What is runtimeType Property ?

The runtimeType property is used to find out the runtime type of the object. The keyword var in Dart language lets a variable store any type of data. The runtimeType property helps to find what kind of data is stored in the variable using var keyword. In the next section, we'll explore usage of this property in for different type of data.

Usage

Let's see a few examples of using runtimeType property below. You can execute code samples in DartPad online.

The keyword var in Dart lets a variable store any type of data. Depending on what type of data is stored, it infers the data type. Calling runtimeType on the variable will return the data type of the variable.

• int: Find the type of the variable storing an integer value. An integer in dart is represented using int class.

In this examples, variable myNumber is storing an integer. Calling runtimeType on this variable will return the data type of the variable as int.

//Variable myNumber is storing an integer value
var myNumber = 1;

//myNumber.runtimeType will print the data type for the variable
print("Type of myNumber: ${myNumber.runtimeType}");

Output:

Type of myNumber: int

• String: Find the type of the variable storing a string value.

In this examples, variable myString is storing a string. Calling runtimeType on this variable will return the data type of the variable as String.

//Variable myString is storing an string value
var myString = "This is String";

//myString.runtimeType will print the data type for the variable
print("Type of myString: ${myString.runtimeType}");

Output:

Type of myString: String

• double: Find the type of the variable storing a double value.

In this examples, variable myDouble is storing a double. Calling runtimeType on this variable will return the data type of the variable as double.

//Variable myDouble is storing an string value
var myDouble = 1.0;

//myDouble.runtimeType will print the data type for the variable
print("Type of myDouble: ${myDouble.runtimeType}");

Output:

Type of myDouble: double

• List<int>: Find the type of the variable storing a list of integers.

In this examples, variable myList is storing a list of integers. Calling runtimeType on this variable will return the data type of the variable as List<int>.

//Variable myList is storing an string value
var myList = [1, 2, 3];

//myList.runtimeType will print the data type for the variable
print("Type of myList: ${myList.runtimeType}");

Output:

Type of myList: List<int>

Companion Video

Source Code

Please checkout the source code at Github here

References

1. Official Documentation for runtimeType
2. DartPad

Happy Darting :)

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