The following are the steps involved in restricting a program to a single instance :
- Create an instance of the Process class to store the current running process. GetCurrentProcess() will create a new process component and assign it to the current process we are running.
- Create another instance for Process class.Check whether already the same process in running using GetProcessesByName method.
GetProcessesByName method creates an array of process and associates them with all the process component that share the specified process name. Check if the length of the array object is greater than one.If it is then current process is already instantiated. Otherwise allow the process to run.
The code sample below follows the above given algorithm judiciously. In this example, we have implemented the algorithm in the Main() function. This can also be treated as a seperate method if necessary. For example, when a user chooses to run a program, say a music player, which is already running, we might not need another instance of the player. Thus, every time a process is instantiated we need to check if it's already running.
static void Main()
{
Process ThisProcess = Process.GetCurrentProcess();
Process [] AllProcesses = Process.GetProcessesByName(ThisProcess.ProcessName);
if (AllProcesses.Length > 1)
{
MessageBox.Show(ThisProcess.ProcessName + " is already running",
ThisProcess.ProcessName,
MessageBoxButtons.OK,
MessageBoxIcon.Error);
}else {
Application.Run(new MainForm());
}
}
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| Author: Initiotech 31 Jul 2008 | Member Level: Gold Points : 2 |
Good Work Here is an VB.net Version of the Same Code
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Process.GetProcessesByName(Process.GetCurrentProcess.ProcessName).Length() > 1 Then
MsgBox("This is a Single instance Applicaton " & vbNewLine & "* Another Instance is Already Running", MsgBoxStyle.OKOnly, "Single Instance Application")
End
End If
End Sub
Thank You
Regards Hefin Dsouza
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