thirdStringAtIndex method Null safety

  1. @override
String? thirdStringAtIndex(
  1. int index
)
override

第三列选中字符串

Implementation

@override
String? thirdStringAtIndex(int index) {
  if (index >= 0 && index < thirdList.length) {
    return thirdList[index];
  } else {
    return null;
  }
}