put up NFC button even if turned off, and when it's used offer to turn

it on.

xwords4/android/XWords4/res/values/strings.xml

@@ -2176,4 +2176,8 @@
     <string name="dropped_dupe">Invitation ignored: already used</string>
     <string name="cur_menu_markerf">%1$s (yours)</string>
     <string name="board_menu_invite">Invite</string>
+
+    <string name="enable_nfc">NFC is turned off on this device. Use
+    the Android Settings app to turn it on .</string>
+    <string name="button_go_settings">Launch Settings</string>
 </resources>

xwords4/android/XWords4/src/org/eehouse/android/xw4/BoardActivity.java

@@ -86,6 +86,7 @@ public class BoardActivity extends XWActivity
     private static final int DLG_GETDICT = DLG_OKONLY + 13;
     private static final int GAME_OVER = DLG_OKONLY + 14;
     private static final int DLG_CONNSTAT = DLG_OKONLY + 15;
+    private static final int ENABLE_NFC = DLG_OKONLY + 16;
 
     private static final int CHAT_REQUEST = 1;
     private static final int BT_INVITE_RESULT = 2;
@@ -512,6 +513,22 @@ public class BoardActivity extends XWActivity
                 }
                 break;
 
+            case ENABLE_NFC:
+                lstnr = new DialogInterface.OnClickListener() {
+                        public void onClick( DialogInterface dialog, 
+                                             int item ) {
+                            startActivity( new Intent("android.settings"
+                                                      + ".NFC_SETTINGS" ) );
+                        }
+                    };
+                dialog = new AlertDialog.Builder( this )
+                    .setTitle( R.string.info_title )
+                    .setMessage( R.string.enable_nfc )
+                    .setPositiveButton( R.string.button_cancel, null )
+                    .setNegativeButton( R.string.button_go_settings, lstnr )
+                    .create();
+                break;
+
             default:
                 // just drop it; super.onCreateDialog likely failed
                 break;
@@ -918,10 +935,15 @@ public class BoardActivity extends XWActivity
     {
         if ( LAUNCH_INVITE_ACTION == id ) {
             if ( DlgDelegate.DISMISS_BUTTON != which ) {
+                if ( DlgDelegate.NFC_BTN == which
+                     && !NFCUtils.nfcAvail( this )[1] ) {
+                    showDialog( ENABLE_NFC );
+                } else {
                     GameUtils.launchInviteActivity( this, which,
                                                     m_room, null, m_gi.dictLang, 
                                                     m_gi.dictName, m_gi.nPlayers );
                 }
+            }
         } else if ( AlertDialog.BUTTON_POSITIVE == which ) {
             JNICmd cmd = JNICmd.CMD_NONE;
             switch ( id ) {

xwords4/android/XWords4/src/org/eehouse/android/xw4/DlgDelegate.java

@@ -229,7 +229,7 @@ public class DlgDelegate {
     public void showInviteChoicesThen( final int callbackID )
     {
         if ( Utils.deviceSupportsSMS( m_activity )
-             || NFCUtils.nfcAvail( m_activity )[1] ) {
+             || NFCUtils.nfcAvail( m_activity )[0] ) {
             DlgState state = new DlgState( INVITE_CHOICES_THEN, callbackID );
             addState( state );
             m_activity.showDialog( INVITE_CHOICES_THEN );
@@ -415,7 +415,7 @@ public class DlgDelegate {
         OnClickListener lstnr = mkCallbackClickListener( state );
 
         boolean haveSMS = Utils.deviceSupportsSMS( m_activity );
-        boolean haveNFC = NFCUtils.nfcAvail( m_activity )[1];
+        boolean haveNFC = NFCUtils.nfcAvail( m_activity )[0];
         int msgID;
         if ( haveSMS && haveNFC ) {
             msgID = R.string.nfc_or_sms_or_email;