title: Android+Facebook: where are API KEY and API SECRET used?
body: <p>I am using FBConnect on Android, it seems that the only ID I need is the app id, which is a string of digits:</p>
  
  <pre><code>Facebook mFacebook = new Facebook(FacebookConstants.APP_ID);
  </code></pre>
  
  <p>But I also got API Key and API Secret when register my app, I wonder where are these used? Did I do something wrong? I looked at the sample code from FBConnect, there is also nowhere using api key and api secret.</p>
  
  <p>Edit:
  Can someone clarify that, are there three keys/IDs: app id, app key and app secret? Below are code from FBConnect's sample project:
      public static final String APP_ID = "175729095772478";</p>
  
  <p>My app's application key does not look like this, mine has non-digits in it.
  And I'm still confused, in Facebook's Doc, there is a command:</p>
  
  <pre><code>keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore 
  | openssl sha1 -binary
  | openssl base64
  </code></pre>
  
  <p>it gives me a string which I can use to register on Facebook, but how does it relate to the application key and secret? I tried FBConnect's sample(the simple one) and I did not do the keytool command, it works; But if I use my app's application key, it does not work.</p>