Question 1

What is the difference between var and dynamic in Dart?

Accepted Answer

var determines the type at compile time based on the assigned value and remains fixed afterwards, while dynamic allows changing the type at any moment during runtime. Using var when the type is known provides better type safety and optimal performance as the compiler can perform static checks.

Question 2

What is the difference between const and final in Dart?

Accepted Answer

final allows assigning a value only once, but this value can be determined at runtime. const creates a compile-time constant whose value must be known before execution. const is more restrictive and enables additional optimizations as const objects are canonicalized and shared in memory.

Question 3

What does the ? suffix mean in a Dart type like String?

Accepted Answer

The ? suffix indicates that a variable can contain null in addition to its normal value. This is the foundation of null safety introduced in Dart 2.12. Without this suffix, the variable can never be null, eliminating NullPointerExceptions at compile time. This approach ensures null errors are detected before execution.

Dart Basics

What is the difference between var and dynamic in Dart?

Câu trả lời

What is the difference between const and final in Dart?

Câu trả lời

What does the ? suffix mean in a Dart type like String?

Câu trả lời

Which operator should be used to safely access a property of a potentially null object?

What does the ?? operator do in Dart?

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