What makes a method

There are four things that constitute a method:

• a name
• a block of code
• (optionally) accepting input
• returning output

Not all methods actually need input (so they don’t take any), and not always do we care about the output that a method returns.

Imagine a vending machine where you can chip in some money, press some buttons, and the machine will spin a few gears and wheels, and spit out the chocolate bar you were after.

If the vending machine was a method, then your money, as well as the buttons you press are the input. The way the machine internally spins certain mechanics is the block of code, the stuff it does internally. And the product that it dispenses is the return value.

Although this would be an odd thing to mention to a non-programmer, we could say that a vending machine is a way of “transforming” money and data into chocolate.

Methods are a lot like that.

Methods have a name, take some input, do something with it, and return a result.

Programmers usually don’t use the term “input” in this context. Instead we say that a method accepts a number of arguments (pieces of input). And instead of “output” we use the term return value: the thing that we get back from the method.

A method’s input is referred to as “arguments”, while its output is called a “return value”.

This will become more clear in the following chapters. Let’s define a method next.