The dynamic and Object Types
Understand Dart's top types and when they fit.
The dynamic and Object Types is a free Dart Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Dart Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Dart Has Top Types Too
Sometimes you need a variable that can hold any value. Dart offers two such top types: Object and dynamic.
Object Holds Anything Safely
An Object can store any non-null value, but Dart still checks every method call against the Object type.
Object thing = 42;
thing = "now text";Object Restricts Methods
With Object, you only get methods all values share, like toString. You must cast before using type-specific behavior.
Object o = "hi";
// o.toUpperCase(); // errordynamic Disables Checks
A dynamic variable also holds anything, but it turns off compile-time checks. Mistakes surface only at run time.
dynamic d = "hi";
d.toUpperCase(); // alloweddynamic Can Crash Late
Because checks are off, a wrong call on a dynamic compiles fine but may throw while running. Convenience has a cost.
dynamic d = 5;
d.toUpperCase(); // runtime errorObject Is Safer Than dynamic
Prefer Object when you truly need any value. You keep type safety and let the compiler guard your calls.
Object Versus Object Question
Plain Object excludes null. If a value might be null, use the nullable form Object so null is allowed too.
Object? maybe = null;Casting Back to a Type
Pull a real type out of an Object with the as cast, then call its methods with full checking restored.
Object o = "hi";
var up = (o as String).toUpperCase();Why dynamic Still Exists
dynamic helps when interacting with untyped data, like loosely shaped JSON, where the structure is unknown ahead of time.
Avoid dynamic by Default
Reaching for dynamic often hides bugs until users hit them. Use specific types or Object unless you truly need it.
Choosing Between the Two
Need any value with safety? Pick Object. Need to bypass checks for messy data? Use dynamic, sparingly and on purpose.
Quick Check
What is the key difference between Object and dynamic?
Recap: dynamic and Object
You learned Object holds anything with safety, while dynamic holds anything but skips checks. Prefer Object or specific types. 🛡️
Frequently asked questions
Is the “The dynamic and Object Types” lesson free?
Yes — the full text of “The dynamic and Object Types” is free to read here on the web, and the Dart Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Dart Academy course, upgrade to CoddyKit PRO.
What will I learn in “The dynamic and Object Types”?
Understand Dart's top types and when they fit. You practise Dart Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Dart Academy?
No prior experience is required. Dart Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “The dynamic and Object Types” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Dart Academy lesson?
Yes. Every Dart Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- var, final, and const Explained
- The Core Types: int, double, String, bool
- Type Inference vs Explicit Types
- The dynamic and Object Types