Curriculum
Course: Learn Java Programming
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Curriculum

Learn Java Programming

Chapter 0: Computer Language Generations and Environment Setup

0/4

Chapter 1: Introduction to Java

0/6

Chapter 2: Java Data Types, Tokens and Variables

0/5

Chapter 3: Working with User Input in Java

0/6

Chapter 4: Java Operators and Expressions

0/9

Chapter 5: Understanding Control Statements in Java

0/8

Chapter 6: Working with Wrapper Classes Arrays in Java

0/6

Chapter 7: Understanding Classes and Methods in Java Part 1

0/9

Chapter 8: Understanding Constructors and Encapsulation in Java

0/8

Chapter 8: Understanding Methods and Objects in Java Part 2

0/5

Chapter 9: Working with Inheritance and Polymorphism in Java

0/11

Chapter 10: Working with Package, Abstract Class and Interface in Java

0/9

Chapter 11: String Handling in Java

0/5

Chapter 12: Understanding Error and Exception Handling in Java

0/13

Chapter 13: Working with I/O Stream Classes and File Handling in Java

0/10

Chapter 14: Working with Multithreading in Java

0/11

Chapter 15: Working with Generics

0/4

Chapter 16: Working with Collection Frameworks

0/8

Chapter 17: Working with AWT and Swings in Java

0/17

Chapter 18: Event Handling in Java

0/4

Chapter 19: Working with JDBC in Java - Part 1

0/11

Chapter 20: Working with JDBC in Java - Part 2

0/2
Video lesson

Understanding for-each loop in Java

In this lesson, you will learn

  • For-Each Loop in Java
  • Examples

 

What is the For-Each Loop in Java?

  • The for-each loop is a simplified way to iterate over elements in arrays and collections (like lists) in Java.
  • It eliminates the need for explicit index management, making your code cleaner and less error-prone.
  • It’s particularly useful when you want to process each element in a sequence without needing to know its position.

Syntax:

for (elementType elementVariable : arrayOrCollection) {
    // Code to be executed for each element
    // elementVariable holds the current element's value
}
  • elementType: The data type of the elements in the array or collection.
  • elementVariable: A variable that will hold the value of each element during each iteration.
  • arrayOrCollection: The array or collection you want to iterate over.

 

How to Use For-Each Loop for 1D Arrays:

public class ForEach1DArray {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};

        System.out.println("Elements of the array:");
        for (int number : numbers) {
            System.out.println(number);
        }

        // Example of summing the elements
        int sum = 0;
        for (int number : numbers) {
            sum += number;
        }
        System.out.println("Sum of the elements: " + sum);
    }
}

Output

Elements of the array:
1
2
3
4
5
Sum of the elements: 15

 

How to Use For-Each Loop for 2D Arrays:

When using a for-each loop with a 2D array, you’ll need nested loops. The outer loop iterates over the rows, and the inner loop iterates over the elements in each row.

public class ForEach2DArray {
    public static void main(String[] args) {
        int[][] matrix = {
                {1, 2, 3},
                {4, 5, 6},
                {7, 8, 9}
        };

        System.out.println("Elements of the 2D array:");
        for (int[] row : matrix) { // Outer loop: iterates through rows
            for (int element : row) { // Inner loop: iterates through elements in each row
                System.out.print(element + " ");
            }
            System.out.println(); // Move to the next line after each row
        }

        //Example of summing all elements in the 2D array.
        int totalSum = 0;
        for (int[] row : matrix){
            for(int element : row){
                totalSum+=element;
            }
        }
        System.out.println("The total sum of all elements is: " + totalSum);
    }
}

Output

Elements of the 2D array:
1 2 3 
4 5 6 
7 8 9 
The total sum of all elements is: 45

 

Key Advantages of For-Each Loop:

  • Readability: It makes code cleaner and easier to understand.
  • Reduced Errors: It eliminates the risk of off-by-one errors that can occur when using traditional for loops with indices.
  • Simplicity: It simplifies iteration over arrays and collections.

Limitations:

  • You cannot modify the elements of the array or collection directly within the loop.
  • You cannot access the index of the current element.
  • You cannot iterate in reverse.

 

Therefore, to take user input and store it in an array, you’ll need to use a traditional for loop with an index. Here’s a breakdown and example:

Why For-Each Doesn’t Work for Input:

  • Read-Only Access:
    • The for-each loop provides a copy of each element’s value to the loop variable.
    • Modifying that loop variable does not change the original array element.

How to Take User Input and Store in an Array:

Here’s the correct way to do it using a standard for loop:

import java.util.Scanner;

public class ArrayUserInput {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the size of the array: ");
        int size = scanner.nextInt();

        int[] numbers = new int[size];

        System.out.println("Enter " + size + " numbers:");

        // Use a traditional for loop to take input
        for (int i = 0; i < numbers.length; i++) {
            numbers[i] = scanner.nextInt();
        }

        System.out.println("Array elements:");

        // Now, you can use a for-each loop to display the array
        for (int number : numbers) {
            System.out.print(number + " ");
        }
        System.out.println();

        scanner.close();
    }
}

Output

Enter the size of the array: 5
Enter 5 numbers:
4
5
6
7
8
Array elements:
4 5 6 7 8

 

 

End of the lesson….enjoy learning

 

 

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30/10/2025

There is some overlapping of the content making it bit unreadable. Please verify.

 

 

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