construction.java

北京大学出版社的

package examples.inheritance;

/** A class used to demonstrate how dynamic binding
  * works when superclass objects are constructed.
  */
public class Construction {
   /** Test method for the class
     * @param args not used
     */
   public static void main( String[] args ) {
      SuperClass y = new SuperClass();
      SubClass x = new SubClass();
      x.g();
   }
}

/** An example superclass */
class SuperClass {
   public SuperClass() {
      f();      // which f() will be called?
   }            // SuperClass.f() or SubClass.f()?

   public void f() {
      System.out.println( "SuperClass.f() called" );
   }

   public void g() {
      f();      // which f() will be called?
   }            // SuperClass.f() or SubClass.f()?
}

/** An example subclass */
class SubClass extends SuperClass {
   public void f() {
      System.out.println( "SubClass.f() called" );
   }
}