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<p>On the first error, as of JDK 11 (IIRC), the additional root
modules for (the) unnamed module are system modules which have an
unqualified exports (please see JDK-8197532 for more precise and
exact details). So, when compiling code in the unnamed module,
java.se, which does not have any exports, is usually not in the
module graph, and hence is not read by the unnamed module. If
java.se is added to the root modules using `--add-modules java.se`
(for an unnamed module), or via a requires (in case of named
modules), then it should be possible to "import module" from it.</p>
<p><br>
</p>
<p>Jan</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 12. 07. 24 14:27, Tagir Valeev
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAE+3fjbKqgt0C8gYEWQu+yucOa=a21-uYv3cvYJhJ2mfZT=0BA@mail.gmail.com">
<div dir="ltr">Hello!<br>
<div><br>
</div>
<div>I'm playing with module imports and tried to import <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a>
module:</div>
<div><br>
</div>
<div>import module <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a>;<br>
<br>
class Test {<br>
void main() {<br>
ArrayList<String> list;<br>
}<br>
}<br>
</div>
<div><br>
</div>
<div>Building (23-ea+31-2337) yields the following errors:</div>
<div><br>
</div>
<div>>\jdks\jdk-23\bin\java.exe --enable-preview --source=23
Test.java<br>
<a class="moz-txt-link-freetext" href="Test.java:1">Test.java:1</a>: error: unnamed module does not read: <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a><br>
import module <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a>;<br>
^<br>
<a class="moz-txt-link-freetext" href="Test.java:5">Test.java:5</a>: error: cannot find symbol<br>
ArrayList<String> list;<br>
^<br>
symbol: class ArrayList<br>
location: class Test<br>
2 errors<br>
error: compilation failed<br>
</div>
<div><br>
</div>
<div>I'm not sure I understand the first error "unnamed module
does not read". Importing <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a> is
described in JEP 476 text [1], so I assume that it's something
allowed. Is the current behavior intended? If yes, then the
JEP text should probably not mention <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a> as an
allowed example to import.</div>
<div><br>
</div>
<div>The second error is caused by the fact that <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a>
does not declare explicitly that it transitively requires
java.base. It's assumed that any module requires java.base
implicitly, and requires transitive java.base declaration is
not allowed. However, this looks strange with <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a>
specifically: we can import the whole Java SE platform via a
single import declaration _except_ the java.base module.
Contrary, running jshell JAVASE imports the whole Java SE
platform including the java.base module. This looks
inconsistent to me.</div>
<div><br>
</div>
<div>So the question is: is it actually allowed to import <a href="http://java.se" target="_blank" moz-do-not-send="true">java.se</a>,
and should it import java.base automatically?</div>
<div><br>
</div>
<div>With best regards,</div>
<div>Tagir Valeev</div>
<div><br>
</div>
<div>[1] <a href="https://openjdk.org/jeps/476" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://openjdk.org/jeps/476</a></div>
</div>
</blockquote>
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