Lab 22

Question 8 on Page 850.

Hint:

here is the code of class Spices .

import java.util.Scanner;

/**
 Class for data on endangered species.
*/
public class Species
{
    private String name;
    private int population;
    private double growthRate;

    public void readInput( )
    {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("What is the species' name?");
        name = keyboard.nextLine( );

        System.out.println(
                      "What is the population of the species?");
        population = keyboard.nextInt( );
        while (population < 0)
        {
            System.out.println("Population cannot be negative.");
            System.out.println("Reenter population:");
            population = keyboard.nextInt( );
        }

        System.out.println("Enter growth rate (% increase per year):");
       growthRate = keyboard.nextDouble( );
    }

    public void writeOutput( )
    {
         System.out.println("Name = " + name);
         System.out.println("Population = " + population);
         System.out.println("Growth rate = " + growthRate + "%");
    }

    /**
     Precondition: years is a nonnegative number.
     Returns the projected population of the calling object
     after the specified number of years.
    */
    public int predictPopulation(int years)
    {
  int result = 0;
        double populationAmount = population;
        int count = years;
        while ((count > 0) && (populationAmount > 0))
        {
            populationAmount = (populationAmount +
                          (growthRate / 100) * populationAmount);
            count--;
        }
        if (populationAmount > 0)
            result = (int)populationAmount;
 
        return result;
    }

    public void setSpecies(String newName, int newPopulation,
                           double newGrowthRate)
    {
        name = newName;
        if (newPopulation >= 0)
            population = newPopulation;
        else
        {
            System.out.println("ERROR: using a negative population.");
            System.exit(0);
        }
        growthRate = newGrowthRate;
    }

    public String getName( )
    {
        return name;
    }

    public int getPopulation( )
    {
        return population;
    }

    public double getGrowthRate( )
    {
        return growthRate;
    }

    public boolean equals(Species otherObject)
    {
        return (name.equalsIgnoreCase(otherObject.name)) &&
               (population == otherObject.population) &&
               (growthRate == otherObject.growthRate);
    }
}

Here is the code from Listing 12.5 on Page 821.

public class StringLinkedListSelfContained
{
    private ListNode head;

    public StringLinkedListSelf( )
    {
        head = null;
    }

    /**
     Displays the data on the list.
    */
    public void showList( )
    {
        ListNode position = head;
        while (position != null)
        {
            System.out.println(position.data);
            position = position.link;
        }
    }

    /**
     Returns the number of nodes on the list.
    */
    public int length( )
    {
        int count = 0;
        ListNode position = head;
        while (position != null)
        {
            count++;
            position = position.link;
        }
        return count;
    }

    /**
     Adds a node containing the data addData at the 
     start of the list.
    */
    public void addANodeToStart(String addData)
    {
        head = new ListNode(addData, head);
    }

    /**
     Deletes the first node on the list.
    */
    public void deleteHeadNode( )
    {
        if (head != null)
            head = head.link;
        else
        {
            System.out.println("Deleting from an empty list.");
            System.exit(0);
        }
    }

    /**
     Sees whether target is on the list.
    */
    public boolean onList(String target)
    {
        return find(target) != null;
    }

    // Returns a reference to the first node containing the
    // target data. If target is not on the list, returns null.
 private ListNode find(String target)
    {
  boolean found = false;
        ListNode position = head;
        while ((position != null) && !found)
        {
            String dataAtPosition = position.data;
            if (dataAtPosition.equals(target))
    found = true;
   else
    position = position.link;
        }

        return position;
    }

    public String[] toArray( )
    {
        String[] anArray = new String[length( )];

        ListNode position = head;
        int i = 0;
        while (position != null)
        {
            anArray[i] = position.data;
            i++;
            position = position.link;
        }

        return anArray;
    }

    private class ListNode
    {
        private String   data;
        private ListNode link;
  
        public ListNode( )
        {
            link = null;
            data = null;
        }
  
        public ListNode(String newData, ListNode linkValue)
        {
            data = newData;
            link = linkValue;
        }
    }
}