Java Iterable Interface

Introduction

The Iterable interface in Java represents a collection of objects that can be iterated over. It is used as a foundation for collections to allow for enhanced for-loops and iteration.

Table of Contents

1. What is Iterable?
2. Implementing Iterable
3. Common Methods
4. Examples of Iterable
5. Conclusion

1. What is Iterable?

Iterable is an interface that allows objects to be the target of the "for-each loop." It provides a standard way to iterate over a collection of elements.

2. Implementing Iterable

To implement Iterable, a class must:

• Implement the Iterable<T> interface.
• Override the iterator() method to return an Iterator<T>.

3. Common Methods

• iterator(): Returns an iterator over elements of type T.

4. Examples of Iterable

Example: Implementing Iterable in a Custom Class

This example demonstrates how to implement the Iterable interface in a custom class.

import java.util.Iterator;
import java.util.NoSuchElementException;

public class MyCollection implements Iterable<Integer> {
    private Integer[] items;
    private int size;

    public MyCollection(Integer[] items) {
        this.items = items;
        this.size = items.length;
    }

    @Override
    public Iterator<Integer> iterator() {
        return new Iterator<Integer>() {
            private int index = 0;

            @Override
            public boolean hasNext() {
                return index < size;
            }

            @Override
            public Integer next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
                return items[index++];
            }
        };
    }

    public static void main(String[] args) {
        Integer[] data = {1, 2, 3, 4, 5};
        MyCollection collection = new MyCollection(data);

        for (Integer item : collection) {
            System.out.println(item);
        }
    }
}

Output:

1
2
3
4
5

5. Conclusion

The Iterable interface in Java is a fundamental part of the collections framework, allowing objects to be iterated over easily. By implementing Iterable, you can create custom collections that can be used in enhanced for-loops, improving code readability and functionality.