badcast.java

程序练习中包括书中实例程序代码和练习中要用到的代码,是压缩文件

package examples.rtti;

/** Classes to demonstrate a run-time cast error
  */
public class BadCast {
   /** Test method for the class
     * @param args not used
     */
   public static void main( String[] args ) {
      Mammal horse = new Mammal( "horse" );
      Reptile snake = new Reptile( "snake" );
      Mammal mouse = new Mammal( "mouse" );
      horse.categorize();
      snake.categorize();
      mouse.categorize();
   }
}

/** A generic animal class
  */
class Animal {
   protected String name;

   public Animal( String name ) {
      this.name = name;
   }

   public void categorize() {
      try {
         if ( ((Mammal) this).isRodent() ) {
            System.out.println( "A " + name
                              + " is a rodent." );
         } else {
            System.out.println( "A " + name 
                          + " is not a rodent." );
         }
      }
      catch ( ClassCastException ccx )  {
         ccx.printStackTrace();
      }
      try {
         int legs = ((Reptile) this).numLegs();
         System.out.println( "A " + name + " has "
                             + legs + " legs." );
      } catch ( ClassCastException ccx )  {
         ccx.printStackTrace();
      }
   }
}

/** The class representing all mammals
  */
class Mammal extends Animal {

   private static String[] rodents
      = { "rat", "rabbit", "mouse", "beaver" };

   public Mammal( String name ) {
     super( name );
   }

   public boolean isRodent() {
      for ( int i=0; i < rodents.length; i++ ) {
         if ( name.equals( rodents[i] ) ) {
            return true;
         }
      }
      return false;
   }
}

/** The class representing all reptiles
  */
class Reptile extends Animal {

   public Reptile( String name ) {
      super( name );
   } 

   public int numLegs() {
      if ( name.equals( "snake" ) ) {
         return 0;
      } else {
         return 4;
      }
   }
}