Millised on viis kasutada Dartis võtmesõna const…

The const keyword in Dart is used to create constant values that are determined at compile time and cannot be changed during program execution.

Usage methods:

As a variable modifier: Used to declare a variable whose value is constant at compile time.
```
const int speedOfLight = 299792458; // Constant value
```

As a constructor modifier: A constructor marked as const creates immutable class instances if all its fields are final (final) or constant (const).

class Point {
  final double x;
  final double y;

  const Point(this.x, this.y); // Constant constructor
}

const origin = Point(0.0, 0.0); // Creating a constant instance

For creating constant collections: Used to create lists, sets, and maps whose contents are constant during compilation.

const List<int> primeNumbers = [2, 3, 5, 7, 11]; // Constant list
const Set<String> constants = {'pi', 'e', 'phi'}; // Constant set
const Map<String, double> mathConstants = {
  'pi': 3.14159,
  'e': 2.71828
}; // Constant map

In contexts where a constant value is expected: For example, when creating widgets in Flutter, where constant widgets can be optimized.
```
// In Flutter context
const Text('Hello, World!'); // Constant widget
```

Differences from final:

const defines a value known at compile time.
final defines a value that is assigned only once during execution and cannot be changed afterward.

Characteristics	`const`	`final`
Initialization time	At compile time	At runtime (once)
Mutability of value	Immutable	Assigned once, then immutable
Application to instances	Creates a constant instance (if constructor is `const`)	Creates an immutable reference to an object
Application to collections	Creates an immutable collection with immutable content	Creates an immutable reference to a collection (content can be mutable)

Millised on viis kasutada Dartis võtmesõna const?