Why do I need to import enum classes to use them when I already imported the package they're in? [Java]

Question

I'm having a little confusion regarding importing packages in Java.

So I have a class with nested enum classes inside:

public class AirCraft extends PublicTransportation 
{
    private AirType classType;
    private TimeType maintainType;
    
    //default constructor
    public AirCraft() {
        super();
        classType = AirType.NONE;
        maintainType = TimeType.NONE;
    }
    
    //nested enums used for AirCraft attributes (2)
    public enum AirType {
        NONE,
        HELICOPTER,
        AIRLINE,
        BALLOON,
        GLIDER
    }
    
    public enum TimeType{
        NONE,
        WEEKLY,
        MONTHLY,
        YEARLY
    }

Then in my driver class I have:

import airTransport.*; //importing the AirCraft class in which resides the two enum classes

public class DriverTransport {

    public static void main(String[] args) {
        //testing AirCraft class methods
        AirCraft secondAir = new AirCraft(50.9, 10, AirType.HELICOPTER, TimeType.MONTHLY);
    }
}

However, I receive a "cannot be resolved to a variable" error for AirType and TimeType. It is fixed if I import them separately, but I'd like to understand why simply importing AirCraft class does not work even though these two enums are inside AirCraft class.

Thanks.

Answer 1

You have used inner enumeration so you have to refer to it via the class it is in:

AirCraft secondAir = new AirCraft(50.9, 10, AirCraft.AirType.HELICOPTER, AirCraft.TimeType.MONTHLY);

you can also statically import the entire enum and use it the way you originally wanted:

import static other.AirCraft.*;

and then:

AirCraft secondAir = new AirCraft(50.9, 10, AirType.HELICOPTER, AirCraft.TimeType.MONTHLY);