Enhanced for loop

Until now, we’ve use out classic counter-based loop to traverse through arrays and lists.

But when you don’t really need the index and just want to use a construct where it says,

“For every item (current) in the collection, use current for something”

This kind of traversal is provided by the enhanced for loop.

Syntax

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for(type current: array/list) {
	use current
}

Example with array

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int[] data = {10, 70, 20, 90};

int total = 0;
for(int item: data) {
	total = total + item;
}

Example with list

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ArrayList<Integer> list = new ArrayList<Integer>();
list.add(10);
list.add(70);
list.add(20);
list.add(90);

int total = 0;
for(int item: list) {
	total = total + item;
}

When should I use the enhanced for loop?

Enhanced for loops are used when you don’t need the index for anything besides accessing the item at that index.

Examples of when enhanced for loop should be used

• Finding the sum of all items in array/list
• Finding the sum of all items (that optionally satisfy some condition(s)) in array/list
• Finding the highest/smallest item in an array/list

Examples when it’s better (IMO) to use a counter-based loop

• Checking if array/list is sorted (because you need to compare an item with the item after it, so you need to access items at index i and i+1).
• Finding the location of the highest/smallest item in an array/list.
• Finding if an array/list contains any duplicates.
• Sorting an array/list.
• Performing binary search over a sorted array/list.