/*

How to run:

Open a command line

Navigate to the folder where this file is

Run "javac Methods.java"

Run "java Methods"

After this, we're going to assume you know how to compile and run

a Java file.

*/

/*

What's a method?

A method is a way to package up a whole bunch of code into one line. It's

a core part of being "DRY", which means "Don't Repeat Yourself." Rule of thumb,

if you have the same code three or more times, it should really be a method.

Methods also improve readability. If you have a method like

"addPlayerToTeam", you can guess what that method does and not

need to worry about how it does it internally.

Let's dive right in.

*/

public class Methods {

public static void main(String[] args) {

int x = 5;

int sum = addWithOutput(x, 4);

/*

This is an example of a method call. Below, we've defined our own

method called "addWithOutput". You can notice methods pretty quickly,

as they'll end with parenthesis. Methods are capable of taking in

pieces of data and using that data to affect what they do. In this case,

the addWithOutput method also outputs some data, which we're storing

in a variable called sum.

*/

System.out.println("sum: " + sum);

// What do you think will be print to the screen?

addWithoutOutput(x, 7);

/*

This will do nothing. See if you can understand why once you read

about this method below.

*/

}

private static int addWithOutput(int a, int b) {

/*

This an example of a method declaration. This first line is called a

method signature.

"private" represents the visibility of the method. Other keywords you can

place here are "protected" and "public." Private means that only the class

this method is defined inside can access it. Protected means any classes

that inherit from this class can use it. We'll cover what that means much

later. Public means that anything anywhere can use this method.

"int" is where you define the type of data this method spits out. In this

case, we're going to produce an integer as output.

addWithOutput is the method name.

(int a, int b) is our parameter listing. This defines the data that the

method can take as inputs. It requires the data type and a name for the

data that you can use within the method. In this case, whatever value is

provided as the first parameter will be called "a," and the second

parameter's data will be referred to as "b." This is independent of whatever

the data was called before it was given to the method.

Ignore static for now :^)

*/

return a + b;

/*

Return is a keyword that ends the method and passes whatever value

after it as output. In this case, we're outputting the sum of a and b.

*/

}

private static void addWithoutOutput(int a, int b) {

/*

void is not a data type. Void means that this method produces no output.

This specific method effectively does nothing. This would be useful if

we need to internally modify some data but don't need to provide any output.

*/

int useless = a + b;

return;

// See? not returning anything. Technically, this line isn't even required.

}

}

/*

In summary, methods are defined somewhere. They are then called elsewhere.

They can even call themselves, but more on that later. Again, methods help

keep your code simple. They're absolutely vital to almost all code you'll

write in the future.

*/