Are you working with Dart and need to check the data type of a variable? Checking the data type can be useful for debugging, ensuring that you’re working with the correct type of data, and preventing unexpected errors. In this tutorial, we’ll explore various methods to check the data type in Dart.
Using the ‘is’ keyword
One way to check the data type in Dart is by using the ‘is’ keyword. The ‘is’ keyword checks if an object is of a specific type. It returns true if the object is of that type, otherwise it returns false.
Here’s an example:
String name = 'John';
if (name is String) {
print('name is a String');
} else {
print('name is not a String');
}
In this example, we declare a variable ‘name’ and assign it a value of ‘John’. We then use the ‘is’ keyword to check if ‘name’ is of type String. Since it is, the code within the if block will execute and print ‘name is a String’.
Using the runtimeType property
Dart provides a runtimeType property that can be used to get the actual type of an object at runtime. This can be helpful when you need to determine the exact type of an object.
int number = 42;
print(number.runtimeType);
In this example, we declare a variable ‘number’ and assign it a value of 42. By calling .runtimeType on number, we can retrieve its data type, which in this case would be int. The output will be: int.
Using the ‘as’ keyword
The ‘as’ keyword in Dart can be used to cast an object to a specific type. If the object is not of that type, a CastError will be thrown.
dynamic value = '42';
int number = value as int;
print(number);
In this example, we declare a variable ‘value’ and assign it a value of ’42’. Since we’ve declared ‘value’ as dynamic, it can hold any type of value.
We then use the ‘as’ keyword to cast ‘value’ to type int. Since ‘value’ can be parsed as an integer, the code will execute without throwing an error and print 42.
Using reflection
Dart provides reflection capabilities through the dart:mirrors library. Reflection allows you to inspect and manipulate objects at runtime, including checking their data types.
However, reflection is more advanced and beyond the scope of this tutorial. If you’re interested in learning more about reflection in Dart, refer to the official documentation on dart:mirrors.
Summary
- The ‘is’ keyword can be used to check if an object is of a specific type.
- The runtimeType property can be used to get the actual type of an object at runtime.
- The ‘as’ keyword can be used to cast an object to a specific type.
- Reflection provides advanced capabilities for checking data types in Dart through the dart:mirrors library.
Now you have multiple methods at your disposal for checking data types in Dart. Choose the one that best suits your needs and happy coding!