Something strange with added in Android Studio .jar lib
<p>I added in my <code>Android Studio Project</code> .jar library.</p>

<p>When I try to use its classes (an example <code>NumberUtils</code> class) inside a package directory, <code>Android Studio</code> is not see classes (but I know, that they exist):</p>

<p><a href="https://i.stack.imgur.com/gLmke.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gLmke.png" alt="enter image description here"></a></p>

<p>But when I create class out of package directory - it's all ok:</p>

<p><a href="https://i.stack.imgur.com/euahI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/euahI.png" alt="enter image description here"></a></p>

<p>How can I use it insida a package?</p>

<p>Edit:
<a href="https://i.stack.imgur.com/Lcoer.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Lcoer.png" alt="enter image description here"></a></p>

<p>Edit 2:
<a href="https://i.stack.imgur.com/xp9n8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xp9n8.png" alt="enter image description here"></a></p>