No, absolutely not – because if acct is null, it won’t even get to isEmpty… it will immediately throw a NullPointerException.
Your test should be:
if (acct != null && !acct.isEmpty())
Note the use of && here, rather than your || in the previous code; also note how in your previous code, your conditions were wrong anyway – even with && you would only have entered the if body if acct was an empty string.
Alternatively, using Guava:
if (!Strings.isNullOrEmpty(acct))