Strings are immutable; methods return new strings. trim removes outer whitespace, toUpperCase converts case.

Program

Play the program to clean and uppercase a noisy greeting.

string_methods.dart
void main() {
  var text = '  Hello World  ';
  var clean = text.trim();
  var upper = clean.toUpperCase();
  print('[$upper]');
}
immutable Each method returns a fresh string; the original is unchanged.
trim Removes leading and trailing whitespace.
toUpperCase Returns an uppercase copy.