Java Beginners: What Is an Object Actually?

[u/jadu2115]

I'm a Java learner and I've been learning Java for the past few months, but I still don't truly understand what an object actually is.

I've watched several YouTube videos and used AI tools to understand it, but I keep getting the same explanation: "An object is nothing but data + code."

I understand the definition, but I still can't visualize or feel what an object actually is when I'm writing Java code.

Could someone explain it in a simple, practical way, preferably with a real world analogy and a small Java example?

I feel like I'm missing one fundamental concept here. Any explanation would be really helpful. Thanks!

[u/PhilNEvo]

One way I think might help the intuition of it, is to think of it like a data-type.

Let's start with a simple datatype I bet you already know, something like an "int". You can think of "int" as having some pre-defined characteristics. It defines a 32-bit number, that you can use in some ways. For example, you can do arithmetic with it against other ints.

You can think of all those specifications, that tells you the size of it, what it contains, what it can do, as a "class", where the attribute of the class defines data it holds, in this situation it would be a 32-bit value. Methods of that class defines how ints must behave and interact with other datatypes.

Now when you declare a variable somewhere:
int i = 5;

you're saying "Hey, the datatype that int 'class' specifies, I want to 'spawn' that as an object, where the 32-bit value it holds should be 5".

Now just like there exists datatypes that can hold multiple values, such as an Array. The limitation of a regular Array is that all of the values must be of a similar type. So in cases where you want to spawn a datatype, that holds multiple different values, that has quite unique behavior for your specific application, you would want to create a datatype that fits your needs.

This could be a "Player" character in a game, where you want to store its x,y coordinate, its health and you want to define moves it can make such as jump, run, shoot. You create the template for said player datatype with a class, and then whenever you want to "spawn" a player in your game, you use that datatype and instantiate one as an object.

Usually instantiating one as an object just means to reserve a space in memory for that datatype, and hold a reference, such as a label "Player1", to it, so you can use it and interact with it. Just like you would with the "i" we previously made of int, that was equal to 5.