title: Getting ClassNotFoundException in java after removing class file
body: <p>I removed some class file *.class from a java project. It aims to make the whole project folder clean.
  Since the project was compilable and running well, I suppose that it will run faster after I clear some *.class.</p>
  
  <p>However, I got exception java.lang.ClassNotFoundException:</p>
  
  <blockquote>
    <p>at
    java.net.URLClassLoader$1.run(URLClassLoader.java:202)
      at
    java.security.AccessController.doPrivileged(Native
    Method)   at
    java.net.URLClassLoader.findClass(URLClassLoader.java:190)
      at
    java.lang.ClassLoader.loadClass(ClassLoader.java:307)
      at
    sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
      at
    java.lang.ClassLoader.loadClass(ClassLoader.java:248)</p>
  </blockquote>
  
  <p>What is wrong with class loader? </p>