Counter-based while loop in Java - Step-by-Step Execution

Concept Flow - Counter-based while loop

Initialize counter = 0

↓

Check: counter < limit?

No→EXIT

Yes↓

Execute loop body

↓

Update counter = counter + 1

↩Back to Check

Start with a counter, check if it is less than a limit, run the loop body if yes, then increase the counter and repeat until the condition is false.

Execution Sample

Java

int counter = 0;
while (counter < 3) {
    System.out.println(counter);
    counter++;
}

Print numbers 0, 1, 2 by increasing counter until it reaches 3.

Execution Table

Step	counter	Condition (counter < 3)	Action	Output
1	0	true	Print 0, counter++	0
2	1	true	Print 1, counter++	1
3	2	true	Print 2, counter++	2
4	3	false	Exit loop

💡 counter reaches 3, condition 3 < 3 is false, loop stops

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
counter	0	1	2	3	3

Key Moments - 2 Insights

Why does the loop stop when counter equals 3?

Because the condition counter < 3 becomes false at step 4, so the loop exits as shown in the execution_table row 4.

When is the counter variable increased?

The counter is increased after printing the current value inside the loop body, as seen in the Action column of the execution_table rows 1 to 3.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of counter at step 2?

A 2

B 0

C 1

D 3

💡 Hint

Check the 'counter' column in execution_table row 2.

At which step does the loop condition become false?

A Step 4

B Step 2

C Step 3

D Step 1

💡 Hint

Look at the 'Condition' column in execution_table row 4.

If we change the limit from 3 to 5, how many times will the loop run?

A 3 times

B 5 times

C 4 times

D 6 times

💡 Hint

The loop runs while counter < limit, so it runs limit times starting from 0.

Concept Snapshot

Counter-based while loop syntax:
int counter = 0;
while (counter < limit) {
    // loop body
    counter++;
}
Loop runs while condition is true, counter updates each iteration.

Full Transcript

This example shows a counter-based while loop in Java. We start with counter at 0. Each time the loop checks if counter is less than 3. If yes, it prints the counter and then increases it by 1. When counter reaches 3, the condition becomes false and the loop stops. The execution table tracks each step, showing counter values, condition results, actions, and outputs. The variable tracker shows how counter changes after each iteration. Key moments clarify why the loop stops and when the counter increases. The quiz tests understanding of counter values, loop exit step, and effect of changing the limit.