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This page contains an archived post to the Java Answers Forum made prior to February 25, 2002.
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Message:
Help me!
Posted by Kevin on November 29, 2001 at 3:28 PM
I~{!/~}m a tyro in java. I made a test for inheritance and polymorphism. But there is a problem that I can~{!/~}t understand. Who can help me?
The source code is as follows:
The base class is in directory – PKG. package pkg; public class Cat
{
protected Cat()
{
System.out.println("Cat construction()");
}
protected void what()
{
System.out.println("This is Cat");
}
protected void finalize() throws Throwable
{
System.out.println("Cat finalize()");
super.finalize();
}
} The derived classes are in the upward directory of PKG :
import pkg.*; class BlackCat extends Cat
{
BlackCat()
{
System.out.println("BlackCat construction()");
}
protected void what()
{
System.out.println("This is BlackCat");
}
protected void finalize() throws Throwable
{
System.out.println("BlackCat finalize()");
super.finalize();
}
}
public class BabyBlackCat extends BlackCat
{
BabyBlackCat()
{
System.out.println("BabyBlackCat construction()");
}
protected void finalize() throws Throwable
{
System.out.println("BabyBlackCat finalize()");
super.finalize();
}
protected void what()
{
System.out.println("This is BabyBlackCat");
}
public static void main(String args[])
{
BabyBlackCat babycat = new BabyBlackCat();
//! Cat a = new Cat();
//! Cat b = new BlackCat();
//! Cat c = new BabyBlackCat();
//! a.what();
//! b.what();
//! c.what();
}
} The problem sentences are flagged by ~{!0~}//!~{!1~}. If you uncomment it, you will get error message – ~{!0~}what() has protected access in pkg.Cat~{!1~}. Thank you very much.
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