charAt method Null safety

String? charAt(
  1. int index
)

Returns the character at index

Example

String foo1 = 'esentis';
String char1 = foo1.charAt(0); // returns 'e'
String char2 = foo1.charAt(4); // returns 'n'
String? char3 = foo1.charAt(-20); // returns null
String? char4 = foo1.charAt(20); // returns null

Implementation

String? charAt(int index) {
  if (this == null) {
    return null;
  }
  if (this!.isEmpty) {
    return this;
  }
  if (index > this!.length) {
    return null;
  }
  if (index < 0) {
    return null;
  }
  return this!.split('')[index];
}