[Android] Monitor Package Event: install/uninstall

1. Define a class derived from class BroadcastReceiver;
2. Register broadcast receiver;
   MyBroadcastReceiver myReceiver = new MyBroadcastReceiver();
   IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_INSTALL);
   filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
   filter.addAction(Intent.ACTION_PACKAGE_ADDED);
   filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
   filter.addAction(Intent.ACTION_PACKAGE_RESTARTED);
   ...
   filter.addDataScheme("package"); //This line is very important. Otherwise,
   broadcast can't be received.
   registerReceiver(myReceiver, filter);
   
   Notes: The package name is Intent.mData. Intent.mData is not available in SDK 1.0, but it can be retrieved by calling Intent.getDataString();
3. Uninstall package
1. Uninstall application in code
   Uri uri = Uri.formParts("package", , null);
   Intent intent = new Intent(Intent.ACTION_DELETE, uri);
   context.startActivity(intent);
   
2. Check if application is uninstalled successfully
1. Uninstall succeeded
   - Define a broadcast receiver to monitor Intent.ACTION_PACKAGE_REMOVED
   - Register such broadcast receiver
2. Uninstall failed/succeeded
   - Launch package uninstalled with:
   activity.startActivityForResult(intent, );
   
   - Get result
   protected void onActivityResult(int requestCode, int resultCode, Intent data)
   {
       if (requestCode == )  //resultCode always is 0, and the intent argument 'data' is always null
       {
          //call packagemanager.getPackageInfo, return null if package is uninstalled
       }
   }
   
   Note: This method is not invoked if the package is uninstalled successfully
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