java dynamic array sizes

## Java Dynamic Array Sizes: A Comprehensive Tutorial with `ArrayList`

In Java, standard arrays have a fixed size determined at the time of declaration. This can be limiting when you don't know the number of elements you'll need to store beforehand. That's where dynamic arrays come in, and in Java, the primary implementation is the `ArrayList` class.

This tutorial will delve into dynamic array capabilities using `ArrayList`, covering its creation, common operations, performance implications, and advanced usage.

**1. What is a Dynamic Array (ArrayList)?**

A dynamic array, unlike a traditional array, can grow or shrink in size during program execution. In Java, `ArrayList` is a resizable array implementation of the `List` interface.

Key characteristics of `ArrayList`:

* **Dynamically Resizable:** It automatically handles resizing as you add or remove elements, so you don't need to worry about exceeding the initial capacity.
* **Ordered Collection:** Elements are stored in the order they are added, and this order is maintained.
* **Allows Duplicates:** `ArrayList` can store duplicate values.
* **Not Thread-Safe:** For concurrent access, you'll need to synchronize access or use a thread-safe alternative like `CopyOnWriteArrayList`.
* **Backed by an Array:** Internally, `ArrayList` uses an array to store its elements. When the array is full, a new, larger array is created, and the elements are copied to the new array.

**2. Creating an `ArrayList`**

Here are several ways to create an `ArrayList`:

* **Empty `ArrayList` with Default Initial Capacity:**



This creates an `ArrayList` that can initially hold 10 elements (this is the default). `ArrayList` uses *generics*, denoted by `String`, which specify the data type that the `ArrayList` will hold. It's best practice to use the `List` interface for declaration as it provides greater flexibility and adheres ...

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