//Generalization of example from Page 17, Big Java
//Calculate the number of years needed for a given initial amount
// to compound to a given target amount at a given interest rate
//
import javax.swing.JOptionPane;
public class ExamplePage17B
{
   public static void main(String[] args)
   {
      //Input the starting and target amounts, and interest rate
      String input;  //Input Buffer
      
      input = JOptionPane.showInputDialog(null, "Starting Amount?");
      final double amount = Double.parseDouble(input);
      
      input = JOptionPane.showInputDialog(null, "Target Amount?");
      final double target = Double.parseDouble(input);
      
      input = JOptionPane.showInputDialog(null, "Interest Rate?");
      final double rate = Double.parseDouble(input);

      //Initialize Current Balance, Interest Amount, and Year Count
      double balance = amount;   //Current balance (amount)
      double interest;           //Interest amount each year
      int years = 0;             //#years to achieve the target
      
      //Calculate the # years to achieve the target amount
      while ( balance < target )
      {
         years = years + 1;               //Count another year
         interest = balance * rate/100;   //Calculate the interest
         balance = balance + interest;    //Update current balance
      }
      
      //Display the # years to achieve the target balance
      String info = "It took " + years + " years at " + rate + 
                    "% to increase $" + amount + " to $" + target;
      JOptionPane.showMessageDialog(null, info);
   }
}