Basics of OOP

Object-oriented Programming (usually abbreviated as OOP) is a coding strategy that sets Java apart from many other popular languages, such as Python.

Object-Oriented Programming is dividing up your code into Classes, whose data can be accessed by their Objects. It'll make more sense later.

Why use Object-Oriented Programming?

— OOP is very modular- you can easily change a single segment of your code without having to update dozens of lines of code across different files.

— OOP also lets you control the flow of your code. You can only let specific files access specific fields, keeping your data safe and secure. We won't be going over this much as we will not use it, but make sure to do some research on it.

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OOP Example

Let's say you wanted to make a dungeon crawler with a ton of different characters and enemies in Java. You can make a new class- "Player" or whatever.

Constructors

In Java, we create objects by using the class's constructor. Like a method, the constructor can have parameters. You can think of the parameters as like- custom fields you can set for the player, like health, damage, etc. Here is an example of a constructor.

new Object(parameters) {
    // do something with your variables
}

// constructor of player
new Player(String name, double damage, double health) {
    
    
}

// how you'd access the Player object
Player hero = new Player("Himmel the Hero", 10, 10);

Fields

You know the variables you've been creating in Java? We'll call them fields from now on. By definition, a field is a variable created in a class. Each object can have its own fields, setting them apart from one another. But- how would you access these fields so you can modify them? Here are some strategies.

If you wanted to- let's say, get the health of the hero. You can do this:

// example w/ Player object
hero.Health 

Classes

Your classes are essentially a blueprint. You've been coding in Java classes the entire time. The issue is how you'd access variables through

Objects

woojin— what you're manipulating

Instance Methods

woojin— how you manipulate them