title: How Eclipse work with and without JDK?
body: <p>I have Eclipse for Java installed on my 64-bit Windows 10. And since than, I was able to do Java development without any configuration.</p>
  
  <p>Previously, the automatically build is selected by default. But when I manually delete the .class files, and want to build again, nothing happens.
  When I try to run the program, it was not surprised that the error message says that it cannot find the class files.</p>
  
  <p>Notice that, from the beginning, I didn't configure JDK in Eclipse, and it worked. 
  I found some source on stack overflow that says, Eclipse has its built-in compiler such that it does not need the javac in JDK. </p>
  
  <p><a href="https://stackoverflow.com/questions/24751032/can-i-develop-java-programs-if-i-have-only-jre-installed/24751065">Can I develop Java programs if I have only JRE installed?</a></p>
  
  <p>But why after I deleted the .class files, the built-in compiler does not work ?</p>