Error: Could not find or load main class maven project
<p>I have been facing a problem since 2 weeks and I'm getting desperate about solving it as it seems to appear in every new project I make. I have created a new maven project, the java_home variable and the path are set properly with my newly installed java directory, I've cleaned the project with maven clean, there is no apparent error and everything seems fine, but when I run the main class, I get this error telling me Could not find or load main class without any other details. 
It would be really great if you could help me out, thank you in advance.
to provide more info, here is the structure of my project</p>

<p><a href="https://i.stack.imgur.com/cd2Df.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cd2Df.jpg" alt="enter image description here"></a></p>

<p>and here is the code of my main class, I'm using hibernate as well</p>

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

<p>The User_ class is here</p>

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

<p>Finally here are some screen caps in case you need them</p>

<p><a href="https://i.stack.imgur.com/lfkP9.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lfkP9.jpg" alt="enter image description here"></a></p>

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

<p><a href="https://i.stack.imgur.com/IV0is.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IV0is.jpg" alt="enter image description here"></a></p>

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