Loop initialization, condition, update in Java - Step-by-Step Execution

Concept Flow - Loop initialization, condition, update

Initialize loop variable

↓

Check loop condition

No→Exit loop

Yes↓

Execute loop body

↓

Update loop variable

↩Back to Check loop condition

The loop starts by setting a variable, then checks a condition. If true, it runs the loop body, updates the variable, and repeats. If false, it stops.

Execution Sample

Java

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

Prints numbers 0, 1, and 2 by looping with initialization, condition check, and update.

Execution Table

Step	i (loop variable)	Condition (i < 3)	Action	Output
1	0	true	Print i=0	0
2	1	true	Print i=1	1
3	2	true	Print i=2	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 step 4 in the execution_table, so the loop exits.

When is the loop variable i updated?

After executing the loop body at each step, before checking the condition again, as shown in the variable_tracker.

Does the loop body run when the condition is false?

No, the loop body only runs when the condition is true. At step 4, condition is false, so the loop ends without running the body.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of i at step 2?

A 2

B 0

C 1

D 3

💡 Hint

Check the 'i (loop variable)' column at step 2 in the execution_table.

At which step does the loop condition become false?

A Step 3

B Step 4

C Step 1

D Step 2

💡 Hint

Look at the 'Condition (i < 3)' column in the execution_table to find when it is false.

If the update i++ was missing, what would happen to the loop?

A It would run forever because i never changes

B It would stop immediately

C It would print only once

D It would print numbers from 0 to 3

💡 Hint

Think about the variable_tracker and how i changes each step.

Concept Snapshot

for (initialization; condition; update) {
  // loop body
}

1. Initialization runs once at start.
2. Condition checked before each loop; if false, loop ends.
3. Loop body runs only if condition is true.
4. Update runs after each loop body execution.

Full Transcript

This example shows a for loop in Java with initialization, condition, and update. First, the variable i is set to 0. Then the loop checks if i is less than 3. If yes, it 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 step, showing i's value, condition result, action, and output. The variable_tracker shows how i changes after each iteration. Key moments clarify why the loop stops and when i updates. The visual quiz tests understanding of these steps.