Java for-each Loop

Introduction

The enhanced for loop, also known as the for-each loop, is used to iterate over arrays and collections. It provides a more readable and concise way to traverse through elements, eliminating the need for an explicit counter or index variable. In this chapter, we will explore the syntax, usage, and examples of the for-each loop in Java.

Syntax

The basic syntax of the for-each loop is as follows:

for (type variable : array) {
    // code to be executed
}

Key Points:

• type: The data type of the elements in the array.
• variable: A temporary variable that holds each element of the array during iteration.
• array: The array to be iterated over.

Example: Iterating Over an Array

Let’s consider an example where we use the for-each loop to print elements of an array.

Example Code:

public class ForEachExample {
    public static void main(String[] args) {
        // Array of integers
        int[] numbers = {1, 2, 3, 4, 5};

        // Enhanced for loop to iterate over the array
        for (int num : numbers) {
            // Print the current element of the array
            System.out.println("Number: " + num);
        }
    }
}

Output:

Number: 1
Number: 2
Number: 3
Number: 4
Number: 5

Example: Iterating Over a String Array

Let’s consider another example where we use the for-each loop to print elements of a string array.

Example Code:

public class ForEachStringExample {
    public static void main(String[] args) {
        // Array of strings
        String[] fruits = {"Apple", "Banana", "Cherry", "Date"};

        // Enhanced for loop to iterate over the array
        for (String fruit : fruits) {
            // Print the current element of the array
            System.out.println("Fruit: " + fruit);
        }
    }
}

Output:

Fruit: Apple
Fruit: Banana
Fruit: Cherry
Fruit: Date

Example: Summing Elements in an Array

Let’s consider an example where we use the for-each loop to calculate the sum of elements in an array.

Example Code:

public class SumForEachExample {
    public static void main(String[] args) {
        // Array of integers
        int[] numbers = {1, 2, 3, 4, 5};
        int sum = 0;

        // Enhanced for loop to iterate over the array
        for (int num : numbers) {
            // Add the current element to the sum
            sum += num;
        }

        // Print the calculated sum
        System.out.println("Sum: " + sum);
    }
}

Output:

Sum: 15

Example: Finding the Maximum Element in an Array

Let’s consider an example where we use the for-each loop to find the maximum element in an array.

Example Code:

public class MaxForEachExample {
    public static void main(String[] args) {
        // Array of integers
        int[] numbers = {1, 2, 3, 4, 5};
        int max = numbers[0];

        // Enhanced for loop to iterate over the array
        for (int num : numbers) {
            // Update max if the current element is greater
            if (num > max) {
                max = num;
            }
        }

        // Print the maximum element
        System.out.println("Maximum: " + max);
    }
}

Output:

Maximum: 5

Diagram: Flow Chart of for-each Loop

   Start
     |
 [initialize]
     |
 [for-each element in array]
     |
 [execute loop body]
     |
 [next element]
     |
 [all elements processed]
     |
    End

Conclusion

The for-each loop is a useful and concise control flow statement in Java that simplifies the process of iterating over arrays. It enhances code readability and reduces the likelihood of errors associated with traditional for loops. By understanding the syntax and various use cases of the for-each loop, you can write more efficient and cleaner Java code.