Ai < 1

Bi <= 3

Ci == 0

Di > 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that never becomes false, causing an infinite loop.

Using a condition that is false at the start, so the loop never runs.

The condition i <= 3 ensures the loop runs while i is 1, 2, or 3.

2fill in blank

medium

Complete the code to create a do-while loop that prints numbers from 1 to 3.

Java

int i = 1;
do {
    System.out.println(i);
    i++;
} while ([1]);

Drag options to blanks, or click blank then click option'

Ai <= 3

Bi == 0

Ci > 3

Di < 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that is false at the start, which still runs once in do-while but may confuse.

Using a condition that never becomes false, causing an infinite loop.

The condition i <= 3 makes the do-while loop run while i is 1, 2, or 3.

3fill in blank

hard

Fix the error in the while loop condition to avoid an infinite loop.

Java

int count = 5;
while ([1]) {
    System.out.println(count);
    count--;
}

Drag options to blanks, or click blank then click option'

Acount < 0

Bcount == 5

Ccount >= 0

Dcount > 5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that never changes to false, causing infinite loop.

Using a condition that is false at the start, so loop never runs.

The condition count >= 0 ensures the loop stops when count becomes -1, preventing infinite looping.

4fill in blank

hard

Fill both blanks to create a while loop that prints even numbers from 2 to 6.

Java

int num = 2;
while ([1]) {
    System.out.println(num);
    num [2] 2;
}

Drag options to blanks, or click blank then click option'

Anum <= 6

Bnum >= 6

C+=

D-=

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong comparison operator that stops the loop too early or never.

Using the wrong operator to change num, causing wrong output.

The condition num <= 6 keeps the loop running until 6. The operator += adds 2 each time to get even numbers.

5fill in blank

hard

Fill all three blanks to create a do-while loop that prints numbers from 1 to 5.

Java

int i = [1];
do {
    System.out.println(i);
    i [2] 1;
} while (i [3] 5);

Drag options to blanks, or click blank then click option'

A0

B+=

C<=

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Starting i at 0 instead of 1.

Using the wrong operator to increase i.

Using a wrong condition that causes infinite loop or no output.

Start i at 1, increase it by 1 each time with +=, and continue while i <= 5.