Collections and sorting using an interface - C# Discussion Boards

1-Aug-08 21:55

Finally got to a point where I need to use my own interface but got a bit stuck here.

I have a simple interface

public interface IStockItem : IComparable
{
    string StockCode { get; set; }
}

and two structs that implement it fully: SparePart and ServiceTool
and collections of the two structs SparePartCollection<SparePart> and ServiceToolCollection<ServiceTool>

Now I need to get all the SparePart and ServiceTool objects together and sort them by the StockCode property.

What's the best way to collate the object collections to one collection based on the interface, and how do I implement CompareTo on that collection?

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

User 66581-Aug-08 22:56

User 6658

1-Aug-08 22:56

The solution depends on how you sort the SpareParts and ServiceTools.

One solution would be to add both collections to a single collection and then sort using a delegate, like this:

private static int CompareStockItems(IStockItem x, IStockItem y)
{
                // add your sorting algorithm here
    if (x.StockCode.Length < y.StockCode.Length)
        return -1;
    else if (x.StockCode.Length > y.StockCode.Length)
        return 1;
    else
        return 0;
}

List<IStockItem> items = new List<IStockItem>();
items.AddRange(sparePartCollection);
items.AddRange(serviceToolCollection);
items.Sort(CompareStockItems);

You can also just do items.Sort() without specifying a sorting delegate, then the CompareTo methods of the two classes will be used.

This however depends on the implementation of the CompareTo method. If you want SpareParts only to be compared between themselves and ServiceTools also only between ServiceTools, then both CompareTo methods are likely to be different and you'd have to use a delegate to sort them in the list.

If the comparison is the same for both stock item types though, then you can duplicate the CompareTo method in both implementations and use something like:

public int CompareTo(object obj)
{
    IStockItem item = obj as IStockItem;
    if (item == null)
        return -1;
    else
    {
        if (this.StockCode.Length < item.StockCode.Length)
            return -1;
        else if (this.StockCode.Length > item.StockCode.Length)
            return 1;
        else
            return 0;
    }
}

for both stock item implementations. I don't recommend this design though, as a change in one implementation needs to be changed in the other accordingly.

regards

modified 12-Sep-18 21:01pm.

DaveyM692-Aug-08 2:29

2-Aug-08 2:29

Excellent and very helpful answer - thankyou!

I'll have a play with the various solutions ASAP Big Grin | :-D

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

DaveyM692-Aug-08 4:11

2-Aug-08 4:11

Got it working - thanks.

Only problem is using the AddRange method - I get:
Argument '1': cannot convert from 'SparePartCollection' to 'System.Collections.Generic.IEnumerable<IStockItem>'

I can fix this by making the SparePartCollection : List<IStockItem> but that will be no use as I need the collection to be a List<SparePart>

(Obviously the same applies to ServiceToolCollection)

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

DaveyM692-Aug-08 4:48

Re: Collections and sorting using an interface [modified]

2-Aug-08 4:48

I've managed to make it work by using the ConvertAll method but it seems messy!

items.AddRange(spares.ConvertAll(new Converter<SparePart, IStockItem>(SparePart.ToIStockItem)));

and in SparePart struct

public static IStockItem ToIStockItem(SparePart value)
{
    return (IStockItem)value;
}

Is there a better way?

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

User 66582-Aug-08 5:06

User 6658

2-Aug-08 5:06

/edit: my initial advice didn't work.

Looks like you really have to convert the entire collection. However, you can save the static method by using an anonymous method:

items.AddRange(collection.ConvertAll(new Converter<SparePart,IStockItem>(delegate(SparePart value) { return (IStockItem)value; })));

In 3.5 and the System.Linq namespace, you can also use this:

items.AddRange(collection.Cast<IStockItem>());

regards

modified on Saturday, August 2, 2008 11:35 AM

modified 12-Sep-18 21:01pm.

DaveyM692-Aug-08 8:47

2-Aug-08 8:47

Greeeg wrote:
items.AddRange(collection.Cast<istockitem>());

Yay - good old Linq Big Grin | :-D

Thanks for all your help.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

DaveyM692-Aug-08 10:22

How to find the Content datatype in a String

2-Aug-08 10:22

I've adapted your code(s) to my real world code (more complex than the example I posted) and it's working superbly. Thanks very much - again. I wish there was a way I could vote 10 for your help with this!

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

meta file using C#

algates00271-Aug-08 18:56

algates0027

1-Aug-08 18:56

Hi
I am drawing a rectangle using OnmouseClick(vector image)..how can i convert to meta file

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Drawing.Drawing2D;

namespace WindowsApplication2

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

protected override void OnMouseClick(MouseEventArgs e)

{

Graphics g = this.CreateGraphics();

g.DrawRectangle(new Pen(Color.Blue), new Rectangle(e.X, e.Y, 20, 40)); // How can i convert this vector in to a \\ meta file

base.OnMouseClick(e);

}

protected override void OnPaint(PaintEventArgs e)

{

//how to display the meatfile here

base.OnPaint(e);

}

}

}

Can anyone please explain this with source code.

Regards,

ALGATES

algates

Re: meta file using C#

Thomas Stockwell2-Aug-08 7:31

Thomas Stockwell

2-Aug-08 7:31

It is very bad practice to paint on a form through a non-graphic event. (For assistance purposes, I am assuming a meta file is an image). The following is pseudocode (not syntactically accurate).

public Form:Form
{
bool isClickedPerformed=false;
public override OnMouseClick(...)
{
if(e.MouseButton==MouseButton.Right)
    isClickedPerformed=true;
this.invalidate();
}
public override OnPaint(....)
{
if(isClickedPerformed)
e.graphics.drawimage(...follow paramters/usage based on either MSDN Documentation or Object Browser in VS IDE);
}
}

Regards,
Thomas Stockwell

Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.

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K V Sekhar1-Aug-08 18:47

K V Sekhar

1-Aug-08 18:47

Hi all,

How to find Content datatype in a String.

ex: String str="";

In above string accepting only numeric or only characters(string).
i.e: str = "3";
str ="abcdefgh";

I have to find content data type in 'str' variable i.e whether the assigned value is integer or string.

Please suggest me, how to find that.

Thanks in advance
sekhar

Rajesh R Subramanian1-Aug-08 20:59

Rajesh R Subramanian

1-Aug-08 20:59

If you want to accept only a number, why not use an integer? You can always convert the integer to string. I'd be shocked if C# didn't have something like ToString().

Please leave us our small pleasures, they are small, but they are ours! - Mycroft Holmes ^

.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]

DaveyM691-Aug-08 21:11

1-Aug-08 21:11

int.TrypParse(string, out int) method. Some other ther types have the TryParse method too - all return a bool indicating whether it was successful and an out parameter which passes the value to a variable of the type you were checking for.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

Anurag Gandhi1-Aug-08 21:51

Anurag Gandhi

1-Aug-08 21:51

Hi,
you can use regex match to determine its content.

Anurag Gandhi.
http://www.gandhisoft.com
Life is a computer program and every one is the programmer of his own life.

K V Sekhar1-Aug-08 23:06

K V Sekhar

1-Aug-08 23:06

ThanQ for your response.

Could you please write code for that.

Regards
sekhar