2.9 Methods and parameters

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Methods in Java define the behavior of the class.
Methods are similar to procedures or subroutines in other languages.
The real benefits of object orientation come from hiding the implementation of a class behind its operations.
Methods access the internal implementation details of a class that are hidden from other objects.
Hiding data behind methods is so fundamental to object orientation it has a name - encapsulation.
Methods have zero or more parameters.
A method can have a return value.
A method's statements appear in a block of curly braces { and } that follow the method's signature.
```
    public void speak ()
    {
        System.out.println("Hey Barney ...");
    }
```

Provide an object reference and the method name, separated by a dot (.):
```
    fred.speak();
```
Parameters are passed to methods as a comma-separated list.

A method can return a single value as a result, such as an int:

    public int add (int a, int b)
    {
        return a+b;
    }

A method can return no result:

    public void setFirstName (String firstName)
    {
        this.firstName = firstName;
    }

Occasionally the receiving object needs to know its own reference.

    public void move (double x, double y)
    {
        this.x = x;
        this.y = y;
    }

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