Counter-based while loop in Java - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple counter-based while loop

What is the output of the following Java code?

Java

int count = 1;
while (count <= 3) {
    System.out.print(count + " ");
    count++;
}

A 1 2 3

B 0 1 2 3

C 1 2 3 4

D 1 2

💡 Hint

Think about how the counter changes and when the loop stops.

The loop starts at 1 and runs while count is less than or equal to 3. It prints 1, then 2, then 3, then stops.

❓ Predict Output

intermediate

Counting down with a while loop

What will this Java code print?

Java

int count = 5;
while (count > 2) {
    System.out.print(count + " ");
    count--;
}

A 5 4 3 2

B 5 4 3

C 5 4 3 2 1

D 4 3 2

💡 Hint

Look at the condition and how the counter decreases.

The loop runs while count is greater than 2, so it prints 5, 4, and 3, then stops before printing 2.

❓ Predict Output

advanced

Sum of numbers using a while loop

What is the value of sum after this code runs?

Java

int count = 1;
int sum = 0;
while (count <= 4) {
    sum += count;
    count++;
}
System.out.println(sum);

A 10

B 9

C 11

D 0

💡 Hint

Add numbers 1 through 4 together.

The loop adds 1 + 2 + 3 + 4 = 10 to sum.

❓ Predict Output

advanced

Loop with incorrect counter update

What happens when this code runs?

Java

int count = 1;
while (count <= 3) {
    System.out.print(count + " ");
    // Missing count++ here
}

A Prints nothing

B Prints 1 2 3 and stops

C Syntax error due to missing increment

D Infinite loop printing 1 repeatedly

💡 Hint

What happens if the counter never changes inside the loop?

Without increasing count, the condition is always true and the loop never ends, printing 1 forever.

🧠 Conceptual

expert

Number of iterations in a counter-based while loop

How many times will the loop body execute in this code?

Java

int count = 2;
while (count < 10) {
    count += 3;
}

A 4

B 6

C 3

D 5

💡 Hint

Trace the values: start with count=2, add 3 each time until the condition fails.

count=2 (<10), body executes (count=5); 5<10, body (count=8); 8<10, body (count=11); 11<10 false, stop. Executes 3 times.