You could instead set it to your layout, ie:
LinearLayout mainLayout;
// Get your layout set up, this is just an example
mainLayout = (LinearLayout)findViewById(R.id.myLinearLayout);
// Then just use the following:
InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(mainLayout.getWindowToken(), 0);
This is an example assuming that your layout will be created regardless of how many EditText objects (or other objects) are placed on it.
Edit: Also, something I find very useful is to make sure that the keyboard is hidden when an activity first launches (ie: if an EditText is the first thing focused). To do that, I put this in onCreate() method of Activity:
this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);