var original = "this is a string";
var changed = original.substring(0, 1).toUpperCase() + original.substring(1);

final helloWorld = 'hello world'.toUpperCase(); 文本(helloWorld);

检查空字符串大小写，同样使用短符号:

  String capitalizeFirstLetter(String s) =>
  (s?.isNotEmpty ?? false) ? '${s[0].toUpperCase()}${s.substring(1)}' : s;

如果您使用get: ^4.6.5作为flutter的状态管理，则有用于大写的内置扩展

        // This will capitalize first letter of every word
        print('hello world'.capitalize); // Hello World

        // This will capitalize first letter of sentence
        print('hello world'.capitalizeFirst); // Hello world

        // This will remove all white spaces from sentence
        print('hello world'.removeAllWhitespace); // helloworld

        // This will convert string to lowerCamelCase
        print('This is new world'.camelCase); // thisIsNewWorld

        // This will remove all white spaces between the two words and replace it with '-'
        print('This is new    world'.paramCase); // this-is-new-world

这个代码适用于我。

String name = 'amina';    

print(${name[0].toUpperCase()}${name.substring(1).toLowerCase()});

截至2021年3月23日，Flutter 2.0.2

只需使用yourtext.capitalizeFirst