For Loop vs Enhanced For Loop (for-each) in Java

1. Introduction

In Java, loops are used to repeatedly execute a block of statements. The for loop is a traditional loop that provides explicit control over the initialization, termination, and incrementation of loop variables. The enhanced for loop, also known as the "for-each" loop, was introduced in Java 5 to simplify iteration over arrays and collections without requiring index variables.

2. Key Points

1. The for loop gives you control over the starting point, condition, and increment/decrement in each iteration.

2. The enhanced for loop automatically iterates over all the elements of an array or a collection without using an index variable.

3. In a for loop, you can modify the loop variable and access the loop index.

4. The enhanced for loop is meant for reading each item in a collection or array, not for modifying the loop variable.

3. Differences

for loop	enhanced for loop
Provides explicit control over the loop.	Simplifies the syntax when you only need to read each element.
Allows modification of array or collection elements.	Does not allow modification of array or collection elements directly.
Can be used for any kind of iteration, not limited to collections or arrays.	Can only be used for arrays and collections.

4. Example

public class ForLoopComparison {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};

        // Using traditional for loop
        System.out.println("Using traditional for loop:");
        for (int i = 0; i < numbers.length; i++) {
            // Step 1: Access each element by index
            System.out.println("Number: " + numbers[i]);
        }

        // Using enhanced for loop
        System.out.println("\nUsing enhanced for loop:");
        for (int number : numbers) {
            // Step 2: Access each element directly
            System.out.println("Number: " + number);
        }
    }
}

Output:

Using traditional for loop:
Number: 1
Number: 2
Number: 3
Number: 4
Number: 5
Using enhanced for loop:
Number: 1
Number: 2
Number: 3
Number: 4
Number: 5

Explanation:

1. The traditional for loop iterates over the array using an index to access each element, which allows for modification of the elements if needed.

2. The enhanced for loop iterates directly over each element of the array, simplifying the syntax as there is no need for an index variable.

5. When to use?

- Use the traditional for loop when you need to have explicit control over the iteration, need to modify the elements, or do not iterate over an array or collection.

- Use the enhanced for loop for simplicity and readability when you simply need to access each element of an array or collection without modifying them.