Enhanced for loop in Java - Step-by-Step Execution

Concept Flow - Enhanced for loop

Start with array or collection

↓

Pick next element

↓

Execute loop body with element

↓

More elements?

No→Exit loop

↩Back to Pick next element

The enhanced for loop goes through each item in a collection or array one by one, running the loop body for each item until all are done.

Execution Sample

Java

int[] nums = {1, 2, 3};
for (int num : nums) {
    System.out.println(num);
}

Prints each number in the array nums one by one using an enhanced for loop.

Execution Table

Iteration	num value	Action	Output
1	1	Print num	1
2	2	Print num	2
3	3	Print num	3
-	-	No more elements, exit loop	-

💡 All elements in nums array have been processed, loop ends.

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
num	-	1	2	3	-

Key Moments - 2 Insights

Why don't we need to use an index variable like in a normal for loop?

The enhanced for loop automatically picks each element in order, so you don't need to manage an index yourself. See execution_table rows 1-3 where num takes each value directly.

Can we modify the array elements using the enhanced for loop variable?

No, the loop variable 'num' is a copy of each element's value, so changing it won't affect the original array. This is shown because 'num' changes but the array stays the same.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'num' at iteration 2?

A 1

B 2

C 3

D None

💡 Hint

Check the 'num value' column in the execution_table at iteration 2.

At which iteration does the enhanced for loop stop running?

A After iteration 3

B After iteration 2

C After iteration 1

D Never stops

💡 Hint

Look at the exit_note and the last iteration row in the execution_table.

If the array nums was empty, what would happen to the loop execution?

A Loop runs once with num = 0

B Loop runs infinitely

C Loop does not run at all

D Error occurs

💡 Hint

Enhanced for loop runs zero times if there are no elements to process, see concept_flow for loop start.

Concept Snapshot

Enhanced for loop syntax:
for (Type var : collection) {
    // use var
}

It automatically loops over each element.
No index needed.
Loop ends after last element.

Full Transcript

The enhanced for loop in Java lets you go through each item in an array or collection easily. You write for (Type var : collection) and inside the loop, var holds the current item. The loop runs once for each element. You don't need to use an index or worry about the length. When all elements are done, the loop stops. For example, if nums is {1, 2, 3}, the loop runs three times with num = 1, then 2, then 3, printing each number. This is simpler and less error-prone than a normal for loop with an index.