Gain insights into Java programming by exploring conditional statements, loops, math, logic, inheritance, generics, and arraylists, to become an intermediate Java developer.

Learn Java for free with this interactive course, and get a handle on one of the most popular programming languages in the world.

You'll start with a simple hello world program and proceed to cover common concepts such as Conditional Statements, Loop Statements, Math, and Logic in Java, before moving on to more advanced concepts like Inheritance, Generics, and ArrayLists, along with much more.

By the time you're done, you'll be an intermediate level Java developer, ready to take on your own projects.

Learn Intermediate Java

# What is an ArrayList?
>*ArrayList* is a ```class``` in Java which extends the ```AbstractList``` class and implements the ```List``` interface. 



# Why to use ArrayLists?

The length of an Array is set at the time of its declaration and cannot be varied later at any point in the program.
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For example, if the length of an array is set to __5__ at the start of a program it cannot store __more than 5__ elements throughout the program. To overcome this, we will then have to declare a ```new``` array with the length set to some _greater number_ and copy the contents of the previous array to this `new` array. Similarly, if this array is used to store __less than 5__ elements then the excess allocated space is useless and is a wastage of the _memory resource_.

More often, we are not sure of the total number of data items we are going to store in an array later in the program. So, to overcome the said issue we need a *dynamic* variation in the length of an array according to the required space for the storage of elements. This can be easily achieved using the ```ArrayList```.
## How does it work?
An ArrayList actually uses an array to store data. Whenever the number of elements to be stored exceeds the `length` of the current array, the contents of this array are copied and pasted into a ```new``` array of greater size. Hence, the size of an `arrayList` varies dynamically i.e. during the *runtime* of a program.



In this lesson, an explanation of all the basics about the inbuilt ArrayList class in Java is provided.

Getting Started with Java!

Variables & User Input

Simple Maths & Logic

Strings and String Processing

Conditional Statements

Loops

Methods

Arrays

Classes and Inheritance

Generics

ArrayLists

Java Exam

ArrayLists in Java

What is an ArrayList?