Dart Literals
Fixed values in Dart code
💎 What are Dart Literals?
Literals in Dart are fixed values written directly in your code. They represent actual data like numbers, strings, booleans, and collections that don't change during compilation.
// Literal examples
int age = 25; // Number literal
String name = 'Bob'; // String literal
bool isActive = true; // Boolean literal
Types of Literals
Number Literals
Integer and double values
int count = 42;
double price = 19.99;String Literals
Text values in quotes
String message = 'Hello';
String text = "World";Boolean Literals
True or false values
bool isReady = true;
bool isComplete = false;Collection Literals
Lists, sets, and maps
List numbers = [1, 2, 3];
Map person = {'name': 'Alice'};🔹 Number Literals
Different ways to write numeric values:
// Integer literals
int decimal = 42;
int hexadecimal = 0x2A; // 42 in hex
int binary = 0b101010; // 42 in binary
int octal = 0o52; // 42 in octal
// Double literals
double simple = 3.14;
double scientific = 1.23e4; // 12300.0
double negative = -45.67;
// Large numbers with underscores for readability
int million = 1_000_000;
double precise = 3.141_592_653;
print('Decimal: $decimal');
print('Hex: $hexadecimal');
print('Binary: $binary');
print('Scientific: $scientific');
print('Million: $million');Output:
Decimal: 42
Hex: 42
Binary: 42
Scientific: 12300.0
Million: 1000000
Hex: 42
Binary: 42
Scientific: 12300.0
Million: 1000000
🔹 String Literals
Various ways to create string literals:
// Single and double quotes
String single = 'Hello World';
String double = "Hello World";
// Multi-line strings
String multiLine = '''
This is a
multi-line
string literal
''';
// Raw strings (no escape sequences)
String rawString = r'This is a raw string with \n and \t';
// String with escape sequences
String escaped = 'Line 1\nLine 2\tTabbed text';
// Unicode characters
String unicode = 'Dart is fun! 🎯';
print('Single: $single');
print('Multi-line: $multiLine');
print('Raw: $rawString');
print('Escaped: $escaped');
print('Unicode: $unicode');Output:
Single: Hello World
Multi-line:
This is a
multi-line
string literal
Raw: This is a raw string with \n and \t
Escaped: Line 1
Line 2 Tabbed text
Unicode: Dart is fun! 🎯
Multi-line:
This is a
multi-line
string literal
Raw: This is a raw string with \n and \t
Escaped: Line 1
Line 2 Tabbed text
Unicode: Dart is fun! 🎯
🔹 Collection Literals
Creating collections with literal syntax:
// List literals
List<int> numbers = [1, 2, 3, 4, 5];
List<String> fruits = ['apple', 'banana', 'orange'];
List<dynamic> mixed = [1, 'hello', true, 3.14];
// Set literals
Set<String> colors = {'red', 'green', 'blue'};
Set<int> uniqueNumbers = {1, 2, 3, 2, 1}; // Duplicates removed
// Map literals
Map<String, int> ages = {
'Alice': 25,
'Bob': 30,
'Charlie': 35
};
Map<String, dynamic> person = {
'name': 'John',
'age': 28,
'isStudent': false,
'grades': [85, 90, 78]
};
print('Numbers: $numbers');
print('Colors: $colors');
print('Unique numbers: $uniqueNumbers');
print('Ages: $ages');
print('Person: $person');Output:
Numbers: [1, 2, 3, 4, 5]
Colors: {red, green, blue}
Unique numbers: {1, 2, 3}
Ages: {Alice: 25, Bob: 30, Charlie: 35}
Person: {name: John, age: 28, isStudent: false, grades: [85, 90, 78]}
Colors: {red, green, blue}
Unique numbers: {1, 2, 3}
Ages: {Alice: 25, Bob: 30, Charlie: 35}
Person: {name: John, age: 28, isStudent: false, grades: [85, 90, 78]}
🔹 Special Literals
Special literal values in Dart:
// Null literal
String? nullableString = null;
int? nullableInt = null;
// Symbol literals
Symbol symbol1 = #mySymbol;
Symbol symbol2 = Symbol('anotherSymbol');
// Rune literals (Unicode code points)
Runes heart = Runes('\u2665'); // ♥
Runes smiley = Runes('\u{1f600}'); // 😀
// Empty collections
List<String> emptyList = [];
Set<int> emptySet = <int>{};
Map<String, int> emptyMap = {};
print('Null string: $nullableString');
print('Symbol: $symbol1');
print('Heart: ${String.fromCharCodes(heart)}');
print('Smiley: ${String.fromCharCodes(smiley)}');
print('Empty list: $emptyList');
print('Empty set: $emptySet');
print('Empty map: $emptyMap');Output:
Null string: null
Symbol: Symbol("mySymbol")
Heart: ♥
Smiley: 😀
Empty list: []
Empty set: {}
Empty map: {}
Symbol: Symbol("mySymbol")
Heart: ♥
Smiley: 😀
Empty list: []
Empty set: {}
Empty map: {}
🔹 Literal Best Practices
Tips for using literals effectively:
Performance Tips:
- Use const: Make literals const when possible for better performance
- Type annotations: Specify types for better optimization
- Avoid large literals: Consider loading large data from files
Readability Tips:
- Use underscores: Make large numbers readable (1_000_000)
- Multi-line strings: Use triple quotes for long text
- Meaningful names: Assign literals to well-named variables
// Good practices
const int maxUsers = 1_000_000;
const List<String> supportedFormats = ['jpg', 'png', 'gif'];
const Map<String, String> errorMessages = {
'network': 'Network connection failed',
'timeout': 'Request timed out',
'invalid': 'Invalid input provided'
};
// Using the constants
print('Max users: $maxUsers');
print('Supported: $supportedFormats');
print('Error: ${errorMessages['network']}');Output:
Max users: 1000000
Supported: [jpg, png, gif]
Error: Network connection failed
Supported: [jpg, png, gif]
Error: Network connection failed