# ArrayList Manipulation: add, remove Elements, find size

Problem Statement: Write a Java program to create an ArrayList of integers, add elements, remove elements, and find the size of the list.

Here’s a Java program that demonstrates how to create an `ArrayList` of integers, add elements to it, remove elements from it, and find the size of the list. I’ll provide a thorough explanation of the logic behind each step.

```package com.javacodepoint.collection;

import java.util.ArrayList;

public class ArrayListManipulation {

public static void main(String[] args) {
// Create an ArrayList to store integers
ArrayList<Integer> numbers = new ArrayList<>();

// Adding elements to the ArrayList

System.out.println("ArrayList after adding elements: " + numbers);

// Removing an element from the ArrayList
numbers.remove(1); // Remove the element at index 1 (20)

System.out.println("ArrayList after removing element at index 1: " + numbers);

// Finding the size of the ArrayList
int size = numbers.size(); // Get the number of elements in the list

System.out.println("Size of the ArrayList: " + size);
}
}

```

OUTPUT:

ArrayList after adding elements: [10, 20, 30]
ArrayList after removing element at index 1: [10, 30]
Size of the ArrayList: 2

Explanation:

1. Import Statement: The `import` statement is used to import the necessary classes. In this case, we’re importing the `ArrayList` class from the `java.util` package.
2. Creating an ArrayList: We create an `ArrayList` named `numbers` that will store integers. We specify the type of elements the list will hold using the angle brackets (`<>`) and the type parameter (`Integer` in this case).
3. Adding Elements: We use the `add()` method to add integers to the `numbers` list. We add three integers: 10, 20, and 30. The `add()` method appends elements to the end of the list.
4. Printing the ArrayList: We use the `System.out.println()` statement to print the contents of the `numbers` list after adding the elements.
5. Removing an Element: We use the `remove()` method to remove an element from the list. In this case, we remove the element at index 1, which is the integer 20.
6. Printing the Modified ArrayList: We print the contents of the `numbers` list again after removing the element at index 1.
7. Finding the Size: We use the `size()` method to find the number of elements in the `numbers` list. The result is stored in the `size` variable.
8. Printing the Size: We print the size of the `numbers` list using the `System.out.println()` statement.

By following these steps, the program demonstrates how to create an `ArrayList` of integers, add elements to it, remove elements from it, and find the size of the list. This is a fundamental example of working with collections in Java.