CompoundInterest

CompoundInterest.java

/**
 * This program shows how to store tabular data in a 2D array.
 * 
 * @version 1.40 2004-02-10
 * @author Cay Horstmann
 */
public class CompoundInterest {
   public static void main(String[] args) {
      final double STARTRATE = 10;
      final int NRATES = 6;
      final int NYEARS = 10;

      // set interest rates to 10 . . . 15%
      double[] interestRate = new double[NRATES];
      for (int j = 0; j < interestRate.length; j++)
         interestRate[j] = (STARTRATE + j) / 100.0;

      double[][] balances = new double[NYEARS][NRATES];

      // set initial balances to 10000
      for (int j = 0; j < balances[0].length; j++)
         balances[0][j] = 10000;

      // compute interest for future years
      for (int i = 1; i < balances.length; i++) {
         for (int j = 0; j < balances[i].length; j++) {
            // get last year's balances from previous row
            double oldBalance = balances[i - 1][j];

            // compute interest
            double interest = oldBalance * interestRate[j];

            // compute this year's balances
            balances[i][j] = oldBalance + interest;
         }
      }

      // print one row of interest rates
      for (int j = 0; j < interestRate.length; j++)
         System.out.printf("%9.0f%%", 100 * interestRate[j]);

      System.out.println();

      // print balance table
      for (double[] row : balances) {
         // print table row
         for (double b : row)
            System.out.printf("%10.2f", b);

         System.out.println();
      }
   }
}