For-each Loop in Java

Last Updated: 22 March, 2023

For traversing an array or Collection class, Java has introduced another form of the for loop in the Java 5 version that is known as the for-each loop. The for-each loop is a convenient way to iterate over elements in an array or collection, and it can make our code more readable and concise.

The for-each loop is also known as an "enhanced for-loop."

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

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

Writing a for-each loop is very simple in comparison to other Java loops such as the for loop, while loop, or do-while loop. In the for-each loop, we don't have to initialize a loop counter or index variable; we declare a variable that is the same type as the base type of the array, followed by a colon, which is then followed by the array or Collection classes.

Example 1: Traversing an int array using for-each Loop

public class ForEachLoopExample1 { public static void main(String[] args) { // declaring an int array int num_Array[] = { 75, 50, 30, 68, 84 }; System.out.println("Printing Numbers:"); // traversing the int array using for-each loop for (int number : num_Array) { System.out.print(number + " "); } } }

In the above code, the for-each loop iterates over each element in the "num_Array" array, and the value of each element is stored in the "number" variable. The loop then prints out each number to the console.

Output

Printing Numbers:
75 50 30 68 84

Example 2: Traversing a string array using for-each Loop

public class ForEachLoopExample2 { public static void main(String[] args) { // declaring an String array String country_Array[] = { "India", "Japan", "Sri Lanka", "Nepal", "Bangladesh" }; System.out.println("Printing Country Name:"); // traversing the String array using for-each loop for (String country : country_Array) { System.out.println(country); } } }

In the above code, the for-each loop iterates over each element in the "country_Array" array, and the value of each element is stored in the "country" variable. The loop then prints out each number to the console.

Output

Printing Country Name:
India
Japan
Sri Lanka
Nepal
Bangladesh

Example 3: Traversing a char array using for-each Loop

public class ForEachLoopExample3 { public static void main(String[] args) { // declaring an char array and storing vowels char[] vowels = { 'a', 'e', 'i', 'o', 'u' }; // iterating the char array using the for-each loop for (char item : vowels) { System.out.println(item); } } }

In the above code, the for-each loop iterates over each element in the "vowels" array, and the value of each element is stored in the "item" variable. The loop then prints out each number to the console.

Output

a
e
i
o
u

Example 4: Traversing a Collection using for-each Loop

import java.util.ArrayList; public class ForEachLoopExample4 { public static void main(String args[]) { // Creating a list of elements ArrayList<Integer> list = new ArrayList<>(); list.add(1000); list.add(2000); list.add(3000); list.add(4000); list.add(5000); // Store total sum of list int totalSum = 0; // traversing the list of elements using for-each loop for (Integer num : list) { totalSum = totalSum + num; System.out.println(num); } System.out.println("\nTotal Sum of List: " + totalSum); } }

In the above code, the for-each loop iterates over each element in the ArrayList, and the value of each element is stored in the "num" variable. The loop then prints out each number to the console and also adding each element and storing in totalSum variable.

Output

1000
2000
3000
4000
5000
Total Sum of List: 15000

While the Java for-each loop is a powerful feature that simplifies the process of iterating over arrays and collections, it does have some disadvantages that we should be aware of:

• Does not support index-based traversing.
• Not being able to traverse the elements in reverse order.
• Does not allow us to remove elements from a collection while iterating over it. Attempting to do so will result in a runtime exception.
• Performance impact when used with large arrays or collections. This is because it creates an iterator object behind the scenes, which can be less efficient than a traditional for loop.
• Does not guarantee the order in which the elements of a collection will be processed.
• It only works on arrays and collections that implement the Iterable interface. It cannot be used with other types of data structures like maps, sets, or queues.

Despite these disadvantages, the for-each loop is still a powerful feature that can simplify the code and make it easier to read and understand.