Chapter 6.1, Problem 4SC

Program Plan Intro

Given Program:

//Definition of class "Investment"

public class Investment

{

    //Declaring private variables

    private double balance;

    private double rate;

    private int year;

    //Declaring an Investment object

    public investment(double aBalance,double aRate)

    {

        balance = aBalance;

        rate = aRate;

        year = 0;

    }

//keeps accumulating interest until a target has been reached

    public void waitForBalance(double targetBalance)

    {

//while loop executes if balance is less than targetBalance

        while(balance < targetBalance)

        {

            //increment year

            year++;

            //Declaring variable interest

            double interest = balance * rate / 100;

            //Defining variable balance

            balance = balance + interest;

        }

    }

    //To get the current investment balance

    public double getBalance()

    {

        return balance;

    //To get the number of years

    public int getYears()

    {

        return year;

    }

}

//Definition of class "InvestmentRunner"

public class InvestmentRunner

{

    //Definition of class main

    public static void main(String[] args)

    {

//initializing the variables INITIAL_BALANCE and RATE

        final double INITIAL_BALANCE = 10000;

        final double RATE = 10;

//declaring the method investment

investment invest = new investment(INITIAL_BALANCE , RATE);

//declaring method waitForBalance

invest.waitForBalance(2 * INITIAL_BALANCE);

//declaring variable years

int years = invest.getYears();

        //Print the statement

System.out.println("The investment doubled after" +years+ “years”);

    }

}

Explanation:

In the above program, the class is named as “Investment”. Inside the class “Investment” three private variables are declared. Then an object of class “Investment” is declared. Then the methods for getting the current investment balance and the number of years are declared. Then inside the “InvestmentRunner” class, there is a main class and inside the main class, the variables “INITIAL_BALANCE”, “RATE” are initialized and then displays the number of years when the investment is doubled.