How to judge the commond called by Runtime executed successfully or not

I use java.lang.Runtime to call some standalone executeable commond (which will open another application do some operation use a comond line manner) in my application,however I can not judge whether the commond is executed or whether it is executed successfully. And someone tell me I should define the standard for judge the success and failture. But I have no idea.

In my opinion,take the "dir" for example(although it is a interpret commond), if the output is the contents of a directory, it is success,if it give other messages,it is false,so in this case ,how to express my meaning in the java codes?

I would like some can give me some advice or example.Thanks.