41. The BigDecimal arithmetic example

• The import statement required for BigDecimal arithmetic is

  
  import java.math.*;  // imports all classes and
                       // enumerations in java.math
  
  

• Sample calculation using BigDecimal:

  
  // convert subtotal and discount percent to BigDecimal
  double subtotal = 456.78;
  double discountPercent = 0.2345;
  final double SALES_TAX_PCT = 0.085;
  BigDecimal decimalSubtotal = 
      new BigDecimal(Double.toString(subtotal));
  decimalSubtotal = 
      decimalSubtotal.setScale(2, RoundingMode.HALF_UP);
  BigDecimal decimalDiscountPercent = 
      new BigDecimal(Double.toString(discountPercent));
  // calculate discount amount
  BigDecimal discountAmount = 
      decimalSubtotal.multiply(decimalDiscountPercent);
  discountAmount = discountAmount.setScale(
      2, RoundingMode.HALF_UP);
  // calculate total before tax, sales tax, and total
  BigDecimal totalBeforeTax = 
      decimalSubtotal.subtract(discountAmount);
  BigDecimal salesTaxPercent = 
      new BigDecimal(SALES_TAX_PCT);
  BigDecimal salesTax = 
      salesTaxPercent.multiply(totalBeforeTax);
  salesTax = salesTax.setScale(2, RoundingMode.HALF_UP);
  BigDecimal total = totalBeforeTax.add(salesTax);