/*
 *  TGn04:  After Autoboxing/Unboxing.  Because of generics, Java knows
 *  what type of objects are in ArrayLists and other collections.  With
 *  that knowledge, on an insertion it can automatically make a Double
 *  object for a double value, saving the programmer the trouble.  This
 *  step is called `autoboxing'.  The resulting code is shorter and
 *  easier to read.
 *
 *  The benefits are also realized when a value is extracted from a
 *  collection; Java can pull the value from a wrapper automatically.
 *  This is called `unboxing'.
 *
 *  Note that when ArrayList is used in the code, its type parameter is
 *  Double, not double.  ArrayList still holds only object references;
 *  asking it to directly reference a base type, such as double, is still
 *  improper.  Java 1.5 (5.0)  just does the wrapping and unwrapping for
 *  you; it doesn't change the collection-of-objects nature of ArrayList.
 *
 *  Also note the formatting of the floating point value in the printf()
 *  call.  This is a convenient way (borrowed from the C language) to
 *  round output to a particular number of decimal places.
 *
 *  It should be no surprise that, if compiled with a Java 1.4 or earlier
 *  compiler, this code will generate errors.
 */

import java.io.*;
import java.util.*;

public class TGn04
{
    public static void main (String [] args) 
    {
        ArrayList<Double> myList;          // We want a collection of Doubles
        double temperature;

        myList = new ArrayList<Double>();  // The new matches the variable

        myList.add(98.6);                  // plain ol' double is `autoboxed'

        temperature = myList.get(0);       // `unbox' the object automatically

        System.out.printf("Someone's temperature is %.2f degrees F.\n",
                          temperature);
    }
}