Few years ago I was looking at legacy code that was developed by offshore team (what could go wrong,right) and I see small utility method that looks like this:

public boolean isEmptyNotEmpty(String s) {
boolean empty=false;
If(s==null) {
empty =true;
}
If(s.equals("")) {
empty = true;
}
return empty;
}

Thinking in myself: was he/she paid per line the line of code??!?!

Up to this date that was the worst part of the code that I encountered....

StringUtils.isNumeric(String s)

From Apache commons-lang library will return TRUE for empty string. I learned that today the hard way...you don't need to make the same mistake... :)

Just update it to lang3 if you are working on legacy code and everyone will be happy...