C#/Java communication - C# Discussion Boards

Re: Multiple Datarelations

15-Jan-04 9:45

The first question that comes to mind then is if there is actually related data for the second table's rows. I'm figuring there is, but it has to be asked. Blush | :O

One other thing you could try is to "disconnect" the first relationship and just make sure that the 2->3 table relationship is working correctly.

I seem to remember a similar thread about this problem a long time ago. You could try searching the comments (click "Search Comments") above) to see what was the solution, if any. I suppose it's possible that such a relationship isn't possible, though I would think this is an unlikely possibility.

switchname15-Jan-04 6:24

switchname

15-Jan-04 6:24

Active application?

phimix14-Jan-04 23:32

phimix

14-Jan-04 23:32

Hi
How do I determine if my application is currently active? I.e. I want to see if my app. is the one in focus or if the user has shifted to another app. by clicking it's box in the taskbar, etc.

Thanks for your help,
Mads

Re: Active application?

Mazdak15-Jan-04 2:47

Mazdak

15-Jan-04 2:47

You can overriden Leave event for when it lost focus. Also for regulary check it ,you can check Focused property of form in a timer.

Mazy

No sig. available now.

Re: Active application?

phimix16-Jan-04 3:07

phimix

16-Jan-04 3:07

Thanks for your reply.

Unfortunately, Leave doesn't seem to have the requested effect. The Leave event is not raised when the active application is changed, I think we will try to do a work around using MDI.

C#/Java communication

Norman Fung14-Jan-04 23:31

Norman Fung

14-Jan-04 23:31

I need to get a Java application to communicate with a C# apps. What're the possible ways of doing that? References/Url would be nice. Just want to add that I'm new to Java, and been coding Windows code for the most part of my life. So, please keep in simple and treat me tender.

Thanks in advance.

Norman Fung

Jinwah14-Jan-04 23:50

Jinwah

14-Jan-04 23:50

Depends what you want to communicate but XML would be a good way if you want to do it file/db based. Another would be some sort of Socket based communication not sure how it would go between C# and Java.

Just a little idea

HTH

Luke

Norman Fung15-Jan-04 3:55

Norman Fung

15-Jan-04 3:55

IPC, Java and C#: Is it possible to do this via shared memory...?

Thanks.

Norman Fung

Heath Stewart15-Jan-04 5:04

15-Jan-04 5:04

If you want to actually host .NET controls in a Java application see my article, Embedding .NET Controls in Java[^]. There are also commercial libraries available such as JAWIN and Ja.NET that generate the necessary classes at runtime.

As far as interoperability between Java and .NET at the communications layer, there has been a whole slew of articles on MSDN[^], such as Application Interoperability: Microsoft .NET and J2EE[^].

As for one of your other questions, I suppose you could use IPC but you're going to spend a lot of time just P/Invoking the necessary functions, creating any structs, etc. The articles I mentioned should provide alternatives that can possibly decrease development time and - in some cases - use standard protocols to communicate between the two.

Norman Fung15-Jan-04 6:24

Norman Fung

15-Jan-04 6:24

Hey that's very useful tips. I'll look at it.

Norman Fung

Owner drawn menus

UB14-Jan-04 23:01

14-Jan-04 23:01

How can I create a borderless menu or a transparent menu when creating a owner drawn menu? I have seen this in the Winamp 3x.

UB

You may stop this individual, but you can't stop us all... after all, we're all alike. +++Mentor+++

Re: Owner drawn menus

Heath Stewart15-Jan-04 4:48

Scrolled object positioning

15-Jan-04 4:48

To make a menu transparent, you can use Menu.Handle to get an HWND for the popup window that represents that menu and use the native function SetLayeredWindowAttributes (you'll have to P/Invoke it). To draw the menu without a border, you'll have to handle the MenuItem.DrawItem event and do all the drawing yourself.

You can find several examples here on CodeProject using a search like menu draw[^] or similar. Dr. Gui on MSDN[^] also had a good example some time back at http://msdn.microsoft.com/library/en-us/dnaskdr/html/askgui11062001.asp[^]. The example's in VB.NET but it's mostly method calls (remember, the base class library - or any assembly for that matter - is available to all languages that target the CLR, or ".NET languages", in the same way; though, the syntax for making those calls may be different).

Re: Owner drawn menus

UB16-Jan-04 5:39

16-Jan-04 5:39

Thanks for the advice. I found several articles on CodeProject. To make it borderless they have used subclassing. It's a war out there. Some of them have used hooks, and some of them are against using hooks Smile | :)

By the way I went to geekcode.com, and now I know what's that first three letters mean Smile | :)

Thanks again.

UB

You may stop this individual, but you can't stop us all... after all, we're all alike. +++Mentor+++

Jinwah14-Jan-04 22:08

Jinwah

14-Jan-04 22:08

Can anyone help as I am having a little trouble..

I have a panel with AutoScroll = True. I have added a panel to this control which is bigger than the parent, so scroll bars appear. Then I add another panel calculating the position using

<br />
panelPos = PanelList.Count * APanel.Height;<br />
APanel.Location = new System.Drawing.Point(30, 38 + panelPos);<br />

When the scroll box is not scrolled adding panels puts each one directly below the next as I want. But if the parent is scrolled down then the position is wrong (the new panel is added too low down) by an offset.

I thought the answer would be in the AutoScrollPosition property but I haven't been succesful in making it work.

Any ideas?

TIA

Luke

Re: Scrolled object positioning

Heath Stewart15-Jan-04 4:38

Re: Please give me an idea.

15-Jan-04 4:38

If you look at the documentation for the AutoScrollPosition property, it states that negative values are returned for the X and Y properties of the Point returned from the property if a user has scrolled away from the starting position (0,0). Make sure you negate these values before factoring them into your new position for child panels.

See DirectX 9.0 - Get Ambient with DirectSound[^] which should contain a sample like this (judging by the way the program works).

Please give me an idea.

god4k14-Jan-04 21:31

god4k

14-Jan-04 21:31

Dear, Sir

I will develop an application that automatic check what update on database on the Web Server.
Please give me an idea and overview about it. To get what update via Internet I should use what classs.

I ever create database application, but I never create application that connect to the internet.

And I think I should use thread in this application. Is.... correct?

Thank You.

Sorry for bad English.
Smile | :)

;);P

((

Jinwah14-Jan-04 23:47

Jinwah

14-Jan-04 23:47

You need to read about ADO.NET. Disconnected data sources is the main area.

HTH

Luke

PS: Never appologise for your english (most of us "english" do not speak it very well and the majority cannot even speak another language including me Wink | ;)

Re: Please give me an idea.

Heath Stewart15-Jan-04 4:29

Inserting and Updating BLOBS

15-Jan-04 4:29

As Jinwah was getting at, see the System.Data.DataSet class documentation in the .NET Framework SDK, as well as System.Data.Common.DbDataAdapter - specifically, one of its derived classes depending on what database you're accessing (like System.Data.SqlClient.SqlDataAdapter for a SQL Server database).

You give the DbDataAdapter the appropriate SELECT, INSERT, UPDATE, and DELETE commands (it has properties for each), which you can either use the DataAdapter designer in VS.NET or a CommandBuilder to generate, or type them yourself but generating an example to get an idea might be a good idea.

Then, whenever you update, remove, or insert information in the DataSet, you call DbDataAdapter.Update(DataSet) which will use the change type information for each DataRow and will call the appropriate DbCommand on the DbDataAdapter. There are several examples of this on the CodeProject web site, as well as examples in the .NET Framework SDK.

Guinness4Strength14-Jan-04 18:28

Guinness4Strength

14-Jan-04 18:28

I have the following code:

<br />
<br />
try<br />
{<br />
	string ConnString;<br />
	ConnString="Provider=SQLOLEDB;";<br />
	ConnString+="data source=127.0.0.1;";<br />
	ConnString+="initial catalog=AutoConvert;";<br />
	ConnString+="password=password;";<br />
	ConnString+="persist security info=False;";<br />
	ConnString+="user id=sa;";<br />
	OleDbConnection dbConn = new OleDbConnection(ConnString);<br />
	dbConn.Open();<br />
	<br />
	FileStream fs = File.Open("c:\\temp\\output.dat",FileMode.Open);<br />
	BinaryReader BR = new BinaryReader(fs);<br />
	byte [] BLOB=BR.ReadBytes(Convert.ToInt32(fs.Length));<br />
	DataBase.InsertBLOB(dbConn,"Documents","BatchName","1234567",true,"Document",BLOB);<br />
	dbConn.Close();<br />
<br />
}<br />
catch(Exception Err)<br />
{<br />
	Console.WriteLine(Err.Message);<br />
}<br />
<br />
<br />
<br />
<br />
static public void InsertBLOB(OleDbConnection db,string Table,string LookUpField,string LookUpData,bool IsLookUpString,string BLOBField,byte [] BLOB)<br />
{<br />
	try<br />
	{<br />
		string Command;<br />
		if(IsLookUpString)<br />
			Command= String.Format("UPDATE {0} SET {1}=@{1} WHERE({2}='{3}')",<br />
						Table,BLOBField,LookUpField,LookUpData);<br />
		else<br />
			Command= String.Format("UPDATE {0} SET {1}=@{1} WHERE({2}={3})",<br />
						Table,BLOBField,LookUpField,LookUpData);<br />
		OleDbCommand addEmp = new OleDbCommand(Command, db); <br />
		addEmp.Parameters.Add("@"+BLOBField,BLOB);<br />
		addEmp.ExecuteNonQuery();<br />
	}<br />
	catch(Exception Err)<br />
	{<br />
		throw new Exception(Err.Message);<br />
	}<br />
}<br />

addEmp.ExecuteNonQuery throws an exception witht he message:
"You must define @Document"
I copied the code almost directly from MSDN, but I can't get it to work...Any ideas ?
Oh and in my AutoConvert Catalog I have the table Documents with an image field of length 16 called Document.

Heath Stewart15-Jan-04 4:24

15-Jan-04 4:24

First of all, if you're connecting to a SQL Server, you should be using the class in System.Data.SqlClient. These classes - including the SqlParameter (as opposed to OleDbParameter) are optimized for SQL Server.

Finally, you must define the type of your SqlParameter like so:

SqlParameter parm = addEmp.Parameters.Add("@" + BLOBField, SqlDbType.Image;
parm.Value = BLOB;

See http://msdn.microsoft.com/library/en-us/cpguide/html/cpconwritingblobvaluestodatabase.asp[^] for an example.

Guinness4Strength15-Jan-04 4:44

Guinness4Strength

15-Jan-04 4:44

Thanks for the help as always Heath, I thought SqlConnection and OleDbConnection class were interchangable...

Heath Stewart15-Jan-04 6:54

15-Jan-04 6:54

You can use the System.Data.OleDb classes to access SQL Server, but they are not optimized for any one database - they just use the OLE DB driver using only the common abstract implementations. As far as mixing these two collections of classes together, that's not really supported because most methods in the derived classes take specific types indicitive of their namespace (like a SqlCommand can take a SqlConnection, not a generic DbConnection).