more help!


DevX Home    Today's Headlines   Articles Archive   Tip Bank   Forums   

Results 1 to 2 of 2

Thread: more help!

  1. #1
    Join Date
    Feb 2005
    Posts
    18

    more help!

    I need help with this one...at the bottom is what I have done so far.

    If P is the population on the first day of the year, B is the birth rate,
    and D is the death rate, the estimated population at the end of the year
    is given by the formula:
    P + B*P - D*P
    100 100

    The population growth rate is given by the formula:
    B-D

    a. growthRate: this method takes as its parameters the birth and death rates,
    and it returns the population growth rate.

    b. estimatedPopulation: this method takes as its parameters the current population,
    population growth rate, and n, the number of years. It returns the
    estimated population after n years.

    Your program should not accept a negative birth rate, negative death rate,
    or a population less than 2.
    ------------------------------------------------------------------------
    import java.io.*;

    public class birthandDeath
    {
    static BufferedReader keyboard =
    new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException
    {
    int startP, birth, death, years;

    System.out.println("Enter the starting population: ");
    System.out.flush();
    startP = Integer.parseInt(keyboard.readLine());
    System.out.println("Enter the birth rate: ");
    System.out.flush();
    birth = Integer.parseInt(keyboard.readLine());
    System.out.println("Enter the death rate: ");
    System.out.flush();
    death = Integer.parseInt(keyboard.readLine());
    System.out.println("Enter the number of years: ");
    System.out.flush();
    years = Integer.parseInt(keyboard.readLine());
    }

  2. #2
    Join Date
    Feb 2005
    Posts
    3
    I think this should be what you need. I tested it and it seemed to work if I understand what you want.

    import java.io.*;

    public class BirthAndDeath
    {
    public static void main(String args[]) throws IOException
    {
    BufferedReader myIn = new BufferedReader(new InputStreamReader(System.in));
    String strStartP, strBirthRate, strDeathRate, strYears;
    int startP, birthRate, deathRate, years, growthRate, estPop;
    boolean done = false;

    while(!done)
    {
    try
    {
    System.out.print("Enter the starting population: ");
    strStartP = myIn.readLine();
    startP = Integer.parseInt(strStartP);
    if(startP < 2)
    throw new NumberFormatException();

    System.out.print("Enter the birth rate: ");
    strBirthRate = myIn.readLine();
    birthRate = Integer.parseInt(strBirthRate);
    if(birthRate < 0)
    throw new NumberFormatException();

    System.out.print("Enter the death rate: ");
    strDeathRate = myIn.readLine();
    deathRate = Integer.parseInt(strDeathRate);
    if(deathRate < 0)
    throw new NumberFormatException();

    System.out.print("Enter the number of years: ");
    strYears = myIn.readLine();
    years = Integer.parseInt(strYears);
    if(years < 0)
    throw new NumberFormatException();

    growthRate = growthRate(birthRate,deathRate);
    estPop = estPop(years, growthRate, startP);

    System.out.println("The estimated population in " + years + " years is " + estPop);
    done = true;
    }
    catch(NumberFormatException e)
    {
    System.out.println("The number entered was not in the correct format.");
    }
    }
    }

    public static int growthRate(int birthRate, int deathRate)
    {
    int growthRate = birthRate - deathRate;
    return growthRate;
    }

    public static int estPop(int years, int growthRate, int startP)
    {
    int estPop = startP + years * growthRate;
    return estPop;
    }
    }
    Last edited by octobclrnts; 02-22-2005 at 07:34 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
HTML5 Development Center
 
 
FAQ
Latest Articles
Java
.NET
XML
Database
Enterprise
Questions? Contact us.
C++
Web Development
Wireless
Latest Tips
Open Source


   Development Centers

   -- Android Development Center
   -- Cloud Development Project Center
   -- HTML5 Development Center
   -- Windows Mobile Development Center