For loop syntax in Java - Step-by-Step Execution

Concept Flow - For loop syntax

Initialize i=0

↓

Check: i < 3?

No→EXIT

Yes↓

Execute body

↓

Update: i = i+1

↩Back to Check

The loop starts by setting i to 0, then checks if i is less than 3. If yes, it runs the loop body, then increases i by 1 and repeats. If no, it stops.

Execution Sample

Java

for (int i = 0; i < 3; i++) {
    System.out.println(i);
}

This code prints numbers 0, 1, and 2 using a for loop.

Execution Table

Iteration	i value	Condition (i < 3)	Action	Output
1	0	true	Print 0, i++	0
2	1	true	Print 1, i++	1
3	2	true	Print 2, i++	2
4	3	false	Exit loop

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

Variable Tracker

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

Key Moments - 3 Insights

Why does the loop stop when i equals 3?

Because the condition i < 3 becomes false at iteration 4 (see execution_table row 4), so the loop exits.

When is the value of i increased?

i is increased after the loop body runs each time (see execution_table Action column), before the next condition check.

What values of i are printed?

Values 0, 1, and 2 are printed during iterations 1 to 3 (see Output column in execution_table).

Visual Quiz - 3 Questions

Look at the execution table, what is the value of i during iteration 2?

A 0

B 2

C 1

D 3

💡 Hint

Check the 'i value' column in execution_table row for iteration 2.

At which iteration does the loop condition become false?

A Iteration 4

B Iteration 3

C Iteration 1

D Never

💡 Hint

Look at the 'Condition (i < 3)' column in execution_table.

If the loop condition changed to i <= 3, how many times would the loop run?

A 3 times

B 4 times

C 2 times

D 5 times

💡 Hint

Think about when i <= 3 is true for i values 0 to 4.

Concept Snapshot

For loop syntax in Java:
for (initialization; condition; update) {
    // code to repeat
}
- Initialization runs once at start.
- Condition checked before each loop; if false, loop ends.
- Update runs after each loop iteration.
- Loop body runs only if condition is true.

Full Transcript

This visual trace shows how a Java for loop works step-by-step. The loop starts by setting i to 0. Then it checks if i is less than 3. If yes, it runs the loop body which prints i, then increases i by 1. This repeats until i reaches 3, when the condition becomes false and the loop stops. The execution table tracks each iteration's i value, condition check, action, and output. The variable tracker shows how i changes from 0 to 3. Key moments clarify why the loop stops at i=3, when i increases, and which values print. The quiz tests understanding of i values, loop exit, and condition changes. The snapshot summarizes the for loop syntax and behavior in Java.