Java For-Each Loop

When a ticket checker walks through a coach, they don't think "seat number 0, seat number 1, seat number 2". They just visit each passenger in turn. Java's for-each loop (officially the enhanced for loop) works the same way: it hands you every element of an array or a list, one at a time, with no counter to manage.

Visit Each Element

public class Marks {
    public static void main(String[] args) {
        int[] marks = {78, 92, 86, 64};
        for (int mark : marks) {
            System.out.println("Mark: " + mark);
        }
    }
}

Mark: 78
Mark: 92
Mark: 86
Mark: 64

Read line 4 as "for each int mark in marks". In each round, mark holds the next element, from first to last.

Totals and Searches

public class Cart {
    public static void main(String[] args) {
        String[] items = {"Rice", "Dal", "Oil"};
        int[] prices = {340, 165, 190};
        int total = 0;
        for (int price : prices) {
            total += price;
        }
        for (String item : items) {
            System.out.print(item + " ");
        }
        System.out.println();
        System.out.println("Total: Rs. " + total);
    }
}

Rice Dal Oil
Total: Rs. 695

The first loop adds up the prices; the second prints each item name. Neither needs to know how many elements there are.

Try it yourself: add a fourth item and price. Do you need to change either loop?

For-Each vs Counting for

Works on Lists Too

for-each works on arrays and on any collection, such as an ArrayList (covered with collections, later in the course):

import java.util.List;
 
public class Stops {
    public static void main(String[] args) {
        List<String> stops = List.of("Vijayawada", "Warangal", "Kazipet");
        int count = 0;
        for (String stop : stops) {
            count++;
            System.out.println(count + ". " + stop);
        }
    }
}

1. Vijayawada
2. Warangal
3. Kazipet

When you need a number for each element, a small counter like count works without switching to a counting loop.

Common Mistakes

Expecting to change the array through the loop variable. It's a copy; see the warning above.

Removing items from a list inside a for-each. It throws ConcurrentModificationException. The collections lessons, later in the course, show the safe ways.

Using the wrong type. for (String s : marks) on an int[] doesn't compile.

Practice

1. Easy: Print the largest value in {45, 82, 17, 93, 60} using a for-each loop.
2. Harder: Count how many marks in an array are 35 or above (passes) and how many are below, using one for-each loop.

Key Takeaways