title: Android: How Intent-Filter works?
body: <p>I read another post: 
  <a href="https://stackoverflow.com/questions/5515257/android-understanding-intent-filters">Android: Understanding Intent-Filters</a> but I still can't grasp what really Intent-filters do and how they work.</p>
  
  <p>For example:</p>
  
  <p>What is the difference between:</p>
  
  <pre><code>        &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
          &lt;/intent-filter&gt;
          &lt;intent-filter&gt;
              &lt;category android:name="android.intent.category.DEFAULT" /&gt;
  
              &lt;action android:name="android.intent.action.SEND" /&gt;
              &lt;action android:name="android.intent.action.SENDTO" /&gt;
  
              &lt;data android:scheme="sms" /&gt;
              &lt;data android:scheme="smsto" /&gt;
              &lt;data android:scheme="mms" /&gt;
              &lt;data android:scheme="mmsto" /&gt;
          &lt;/intent-filter&gt;
  </code></pre>
  
  <p>And</p>
  
  <pre><code>        &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;category android:name="android.intent.category.DEFAULT" /&gt;
  
              &lt;action android:name="android.intent.action.SEND" /&gt;
              &lt;action android:name="android.intent.action.SENDTO" /&gt;
  
              &lt;data android:scheme="sms" /&gt;
              &lt;data android:scheme="smsto" /&gt;
              &lt;data android:scheme="mms" /&gt;
              &lt;data android:scheme="mmsto" /&gt;
          &lt;/intent-filter&gt;
  </code></pre>
  
  <p>Why in the first case the app icon is showed in the app list and in the second case it is not?</p>
  
  <p>When I need to open an Intent-filter and close it?</p>
  
  <p>If I do:</p>
  
  <pre><code>        &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
          &lt;/intent-filter&gt;
          &lt;intent-filter&gt;
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;category android:name="android.intent.category.DEFAULT" /&gt;
           &lt;/intent-filter&gt;
           &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.SEND" /&gt;
              &lt;action android:name="android.intent.action.SENDTO" /&gt;
           &lt;/intent-filter&gt;
           &lt;intent-filter&gt;
              &lt;data android:scheme="sms" /&gt;
              &lt;data android:scheme="smsto" /&gt;
              &lt;data android:scheme="mms" /&gt;
              &lt;data android:scheme="mmsto" /&gt;
          &lt;/intent-filter&gt;
  </code></pre>
  
  <p>Is it correct?</p>
  
  <p>Thanks in advance for the replies and clarifications :)</p>