String Methods

Strings in Dart come with a powerful set of built-in methods that make text manipulation easy and efficient. Think of these methods as your toolkit for working with text - whether you need to transform, search, or extract parts of a string.

Common String Methods

Let's explore the most frequently used string methods with practical examples:

Length and Basic Properties

String message = "Hello, Dart!";
print(message.length);        // Output: 12
print(message.isEmpty);       // Output: false
print(message.isNotEmpty);    // Output: true

String empty = "";
print(empty.isEmpty);         // Output: true

Case Conversion

String text = "Hello World";
print(text.toLowerCase());    // Output: hello world
print(text.toUpperCase());    // Output: HELLO WORLD

Searching and Checking

String sentence = "Dart is awesome";

// Check if string contains substring
print(sentence.contains("Dart"));      // Output: true
print(sentence.contains("Python"));    // Output: false

// Find position of substring
print(sentence.indexOf("is"));         // Output: 5
print(sentence.indexOf("xyz"));        // Output: -1 (not found)

// Check start and end
print(sentence.startsWith("Dart"));    // Output: true
print(sentence.endsWith("awesome"));   // Output: true

Extracting Parts of Strings

String text = "Programming";

// Get substring
print(text.substring(0, 7));          // Output: Program
print(text.substring(7));             // Output: ming

// Get characters at specific positions
print(text[0]);                       // Output: P
print(text[text.length - 1]);         // Output: g

Splitting and Joining

String fruits = "apple,banana,orange";
List<String> fruitList = fruits.split(",");
print(fruitList);                     // Output: [apple, banana, orange]

// Join list back to string
String joined = fruitList.join(" - ");
print(joined);                        // Output: apple - banana - orange

Trimming Whitespace

String messy = "  Hello World  ";
print(messy.trim());                  // Output: Hello World
print(messy.trimLeft());              // Output: Hello World  
print(messy.trimRight());             // Output:   Hello World

Replacing Text

String original = "I love Java programming";
String updated = original.replaceAll("Java", "Dart");
print(updated);                       // Output: I love Dart programming

// Replace only first occurrence
String text = "cat and cat";
print(text.replaceFirst("cat", "dog")); // Output: dog and cat

Method Chaining

You can chain multiple string methods together for powerful text processing:

String input = "  HELLO WORLD  ";
String result = input.trim().toLowerCase().replaceAll(" ", "_");
print(result);                        // Output: hello_world

Practical Example

Here's a real-world example of using string methods to format a user's name:

String rawName = "  jOhN dOe  ";

String formattedName = rawName
    .trim()                           // Remove extra spaces
    .toLowerCase()                    // Convert to lowercase
    .split(" ")                       // Split into parts
    .map((part) => part[0].toUpperCase() + part.substring(1))  // Capitalize each part
    .join(" ");                       // Join back together

print(formattedName);                 // Output: John Doe

Quick Reference Table

Method	Purpose	Example
length	Get string length	"Hello".length → 5
isEmpty	Check if empty	"".isEmpty → true
toLowerCase()	Convert to lowercase	"HI".toLowerCase() → "hi"
toUpperCase()	Convert to uppercase	"hi".toUpperCase() → "HI"
contains()	Check if contains substring	"hello".contains("ell") → true
indexOf()	Find position of substring	"hello".indexOf("l") → 2
substring()	Extract part of string	"hello".substring(1, 4) → "ell"
split()	Split into list	"a,b,c".split(",") → ["a", "b", "c"]
trim()	Remove whitespace	" hi ".trim() → "hi"
replaceAll()	Replace all occurrences	"hi hi".replaceAll("hi", "bye") → "bye bye"

These string methods are your best friends when working with text in Dart. They help you clean, transform, and manipulate strings efficiently!