1. Introduction

Iterating over a List is a fundamental operation in Java, allowing developers to access and manipulate each element in the list. In this guide, we will explore different ways to iterate over a List in Java, including using enhanced for loop, iterator, and Java 8 forEach method.

2. Program Steps

1. Import the necessary libraries.

2. Create and initialize a List.

3. Use different methods to iterate over the list.

4. Output the elements of the list.

3. Code Program

// Step 1: Import the necessary library
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

public class ListIteration {

    public static void main(String[] args) {

        // Step 2: Create and initialize a List
        List<String> fruitList = Arrays.asList("Apple", "Banana", "Cherry", "Date");

        // Step 3: Use different methods to iterate over the list

        // Using enhanced for loop
        System.out.println("Using enhanced for loop:");
        for (String fruit : fruitList) {
            System.out.println(fruit);
        }

        // Using iterator
        System.out.println("Using iterator:");
        Iterator<String> iterator = fruitList.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

        // Using forEach method with lambda expression
        System.out.println("Using forEach with lambda:");
        fruitList.forEach(fruit -> System.out.println(fruit));
    }
}

Output:

Using enhanced for loop:
Apple
Banana
Cherry
Date
Using iterator:
Apple
Banana
Cherry
Date
Using forEach with lambda:
Apple
Banana
Cherry
Date

4. Step By Step Explanation

Step 1: Start by importing the necessary libraries. For this program, we are using List, Arrays, and Iterator.

Step 2: Create and initialize a List with some elements.

Step 3: We use three different methods to iterate over the list.

– Firstly, we use an enhanced for loop, a concise way to traverse each element.

– Secondly, we use an Iterator which provides a way of accessing the elements of an aggregate object sequentially without exposing its underlying representation.

– Lastly, we use the forEach method with a lambda expression, introduced in Java 8, which offers a concise and functional approach for iterating elements.

Step 4: In each iteration method, print out the elements of the list.