Introducing delay in a java program

I am calling a .exe file from my java code using :

Runtime r=Runtime.getRuntime开发者_运维技巧();  
Process p=null;
p=r.exec("ABCD.exe");

I want the program to wait till the exe completes its job .(This is actually server side code...control passes to Client side after this).The problem now is that UI on client side is populated before the .exe on server side can form the required components.Hence UI formed does not have the correct files. I have tried the normal p.waitfor() thing but it doesn't seem to work. Any suggestions?

The short answer is that you want to call Process.waitFor() in your main thread, as you allude to.

However, dealing with Processes is not exactly fire-and-forget, because, as referenced by the class javadocs, you likely need to be reading the process' output. If you don't do this (which in this case will require a separate thread) then in many instances you'll have an effective deadlock - your Java app is waiting for the process to finish, but the process is trying to write output to a full buffer and thus waiting for the Java app to read its output.

If you gave more information about how "it didn't work", that would help with the diagnosis too.

Edit: on a completely separate point, there's no purpose in initialising p to null and then immediately reassigning it. Your second line would be clearer and less confusing as Process p = r.exec("ABCD.exe");.