从空包导入所有内容

Question

I have a package named utilities which has several sub-packages. The utilities package has no classes by itself but the sub-packages do.

I can import all the classes from the sub-packages one by one by doing this:

import utilities.consoleredirect.MessageConsole;
import utilities.generalutils.Helper;
import utilities.generalutils.Pair;
import utilities.generalutils.PropertiesUtils;
import utilities.sqlhandling.Connector;
import utilities.sqlhandling.SQLDatabase;
import utilities.sqlhandling.User;
import utilities.tweetshandling.TwitterTools;
import utilities.tweetshandling.WordCounting;

But if I try to do import utilities.*; I get the error that the package does not exist (in my IDE - NetBeans) but if I try to create the package then I get the error that the file already exists. The folder structure is correct, this is it for easier visualization:

So why can't I just do import utilities.*; and I have to manually import every class?

Answer 1

You can't use a wildcard in an import statement to import other packages , it's just for classes.

So you could do:

import utilities.consoleredirect.*;
import utilities.generalutils.*;
import utilities.sqlhandling.*;
import utilities.tweetshandling.*;

If you're using a sensible IDE, you won't need to think about this very much. Just try and use a class by name and the import statement will be added automagically.