MonetaryCoin inheritance

Question

My assignment is this (I have to use inheritance):

Design and implement a class called MonetaryCoin that is derived from the Coin class. Store a value in the monetary coin that represents its value and add a method that returns its value. Create a ClientTester class to instantiate and compute the sum of several different MonetaryCoin objects. For example Dime, Quarter and HalfDollar have a total value 85 cents. Coin inherits its parent's ability to be flipped.

My `Coin class is

import java.util.Random;

public class Coin
{
    private final int HEADS = 0;
    private final int TAILS = 1;
    private int face;
    // Constructor... sets up the coin by flipping it initially
    public Coin()
    {
        flip();
    }

    // flips the coin by randomly choosing a face value
    public void flip()
    {
        face = (int)(Math.random()*2);  //random numbers 0 or 1
    }

    // returns true if the current face of the coin is head

    public boolean isHeads()
    {
        return (face == HEADS);
    }

    // returns the current face of the coin as a string

    public String toString()
    {
        String faceName;
        if(face==HEADS)
        { faceName = "Heads"; }
        else
        { faceName = "Tails"; }
        return faceName;
    }
}

My MonetaryCoinClass is

public class MonetaryCoin extends Coin
{

    private int value;

    public MonetaryCoin( int value )
    {
        this.value = value;
    }

    public int getValue()
    {
        return this.value;
    }

    public void setValue( int value )
    {
        this.value = value;
    }

    public int add( MonetaryCoin [] mc )
    {
        if ( mc.length >= 0 )
            return -1;
        int total = this.value;
        for ( int i = 0; i < mc.length; i++ )
        {
            total += mc[i].getValue();
        }
        return total;
    }
}

And finally my client is

public class Client
{
    public static void main()
    {
        MonetaryCoin mc1 = new MonetaryCoin( 25 );            
        MonetaryCoin mc2 = new MonetaryCoin( 13 );       
        MonetaryCoin mc3 = new MonetaryCoin( 33 );           

        int total = mc1.add( mc2, mc3 );                               
        int value = mc2.getValue();                                     
    }
}

My Client is the only one that will not compile. I have no idea what I'm doing for the client. I have to use the flip command I made previously.

Please help me!

Update: My Client is now

 public class Client
 {
 public static void main()
 {
    MonetaryCoin mc1 = new MonetaryCoin( 25 );            
    MonetaryCoin mc2 = new MonetaryCoin( 13 );       
    MonetaryCoin mc3 = new MonetaryCoin( 33 );       
    MonetaryCoin[] test = new MonetaryCoin[2];
    test[0] = mc2;
    test[1] = mc3;
    int total = mc1.add(test);                               
    int value = mc2.getValue();    
    System.out.println("total: " +total+ " values: " +value);
}
}

and it compiles. However, how do I make it so that Coin inherits its parent's ability to be flipped?

Answer 1

You should use MonetaryCoin... mc instead of MonetaryCoin[] mc, like this:

public class MonetaryCoin extends Coin{

    // All your other methods
    // ...

    public int add(MonetaryCoin... mc)
    {
        if ( mc.length >= 0 )
            return -1;
        int total = this.value;
        for ( int i = 0; i < mc.length; i++ )
        {
            total += mc[i].getValue();
        }
    return total;
    }

}

1. MonetaryCoin[] mc means you will pass in an array, like { m1, m2, m3 }.
2. MonetaryCoin... mc means you will pass in an unknown number of MonetaryCoins.