Java Enhanced For-Each Loop: Iterating Arrays and Collections

Introduced in Java 5, the Enhanced For-Each Loop offers a streamlined, error-proof syntax designed specifically to traverse arrays and any object implementing the java.lang.Iterable interface (such as ArrayList, HashSet, LinkedList).

Syntax Comparison: Traditional For vs. Enhanced For

// Traditional For Loop (Requires manual index counter & bounds check):
for (int i = 0; i < array.length; i++) {
    System.out.println(array[i]);
}

// Enhanced For-Each Loop (Eliminates off-by-one errors & boilerplate):
for (ElementType variableName : arrayOrCollection) {
    System.out.println(variableName);
}

Code Example: Traversing Arrays & Collections

import java.util.List;
import java.util.ArrayList;

public class ForEachDemo {
    public static void main(String[] args) {
        // 1. Iterating an Array of Strings
        String[] technologies = { "Java", "Spring Boot", "Docker", "Kubernetes" };
        System.out.println("--- Array Traversal ---");
        for (String tech : technologies) {
            System.out.println("Tech: " + tech);
        }

        // 2. Iterating a Collection (List)
        List<Integer> scores = new ArrayList<>();
        scores.add(88);
        scores.add(94);
        scores.add(76);

        int total = 0;
        for (int score : scores) { // Autounboxing from Integer to int
            total += score;
        }
        System.out.println("
Total Score: " + total);
    }
}

Limitations of the For-Each Loop (When NOT to Use It)

While elegant, the for-each loop is not a universal replacement for the standard for loop:

• No Index Access: You cannot determine the current index position (e.g. you cannot print "Item at index 3").
• No In-Place Modification: You cannot overwrite array elements (e.g. item = 0; does not modify the underlying array).
• No Reverse Traversal: Traversal is strictly forward from element 0 to length - 1.
• No Structural Deletion: Calling collection.remove() inside a for-each loop throws ConcurrentModificationException.