Why!?

0 - MainActivity.java

public class MainActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity);

        doWork("string_param");
    }

	// Note the parameter variable name (i.e. string)
	private void doWork(final String string) {
	    AsyncTask<Void, Void, String> asyncTask = new AsyncTask<Void, Void, String>() {
	        @Override
	        protected String doInBackground(Void... params) {
	            return "string_async_task";
	        }

	        @Override
	        protected void onPostExecute(String resultString) {
	            // Why is this allowed? If I leave this as is, the log below
	            // prints "string_async_task". If I comment this line out, it 
	            // prints "string_param"
	            String string = resultString;
            
	            Log.e("MainActivity", string);
	        }
	    };

	    asyncTask.executeOnExecutor(AsyncTask.SERIAL_EXECUTOR);
	}
}

1 - MainActivity.class

// class file decoded using JD-GUI (http://jd.benow.ca/)
public class MainActivity extends ActionBarActivity
{
  protected void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(2130968599);
    
    doWork("string_param");
  }
  
  private void doWork(String string)
  {
    AsyncTask<Void, Void, String> asyncTask = new AsyncTask()
    {
      protected String doInBackground(Void... params)
      {
        return "string_async_task";
      }
      
      protected void onPostExecute(String resultString)
      {
        String string = resultString;
        
        Log.e("MainActivity", string);
      }
    };
    asyncTask.executeOnExecutor(AsyncTask.SERIAL_EXECUTOR, new Void[0]);
  }
}

2 - MainActivity$1.class

// class file decoded using JD-GUI (http://jd.benow.ca/)
class MainActivityActivity$1 extends AsyncTask<Void, Void, String>
{
  MainActivityActivity$1(MainActivityActivity paramMainActivityActivity) {}
  
  protected String doInBackground(Void... params)
  {
    return "string_returned_by_async_task";
  }
  
  protected void onPostExecute(String resultString)
  {
    String string = resultString;
    
    Log.e("MainActivity", "paramString = " + string);
  }
}