title: Android:How to close dialog after activity destroy?
body: <p>For example, my app have activityA and activityB, activityC, activityA is the mainactivity:</p>
  
  <p>My app has file import feature, so I can import file into my app from sdcard, if you</p>
  
  <p>import file, will open activityC, and you can see the import file in activityC, configure</p>
  
  <p>code:</p>
  
  <pre><code>&lt;activity android:name=".ActivityA"&gt;
  
       &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.VIEW"/&gt; 
              &lt;category android:name="android.intent.category.DEFAULT"/&gt; 
              &lt;data android:mimeType="application/pdf" /&gt; 
              &lt;data ...../&gt;
       &lt;/intent-filter&gt;
  &lt;/activity&gt;
  </code></pre>
  
  <p>Step: Open activityB and pop a dialog ---> Press device home bottom out the app ---> Open file manager app and tap a support file, select myself app in the support list dialog ---->
  app will open, then I can see ActivityC show the import file, but can also see the dialog which pop in activityB.</p>
  
  <p>I want to close the dialog when import file, what can i do?</p>