Access Cookbook

Check to See if an Application Is Already Running

Problem

You need to start up other Windows programs from within your Access application—for instance, to send data to Excel or to format a report in Word. If you just use the Shell command to start these programs, you may end up with multiple instances of the application. How can you tell if an application is already running before you attempt to start it?

Solution

There are a number of solutions to this problem, and none, unfortunately, are as easy as you might like. To ask Windows whether Excel is currently running and receive an answer, you must know the Windows class name for the main window of the application. This solution explains the format of the question and how to ask it. In addition, it demonstrates how to switch to a running application from your Access application.

If you have code that interacts with applications external to Access, it is often useful to be able to determine whether the application is running. The sample form, frmAppsRunning (Figure 11-10), asks Windows the question, “Is this app running?” for each of six predefined window classes, and you can add one more of your own. For each application that frmAppsRunning finds, it fills in the window handle (hWnd) column and the window caption column on the form. The AppActivate command in Access requires that you know the exact title of the window, so this form uses code from Chapter 4 (in basAccessCaption) to retrieve the caption for each running application. ...