Methods

Fundamentals

A method, sometimes called a function, is a block of code that contains a collection of code to execute. You can execute this code by calling the method. In Java, a method consists of a few things:

• Modifiers: an optional list of keywords that give certain qualities to the method
• Return Type: the type returned by the method, or void when not returning anything
• Name: a descriptive method name
• Parameters: an optional list of parameters to be passed into the method
• Scope: the block of code to be executed when the method is called

Modifiers and Return Types

Here's a public method with a void return type.

The modifier is public, meaning any place in the code can call your method. It's not private or protected.

The return type is void. You can think of void as similar to null. It's a keyword that represents the absence of a return type.

public void myMethod()
{
    // Code to execute goes here when myMethod() is called
    // Return type is void, so no need to return anything
}

Here's a public method with a String return type:

public String myMessage()
{
    // Code to execute goes here when myMessage() is called
    // Return type is string, so we must return a string
    return "This is the message";
}

Later in your code, you can call your methods:

myMethod(); // executes any code in your myMethod() method

String message = myMessage(); // executes any code in myMessage() and returns a String

Parameters

Below, we have a method called sendEmail. The return type is boolean, in this case, if the email sent with success. The method has one parameter: String emailAddress.

public boolean sendEmail(String emailAddress)
{
    if (emailAddress.equals("cwinton@truecoders.io"))
    {
        // Send the email and return true, for success
        return true;
    }
    else
    {
        // Don't send the email and return false, for failure
        return false;
    }
}

Later in your code, you can call your methods:

boolean didSendFirst = sendEmail("cwinton@truecoders.io"); // This call will return true

boolean didSendSecond = sendEmail("dwalsh@truecoders.io"); // This call will return false