Methods

~ When using a method, are said to invoke or call it.
~ Java has two kinds of methods :
   + Methods that return a single item. Example: method nextInt
   + Methods that perform some action other than returning an item.
      Example: method println
~ Method that perform some action other than returning a value are
   called void methods.
~ A method defined in a class is usually invoked using an object of that class.

Defining void Methods
~ A method definition consists of a heading (1st part of the method
   definition) and a body (the rest of the method definition).

~ Normally, the heading is written on a single line, but if it is too

   long for 1 line, it can be broken into 2 or more lines.
~ The statements in the body are enclosed between braces {}.
~ Instance variables can be use within the body. Such variables are
   called local variables.
*Local variable is confined to the method containing its declaration.

Blocks
~ Is a compound statement that declares a local variable.
~ Same as a compound statement that is a group of
   Java statements enclosed in braces {}.
~ However, the 2 terms tend to be used in different contexts.
~ The variables declared in a block are local to the block and these
   variables disappear when the execution of the block ends.

Parameters of a Primitive Type
~ A formal parameter in a method definition represents the argument.
~ It is given in the heading, within the parentheses right after the
   method name.
~ A formal parameter of a primitive type, such as int, double or
   char is a local variable.
~ Example: public int predictPopulation (int years)
   + The word years is a formal parameter.
   + It is a stand-in value that will plugged in when thr method is called.
   + The item that is plugged in is called an argument or in some
      other books called actual parameters.
~ The way of plugging in arguments (the value of the argument) for
   formal parameters is known as the call-by-value mechanism.
~ This is the only mechanism used for parameters of a primitive
   type in Java.
~ The data type of a formal parameter in a method heading is
   written before the parameter.

Void methods with parameters
modifier (s) void methodName (formal parameter list) 
{                                                                                   
       statements                                                            
}                                                                                   

Methods Calling Methods
~ A method body can contain an invocation of another method.
~ If the called method is in the same class, it is typically invoked
   without writing any receiving object.