title: On Android Context.getCacheDir() seems to return a directory I cannot create subdirectories in
body: <p>Does Android not allow creating subdirectories in the cacheDir?  Given that third party (such as advendors) surely will need to cache their own files, it makes lots of sense for me to create a subdirectory for my cached files and let third parties I've integrated manage their own cached files.</p>
  
  <p>Does anyone know how to set the permissions so you can create subdirectories?</p>
  
  <p>Ex. the following code appears to always fail to create a subdirectory.</p>
  
  <pre><code>File cacheDir = context.getCacheDir();
  File subDir = new File(cacheDir, "subdir");
  if ( !subDir.exists() ) {
      if ( !subDir.mkdirs() )
          Log.w(TAG, "Failed to create subdirectory in cache");
  }
  </code></pre>