For eg: Future<String?> _getDatabasePath() ? what will be the result when i give “_getDatabasePath.runtimeType” ? answer is () => Future<String?>

Overview

When you use

_getDatabasePath.runtimeType

The Example

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Future<String?> _getDatabasePath() async {
  // returns a Future<String?>
  return '/data/databases/mydb.sqlite';
}

runtimeType of the Function Reference

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// _getDatabasePath is a reference to the function itself
print(_getDatabasePath.runtimeType);
// Output: () => Future<String?>

The

runtimeType

() => Future<String?>

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  ()

  — takes no arguments
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  => Future<String?>

  — returns a Future that wraps a nullable String

Calling the Function vs Referencing It

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// 1. Calling the function — executes and returns a Future<String?>
final result = await _getDatabasePath(); // result is String?
print(result.runtimeType); // String (or Null if null)

// 2. Referencing the function — does NOT call it
print(_getDatabasePath.runtimeType); // () => Future<String?>

// 3. Calling and checking Future type
final future = _getDatabasePath(); // Not awaited — still a Future
print(future.runtimeType); // Future<String?>

Summary Table

_getDatabasePath

() => Future<String?>

_getDatabasePath()

Future<String?>

await _getDatabasePath()

String?

String

Null

Why Is This Useful?

Understanding

runtimeType

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// Checking if something is a function type
void execute(dynamic fn) {
  print(fn.runtimeType); // See signature before calling
  if (fn is Function) {
    fn();
  }
}

// Common in callbacks and higher-order functions
final void Function() callback = () => print('done');
print(callback.runtimeType); // () => void

Key Point:

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runtimeType

on a function reference shows the function's type signature. Only after you call and await it do you get the actual returned value's type.