Android Load and run apk file on sdcard

I have found that some app can load a third part app exist in sdcart just decompression the apk file and run... but I can not finger out how to ...

some body know a开发者_如何学Pythonnd give me a help? thanks...

you can install and run the .apk file from your application like below

      Intent intent = new Intent(Intent.ACTION_VIEW);
      intent.setDataAndType(Uri.fromFile(new File(fileName)),  "application/vnd.android.package-archive");
      startActivity(intent);

you can fine more information on this in the following link. http://www.anddev.org/viewtopic.php?p=23928 and automatic install of apk