containsSpecialChar method
Returns true
if the String contains any of the following caracters: "!@#$%?&*()-+=^;,.'"/¨{}[]¤<>°`~".
Implementation
bool containsSpecialChar() {
return characters
.any((char) => "!@#\$%?&*()-+=^;,.'\"\\/¨{}[]¤<>°`~".contains(char));
}