api和isEmpty方法之间的关系是什么

Question

I want to check if the String "registerationId" isImpty :

String registrationId = prefs.getString(PROPERTY_REG_ID, "");
        if (registrationId.isEmpty()) {
            Toast.makeText(this, "registerationid not found in the prefrences",
                    Toast.LENGTH_LONG).show();
            return "";

        }

but the eclipse give me this error call require API level 9 (Current 8). I don't understand what the relation between the API and a String method ? and How suprresLint(New API) effect my project ? thank you very much

Answer 1

Some features require a minimum API level (because that means that basically they were introduced in that API), which must match the one specified in your AndroidManifest.xml file. If you simply ignore it, you risk that when an user with a lower API than the needed installs your app, they'll get unexpected and undesirable effects, like errors, NullPointerException s, etc.

It's always recommended to not ignore these alerts and make your minimal API according to the functions/methods/functionalities that you use.