title: Exception ConcurrentModificationException
body: <p>I wanted to simulate a simple phone application, that can manage contacts and handle messages.
  I have created a function for my manageContacts Function, that I called delteContact.</p>
  <p>However when I try to delete my contact I got this error, I checked my code and I don't see why it would trow that error?</p>
  <pre><code>private static void deleteContact() {
          System.out.println(&quot;Bitte den Namen eingeben:&quot;);
          String name = scanner.next();
          if(name.equals(&quot;&quot;)){
              System.out.println(&quot;Bitte den Namen eingeben:&quot;);
              deleteContact();
          }else{
              boolean doesExist = false;
              for(Contact c : contacts){
                  if(c.getName().equals(name)){
                      doesExist = true;
                      contacts.remove(c);
                  }
              }
              if(!doesExist){
                  System.out.println(&quot;Dieser Kontakt existiert nicht.&quot;);
              }
          }
          showInitialOptions();
      }
  </code></pre>
  <p>Can someone help me where I did here a mistake?</p>