FocusNode textSecondFocusNode = new FocusNode();
TextFormField textFirst = new TextFormField(
onFieldSubmitted: (String value) {
FocusScope.of(context).requestFocus(textSecondFocusNode);
},
);
TextFormField textSecond = new TextFormField(
focusNode: textSecondFocusNode,
);
// render textFirst and textSecond where you want