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Lesson 3 Methods.md

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Methods

  • Writing Methods
  • Calling Methods

Two different things must be done to use methods. First, a method must be written. Second, it must be called.

First, what is a method?

Method -> The 'action' of a class, or what preforms an operation.

Writing Methods

Methods can do two things: preform an operation, and return a type of variable. They can do one, or both. So, let's take our 'dog' example from earlier. You have a dog, who does three things: he sleeps, eats, and barks. All three of these are methods. However, only one of them will return a variable (barks).

public class Dog {
    public String food; 
    public static void run() {
        //this method does not return any kind of variable. 
    }
    public void eat (String food) {
        this.food = food; 
        //this assigns the public variable, assigned just under public class Dog, to the local variable, String food, which is assigned in the method. 
        //It doesn't return anything.
    } 
    public static String bark() {
        return "woof"; 
        //This returns a string.
    }
}

Methods are composed of a few different parts.

First, the modifier, public static. We haven't learned about modifiers yet, but we'll address them shortly.

Second, the return type. This is what kind of variable the method will return-- or, if it doesn't return one, then "void." Void means that nothing will be returned.

Next comes the method name. This is the part of the method that tells us what to call it. For example, bark is a method name.

Third, the body. The body of a method is anything that is contained between the two {curly braces}.

Running Methods

Methods can be run in a few different ways. One can either set a variable equal to a result returned by a method, or simply call the method. Both are listed below:

String dogSays = dog.bark(); //This sets the string equal to "woof", or what the method bark() returns.
dog.eat("biscuit"); //This, however, sets the type of food the dog eats, in the method eat, to biscuit.

Extensions

https://www.w3schools.com/java/java_methods.asp (basics)

https://www.geeksforgeeks.org/methods-in-java/ (in depth)

https://www.tutorialspoint.com/java/java_methods.htm (in depth)