Konami Code Helper

KonamiCodeHelper

import android.text.Editable;
import android.text.TextUtils;
import android.text.TextWatcher;
import android.view.Gravity;
import android.widget.EditText;
import android.widget.Toast;

public class KonamiCodeHelper {

    private static final String KONAMI_CODE = "UUDDLRLRBA";

    public interface KonamiCodeCallback {
        public void onKonamiCodeEntered();
    }

    public static void listenKonamiCode(final EditText editText, final KonamiCodeCallback callback) {
        if (editText == null || callback == null) {
            throw new IllegalArgumentException("You must provide an EditText and a KonamiCodeCallback.");
        }

        editText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) { }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (callback != null
                        && isValidKonamiCode(editText.getText().toString())) {
                    final Toast toast = Toast.makeText(editText.getContext(), "Konami Code !!", Toast.LENGTH_SHORT);
                    toast.setGravity(Gravity.CENTER, 0, 0);
                    toast.show();
                    callback.onKonamiCodeEntered();
                }
            }

            @Override
            public void afterTextChanged(Editable s) {}
        });
    }

    private static boolean isValidKonamiCode(String entered) {
        return !TextUtils.isEmpty(entered) && entered.toUpperCase().equalsIgnoreCase(KONAMI_CODE);
    }
}