Java import packages understanding

Question

i'm learning Java for one year now and this question is confusing me.

At the moment i'm working with Java Swing and i want to know why i have to write the line

import java.awt.event.*;

when i want to use the actionListener even when i've already imported the whole awt package before :/

import java.awt.*

why do i have to tell the compiler to import a Sub-package (is it the right name?), for instance the event package, when i already imported everything under the awt package?

Thanks alot!

Because java.awt and java.awt.event are two different packages. import java.awt.* imports classes from the java.awt package. Not from java.awt.event. Google for "java tutorial import", click on the first link: https://docs.oracle.com/javase/tutorial/java/package/usepkgs.html. And surprisingly enough, it has the answer you're looking for. — JB Nizet, Jul 29 '18 at 09:32

score 0 · Accepted Answer · answered Jul 29 '18 at 09:34

0

Because each package is separate. They don't have a parent-sub relationship.

import java.awt;

doesn't mean that java.awt.event is imported.

answered Jul 29 '18 at 09:34

EmOwen

104
6

It would be great to understand the structure of java libraries! – Murad Alm. Jul 29 '18 at 09:36
@Murad_Alm. It has nothing to do with 'structure'. It has to do with the fact that importing an entire package doesn't import its sub-packages, which in turn is due to the fact that that's the way they designed it. – user207421 Jul 29 '18 at 09:43
Tanks a lot mate! – Murad Alm. Jul 29 '18 at 10:05

Java import packages understanding

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