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POBeginning Java Polymorphism Subclass Superclass
 

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    <p>I am trying to practice with Polymorphism and using classes. I wrote a superclass called <code>Card</code>. I then wrote 3 subclasses called: <code>IDCard</code>, <code>CallingCard</code>, and <code>DriverLicense</code>. I then wrote another class called <code>Billfold</code> which is supposed to contain slots for two of the cards.<br> I am supposed to write a <code>BillfoldTester</code> program which adds two objects of different subclasses to a <code>Billfold</code> object. </p> <p>In <code>BillfoldTester</code>, a <code>DriverLicense</code> object and a <code>CallingCard</code> object are instantiated and added to a <code>Billfold</code>, which refers to these objects with <code>Card</code> references. </p> <p>I don't really understand how to do this. I created two <code>Card</code> objects but I am trying to add it to my <code>Billfold</code> and it wont work. I tried <code>Billfold a = new Card (x);</code> but it's not right... Any help is much appreciated.</p> <pre><code>public class BillfoldTester { public static void main (String[]args) { Card x= new IDCard("Julie", 1995); Card j= new DriverLicense("Jess", 1997); //Having trouble trying to put the objects into my Billfold and print it. } } public class Billfold extends Card { private String card1; private String card2; void addCard(String Card)//Not sure if this should be String { card1=Card; } } public class Card { private String name; public Card() //This is my superclass { name = ""; } public Card(String n) { name = n; } public String getName() { return name; } public boolean isExpired() { return false; } public String format() { return "Card holder: " + name; } } public class IDCard extends Card { //This is one of my subclasses private int IDNumber; public IDCard (String n, int id) { super(n); this.IDNumber=id; } public String format() { return super.format() + IDNumber; } } </code></pre>
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    1. USJeff
    1. USLindsay Baird
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    1. COIn theory, when class B extends class A this means that B is some more special kind of A and that B can behave as an A. An `IDCard` is a special `Card` and can do everything a `Card` can. But can you say that about a billfold?
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      1. POBeginning Java Polymorphism Subclass Superclass
      1. USMichael Butscher
 

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