title: Output directory is not specified in idea project
body: <p>It has a problem in idea:</p>
  
  <blockquote>
    <p>Error:(3, 8) java: 写入edu.nuaa.vo.User时出错: Output directory is not
    specified</p>
  </blockquote>
  
  <p>What does it mean?</p>
  
  <p>My compiler Out path is:</p>
  
  <p><img src="https://i.stack.imgur.com/Gqse1.jpg" alt="enter image description here"></p>