android - 如何在flutter中定义变量和常量？

Question

正如我们在 swift 中定义的那样

与 let 保持一致
var 的变量

如何在 flutter 中定义？

Answer 1

变量:

var number = 42;

常数:

If you never intend to change a variable, use final or const, either instead of var or in addition to a type. A final variable can be set only once; a const variable is a compile-time constant. (Const variables are implicitly final.) A final top-level or class variable is initialized the first time it’s used.

final name = 'Bob'; // Without a type annotation
final String nickname = 'Bobby';

Use const for variables that you want to be compile-time constants. If the const variable is at the class level, mark it static const. Where you declare the variable, set the value to a compile-time constant such as a number or string literal, a const variable, or the result of an arithmetic operation on constant numbers:

const bar = 1000000; // Unit of pressure (dynes/cm2)
const double atm = 1.01325 * bar; // Standard atmosphere

更多信息: https://dart.dev/guides/language/language-tour#variables