This will help you
editText.setInputType(InputType.TYPE_NULL);
Edit:
To show soft keyboard, you have to write following code in long key press event of menu button
editText.setInputType(InputType.TYPE_CLASS_TEXT);
editText.requestFocus();
InputMethodManager mgr = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
mgr.showSoftInput(editText, InputMethodManager.SHOW_FORCED);