title: How block the use of java.io.file
body: <p>I'm creating a webpage on my Linux server for my students to compile Java code online: they write their code in a textarea/html and then press a button to compile/execute their programs</p>
  
  <p>The first thinks I want to do, it's prohibit the usage of "java.io.file" ...
  Do you have any tips to block this access?
  I use jdk.8.0_60</p>
  
  <p>I don't know if anyone have some information to up the security of code's execution on my server ...</p>