Boolean vlaue for a video store program - please help!!

[celine scarlett]

Hi,

Any idea how I can add a boolean method that will simply say whether a video is available or not. I have to admit I'm pretty useless with boolean statements and would appreciate any advice.

The program is a simple Video store management program. My current code is as follows,

  
 
package videos;
 
public class Video {
    
    private int days, referenceNumber;
    private static double dailyPrice;
    private double totalPrice;
    private Title videoTitle;
    
    public Video(int refNum, Title t, int d, double dp) {
        referenceNumber = refNum; videoTitle = t; days = d; dailyPrice = dp;
    }
    
    public Video(int title, String film, String lead1, String lead2, String dir){
        videoTitle = new Title(title, film, lead1, lead2, dir);
    }
    
    public Title getTitle() {
        return videoTitle;
    }
    
    public int getReferenceNumber() {
        return referenceNumber;
    }
    
    public void setReferenceNumber(int refNum) {
        referenceNumber = refNum;
    }
    
    public int getDays() {
        return days;
    }
    
    public void setDays(int d) {
        days = d;
    }
    
    public double getDailyPrice() {
        return dailyPrice;
    }
    
    public void setDailyPrice(double dp) {
        dailyPrice = dp;
    }
    
    public double getTotalPrice() {
        return totalPrice;
    }
    
    public void ApplyTotalPrice() {
        totalPrice = days*dailyPrice;
    }
    
    public String toString() {
        return referenceNumber + "" + videoTitle + "" + totalPrice;
    }
}
 

Any help really appreciated!!

[Jeff Albertson]

boolean is treated like any other type in this case, except for a naming convention on the "getter":

public class Video {
    private boolean available;
 
    ...
 
    public boolean isAvailable() {
        return available;
    }
 
    public void setAvailable(boolean available) {
        this.available = available;
    }
}

[celine scarlett]

Hi,

Thanks for the reply. I thought you had to use the conditional statements, if and else, to allow you to specify whether the video is available or not. Something like, 'if' the video is available return true, 'else' return false.

I don't quite see how your solution works.

Any help!!

[Jeff Albertson]

The following are equivalent.

  
public boolean isAvailable() {
        return available;
}
 
public boolean isAvailable() {
    if (available)
        return true;
    else
        return false;
}

Programmers who tend to code in the second manner haven't realized that boolean
is can be treated like any type, because it is a type. If int foo was always 0 or 1,
which method would you write?

  
public int getFoo() {
    return foo;
}
 
public foo getFoo() {
    if (foo==1)
        return 1;
    else 
        return 0;
}

[Ernest Friedman-Hill]

You have to first decide what it means for the video to be available. Jeff's solution assumes that a Video object has a boolean member where you mark each Video object as available or not (we're using "available" to mean the Video exists, but is currently lent out.)

But if, for example, "available" means that the store may or may not own a particular Video, then this implementation might not make sense. Maybe available() needs to be a member of the VideoStore class, and it might look like

private HashMap allVideos;
boolean available(String title) {
  return allVideos.contains(title);
}

where I've assumed your VideoStore class holds all Video objects in a HashMap using the titles as the keys.

So what I'm saying is that first you need to design this facility; then implementing the method is easy.

[celine scarlett]

Hi,

Wow, this is all getting really complicated for me. I know what HashTables are, but I haven't yet learnt how to implement them in Java.

When I say 'available' for a video item, I mean in this case whether the video is available for rental or not. If it is not available this could mean either the store doesn't own it yet, or it is out on loan.

It's a pretty basic program at the moment!

Any help appreciated!

[Ernest Friedman-Hill]

Originally posted by celine scarlett:

When I say 'available' for a video item, I mean in this case whether the video is available for rental or not. If it is not available this could mean either the store doesn't own it yet, or it is out on loan.

OK. So you know that "available" actually is a combination of two different things. One is a property of a Video object (lent or not) while the other is really a property of the VideoStore object (presuming you have one of those.)

So you can ask a single Video object if it's rented or not using what Jeff said; that assumes, then, that when a Video goes out for rental, you're going to call setAvailable(false) and set that boolean member variable to false.

But if you want to know whether the store owns a Video or not, you probably need to ask the VideoStore, right? The VideoStore would need to search through the collection of Videos (I put them in a java.util.HashMap, but you could just use however you're currently doing it). If it doesn't find the Video it wants, then it returns false -- the Video isn't available. Then if the Video does exist, the VideoStore has to call its isAvailable() method so the Video can check its available flag. Make sense?

The coding is the easy part, really -- first you have to decide what you're going to do!

[celine scarlett]

Hi,

Thanks for the reply and the explanation. The details of the videos, borrowers etc are to be stored in a text file/files.

I'll have to give this some real thought, and come back with the code I've implemented based upon your recommendations.

Thank you so much for your help. This might take me a while!!