title: How to run Java my project with eclipse
body: <p>I have started learning Java and I have 1 issue:</p>
  
  <p>I write a simple class and it runs and everything's fine.
  I took all the project from my Laptop to my other computer and from Eclipse I choose "File --> Open File" and choose my .java file.</p>
  
  <p>When I try to run my program this windows pop up:</p>
  
  <p><img src="https://i.stack.imgur.com/8CM4V.jpg" alt="enter image description here"></p>
  
  <p>and after trying both option nothing happen.</p>
  
  <p>How can I run my program and what is the problem ?</p>