Basic

Variable

var name = 'Bob';
// or
String name = 'Bob';

Follows the style guide recommendation of using var, rather than type annotations, for local variables.

Null safety

Variables can’t contain null unless you say they can.

// x can be null.
int? x;
// You must initialize the values of non-nullable variables before you use them.
int y = 0;

You don’t have to initialize a local variable where it’s declared, but you do need to assign it a value before it’s used.

Final and const

• A final variable can be set only once.

• A const variable is a compile-time constant.

Const variables are implicitly final.

Although a final object cannot be modified, its fields can be changed. In comparison, a const object and its fields cannot be changed: they’re immutable.

Late variables

There has two use cases:

• Declaring a non-nullable variable that’s initialized after its declaration.

• Lazily initializing a variable.