Array traversal in Java - Step-by-Step Execution

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Concept Flow - Array traversal

Start at index 0

↓

Check: index < array.length?

No→EXIT

Yes↓

Access array[index

↓

Process element

↓

Increment index

↩Back to Check

Start from the first element, check if the index is within array bounds, process the element, then move to the next index until all elements are visited.

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Execution Sample

Java

int[] arr = {10, 20, 30};
for (int i = 0; i < arr.length; i++) {
    System.out.println(arr[i]);
}

This code prints each element of the array one by one.

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Execution Table

Iteration	i	Condition (i < arr.length)	Action	Output
1	0	0 < 3 = true	Print arr[0] = 10	10
2	1	1 < 3 = true	Print arr[1] = 20	20
3	2	2 < 3 = true	Print arr[2] = 30	30
4	3	3 < 3 = false	Exit loop

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

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Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	0 (initialized)	1	2	3	3
arr[i]	arr[0] = 10	arr[1] = 20	arr[2] = 30	N/A	N/A

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Key Moments - 3 Insights

▶Why does the loop stop when i equals the array length?

▶What happens if we try to access arr[i] when i equals the array length?

▶Why do we start the index i at 0 instead of 1?

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Visual Quiz - 3 Questions

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

A 1

B 2

C 3

D 0

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Concept Snapshot

Array traversal in Java:
- Use a for loop with index i from 0 to i < array.length
- Access elements as array[i]
- Loop stops before i reaches array.length
- Prevents out-of-bounds errors
- Prints or processes each element in order

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Full Transcript

This visual execution trace shows how to traverse an array in Java using a for loop. We start with index i at 0, check if i is less than the array length, then access and print the element at arr[i]. After processing, we increment i by 1 and repeat. The loop stops when i equals the array length, preventing errors. The variable tracker shows how i and arr[i] change each iteration. Key moments clarify why the loop stops at length and why indexing starts at 0. The quiz tests understanding of loop steps and conditions.