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Enhanced for-each Loop

The enhanced for-each loop (also called the for-each loop) is a simplified looping construct introduced in Java 5. It is used to iterate over arrays and collections without managing indexes explicitly. This loop improves readability, safety, and maintainability, especially when index access is not required.

What Is the Enhanced for-each Loop?

Used to iterate over arrays and collections
Eliminates index handling
Executes sequentially from first to last element
Read-only access to elements

Basic Syntax

for (dataType variable : collectionOrArray) {
    // code to execute
}

Simple Example with Array

int[] numbers = {10, 20, 30, 40};
for (int num : numbers) {
    System.out.println(num);
}

Output:

Example with String Array

String[] languages = {"Java", "Python", "C"};
for (String lang : languages) {
    System.out.println(lang);
}

Example with Collections

List names = new ArrayList<>();
names.add("Alice");
names.add("Bob");
for (String name : names) {
    System.out.println(name);
}

Execution Flow

Loop variable gets one element per iteration
Loop continues until all elements are processed
No index variable involved

When to Use Enhanced for-each Loop

Traversing arrays
Reading elements from collections
When index value is not required
When no modification of structure is needed

When NOT to Use Enhanced for-each Loop

When you need:
Index access
Reverse iteration
Element removal during iteration
Conditional skipping based on index

// ❌ Cannot remove elements safely
for (String s : list) {
    list.remove(s);
}

Enhanced for-each vs Traditional for Loop

Feature	Enhanced for-each	Traditional for
Index Access	❌ No	✅ Yes
Readability	High	Medium
Modification	❌ No	✅ Yes
Reverse Loop	❌ No	✅ Yes
Best For	Traversal	Control-based logic

Enhanced for-each with 2D Arrays

int[][] matrix = {
    {1, 2},
    {3, 4}
};
for (int[] row : matrix) {
    for (int value : row) {
        System.out.print(value + " ");
    }
    System.out.println();
}

Common Beginner Mistakes

Expecting index value
Trying to modify array/collection structure
Confusing with iterator-based loops
Using for-each when index is required

Interview-Ready Answers

Short Answer

The enhanced for-each loop is used to iterate over arrays and collections without using indexes.

Detailed Answer

The enhanced for-each loop simplifies iteration by automatically accessing each element in a collection or array. It improves readability but does not allow index-based access or structural modification.

Key Takeaway

The enhanced for-each loop is ideal for simple traversal. Use it when you want clean, readable code and do not need index control.