Decapitalizes the first letter of a string.

Use String.toLowerCase() to decapitalize first letter and String.toUpperCase() to convert the rest of the string to uppercase, if necessary.
Omit the optional parameter, upperRest, to keep the rest of the string intact, or set it to true to convert to uppercase.

代码实现

String capitalize(String str, {bool upperRest = false}) {
  return str[0].toUpperCase() +
      (upperRest ? str.substring(1).toLowerCase() : str.substring(1));
}

使用样例

capitalize('FooBar'); // 'fooBar'
capitalize('FooBar', upperRest: true); // 'fOOBAR'