Answer:

A type cast is necessary to tell the compiler that the variable tax in this case contains a reference to a Book object.

public class Store
{
  public static void main ( String[] args )
  {
    Book book ;
    Taxable tax = new Book ( "Emma", 24.95, "Austen" );

    book = (Book)tax;
    System.out.println( book );
    System.out.println( "Tax on item 1 "+ book.calculateTax() );
  }
}

More Practice

Now Consider the following code:

public class Store
{
  public static void main ( String[] args )
  {
    Goods toy ;
    Taxable tax = new Toy ( "Building Blocks", 1.49, 6 );

    toy = tax;
    System.out.println( toy );
    System.out.println( "Tax: "+ toy.calculateTax() );
  }
}

QUESTION 23:

Are type casts necessary? Where should they go? Hint: there are several correct answers.