TwoPartNumber.java:16: error: TwoPartNumber is not abstract and does not overr
ide abstract method initializeUnits() in TwoPartNumber
public class TwoPartNumber
       ^
1 error

TwoPartNumber.java:132: missing method body, or declare abstract
    protected void initializeUnits();

TwoPartNumber.java:67: cannot resolve symbol
symbol  : method initializeUnits ()  

Driver0.java:8: TwoPartNumber is abstract; cannot be instantiated
        number = new TwoPartNumber();

Age 12:
  Mike: 5 feet  5 inches
  Bill: 5 feet  5 inches
    ==   SAME    ==


Age 16:
  Mike: 5 feet  5 inches
  Bill: 5 feet  9 inches
    == DIFFERENT ==


Age 20:
  Mike: 6 feet  6 inches
  Bill: 6 feet  7 inches
    == DIFFERENT ==


Age 70:
  Mike: 6 feet  6 inches
  Bill: 6 feet  6 inches
    ==   SAME    ==

Length.java:10: Length is not abstract and does not override abstract method 
initializeUnits() in TwoPartNumber

public class Length extends TwoPartNumber

/**
 * A weight in traditional U.S. units (i.e., pounds and ounces)
 *
 * This version extends the abstract TwoPartNumber class that
 * implements most behaviors
 */
public class Weight extends TwoPartNumber
{
    /**
     * Default Constructor.
     */
    public Weight()
    {
	super(0, 0);
    }

    /**
     * Explicit Value Constructor.
     *
     * @param pounds  The number of pounds (must be positive)
     * @param ounces  The number of ounces (must be positive)
     */
    public Weight(int pounds, int ounces)
    {
	super(pounds, ounces);
    }

    /**
     * Initialize the "constants" used by a TwoPartNumber.
     */
    protected void initializeUnits()
    {
	smallsPerLarge     = 16;

	largeUnitsSingular = "pound";
	largeUnitsPlural   = "pounds";

	smallUnitsSingular = "ounce";
	smallUnitsPlural   = "ounces";
    }
}

2 feet  1 inch plus 1 pound  9 ounces equals 4 feet  2 inches

    /**
     * Change this Length by a given amount.
     *
     * @param other   The amount to change this Length by
     */
    public void changeBy(Length other)
    {
        super.changeBy(other);
    }

    /**
     * Change this Weight by a given amount.
     *
     * @param other   The amount to change this Weight by
     */
    public void changeBy(Weight other)
    {
        super.changeBy(other);
    }

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

/**
 * A driver.
 */
public class DatabaseDriver2
{
    /**
     * The entry point of the application
     *
     * @param args   The command line arguments
     */
    public static void main(String[] args) throws IOException
    {
       Weight                  weight, result;
       LengthDatabase          database;
       Scanner                 scanner;        
       String                  name, prompt;

       prompt   = "\nName to look for (Ctrl-Z or Ctrl-D to exit): ";       
       database = new LengthDatabase();

       weight = new Weight(155, 8);
       database.add("Mike", weight);

       weight = new Weight(186, 2);
       database.add("Bill", weight);

       weight = new Weight(114, 9);
       database.add("Nancy", weight);

       scanner = new Scanner(System.in);

       System.out.print(prompt);
       while (scanner.hasNext())
       {
          name = scanner.nextLine();
           
          result = database.get(name);
          if (result != null)
          {
             System.out.println(name+" is "+result);
          }
          else
          {
             System.out.println("I don't know how heavy "+name+" is.");
          }

          System.out.print(prompt);
       }
    }
}

DatabaseDriver1.java:44: incompatible types
found   : TwoPartNumber
required: Length
            result = database.get(name);

  result = (Length)database.get(name);

  result = (Weight)database.get(name);

       TwoPartNumber          length, result;

       TwoPartNumber          weight, result;

    /**
     * Calculate the total Length of all objects in this LengthDatabase.
     *
     * @return  The total
     */

    /**
     * Create a default (specialization of) a TwoPartNumber.
     *
     * @return  The TwoPartNumber
     */
    public abstract TwoPartNumber createElement();

public abstract class TwoPartNumberDatabase

/**
 * A simple database that contains weights indexed by a name.
 */
public class WeightDatabase extends TwoPartNumberDatabase
{
    /**
     * Default Constructor.
     */
    public WeightDatabase()
    {
        super();
    }

    /**
     * Add a Weight to the database.  The Weight
     * can be referred to (i.e., indexed by) the given name
     *
     * @param name   The name of the Weight
     * @param value  The Weight
     */
    public void add(String name, Weight value)
    {
        super.add(name, value);
    }

    /**
     * Create a default (specialization of) a TwoPartNumber.
     *
     * @return  The TwoPartNumber
     */
    public TwoPartNumber createElement()
    {
        return new Weight();
    }

    /**
     * Get the Weight with the given name (or null if
     * no such name exists).
     *
     * @param name   The name of the Weight
     * @return       The Weight (or null)
     */
    public Weight get(String name)
    {
        return (Weight)super.get(name);
    }

    /**
     * Get the total TwoPartNumber of all objects in this 
     * TwoPartNumberDatabase.
     *
     * @return  The total
     */
    public Weight total()
    {
        return (Weight)super.totalValue();
    }
}