# StringBuilder class final

A mutable sequence of characters similar to Java's StringBuilder.

This class provides an efficient way to build strings by appending characters, strings, and other data types.

Example usage:

    StringBuilder sb = StringBuilder();
    sb.append("Hello");
    sb.append(" ");
    sb.append("World");
    sb.append("!");

    print(sb.toString()); // "Hello World!"
    print(sb.length()); // 12

## Constructors

StringBuilder.new()
  Creates an empty StringBuilder.
StringBuilder.withCapacity(int capacity)
  Creates a StringBuilder with initial capacity (ignored in Dart).
StringBuilder.withContent(String initialContent)
  Creates a StringBuilder with initial content.

## Properties

capacity → int
  Returns the current capacity (same as length in Dart).
  no setter
hashCode → int
  Returns the hash code for this StringBuilder.
  no setter override
runtimeType → Type
  A representation of the runtime type of the object.
  no setter inherited

## Methods

append(dynamic str) → StringBuilder
  Appends a string to this StringBuilder.
appendAll(Iterable<Object?> objects, [String separator = '']) → StringBuilder
  Appends all elements from an iterable.
appendBool(bool value) → StringBuilder
  Appends a boolean to this StringBuilder.
appendChar(String char) → StringBuilder
  Appends a character to this StringBuilder.
appendCharCode(int charCode) → StringBuilder
  Appends a character code.
appendDouble(double value) → StringBuilder
  Appends a double to this StringBuilder.
appendInt(int value) → StringBuilder
  Appends an integer to this StringBuilder.
appendLine([String? str]) → StringBuilder
  Appends a line separator to this StringBuilder.
appendObject(Object? obj) → StringBuilder
  Appends an object's string representation to this StringBuilder.
charAt(int index) → String
  Returns the character at the specified index.
clear() → StringBuilder
  Clears the contents of this StringBuilder.
delete(int start, int end) → StringBuilder
  Deletes characters from the specified range.
deleteCharAt(int index) → StringBuilder
  Deletes the character at the specified index.
ensureCapacity(int minimumCapacity) → void
  Ensures that the capacity is at least the specified minimum.
indexOf(String str, [int start = 0]) → int
  Returns the index of the first occurrence of the specified string.
insert(int index, String str) → StringBuilder
  Inserts a string at the specified index.
isEmpty() → bool
  Returns true if this StringBuilder is empty.
isNotEmpty() → bool
  Returns true if this StringBuilder is not empty.
lastIndexOf(String str, [int? start]) → int
  Returns the index of the last occurrence of the specified string.
length() → int
  Returns the length of this StringBuilder.
noSuchMethod(Invocation invocation) → dynamic
  Invoked when a nonexistent method or property is accessed.
  inherited
replace(int start, int end, String str) → StringBuilder
  Replaces characters in the specified range with the given string.
reverse() → StringBuilder
  Reverses the contents of this StringBuilder.
setCharAt(int index, String char) → void
  Sets the character at the specified index.
setLength(int newLength) → void
  Sets the length of this StringBuilder.
substring(int start, [int? end]) → String
  Returns a substring of this StringBuilder.
toString() → String
  Returns the string representation of this StringBuilder.
  override
trim() → StringBuilder
  Trims whitespace from the beginning and end.
trimToSize() → StringBuilder
  Trims the capacity to the current length.

## Operators

operator +(Object other) → StringBuilder
  Addition operator for appending
operator ==(Object other) → bool
  Returns true if this StringBuilder equals the specified object.
  override
operator [](int index) → String
  Operator overloads
operator []=(int index, String char) → void