Compukters Core/kotlin.text/StringBuilder

StringBuilder

class StringBuilder(capacity: Int = 16) : CharSequence(source)

Builds mutable text by appending UTF-16 code units.

length counts code units, so a supplementary Unicode character occupies two indexes. Capacity is the allocated buffer size, not the content length. clear retains that buffer; toString and subSequence return independent immutable snapshots. Buffer growth and snapshots are subject to the Guest heap quota.

Parameters

capacity

initial buffer size in UTF-16 code units; defaults to 16.

See also

Throws

IllegalArgumentException

if capacity is negative.

Constructors

constructor(capacity: Int = 16)

Creates an empty builder with the requested initial capacity.

Properties

open override val length: Int

Number of UTF-16 code units currently stored, excluding unused capacity.

Functions

fun append(value: Any?): StringBuilder

Converts value to text and appends that text.

fun append(value: Char): StringBuilder

Appends one UTF-16 code unit, growing the buffer if needed.

fun append(value: CharArray): StringBuilder

fun append(value: CharSequence?): StringBuilder

Copies all code units from value to the end of this builder.

fun append(value: CharSequence?, startIndex: Int, endIndex: Int): StringBuilder

Copies a range of value to the end of this builder.

fun appendLine(): StringBuilder

Appends a line feed (\n).

fun appendLine(value: Any?): StringBuilder

Converts value to text, appends it, then appends a line feed (\n).

fun appendLine(value: Char): StringBuilder

Appends value followed by a line feed (\n).

fun appendLine(value: CharSequence?): StringBuilder

Copies value followed by a line feed (\n). Null appends null before the line feed.

fun appendRange(value: CharArray, startIndex: Int, endIndex: Int): StringBuilder

Copies a range of value to the end of this builder.

fun capacity(): Int

Returns the number of UTF-16 code units the buffer can hold without growing.

fun clear(): StringBuilder

Removes all content while retaining the allocated capacity for reuse.

fun CharSequence.contains(char: Char): Boolean

Returns whether this string contains char.

fun CharSequence.contains(other: CharSequence): Boolean

fun CharSequence.drop(n: Int): CharSequence

fun CharSequence.dropLast(n: Int): CharSequence

fun CharSequence.endsWith(suffix: CharSequence): Boolean

fun ensureCapacity(minimumCapacity: Int)

Grows the buffer when minimumCapacity exceeds the current capacity.

open operator override fun get(index: Int): Char

Reads a UTF-16 code unit at index.

fun CharSequence.indexOf(char: Char, startIndex: Int = 0): Int

Finds the first matching character at or after startIndex, clamped to zero.

fun CharSequence.indexOf(other: String, startIndex: Int = 0): Int

fun CharSequence.isBlank(): Boolean

Returns whether this character sequence is empty or contains only whitespace.

fun CharSequence.isEmpty(): Boolean

Returns whether this character sequence contains no characters.

fun CharSequence.isNotBlank(): Boolean

Returns whether this character sequence contains a non-whitespace character.

fun CharSequence.isNotEmpty(): Boolean

Returns whether this character sequence contains at least one character.

operator fun CharSequence.iterator(): CharIterator

Visits UTF-16 code units in order. Stored iterators are supported and own their position.

fun CharSequence.lastIndexOf(char: Char): Int

Finds the last matching character.

fun CharSequence.lastIndexOf(string: String): Int

Finds the last matching substring, starting at the last character.

fun CharSequence.lastIndexOf(char: Char, startIndex: Int): Int

Searches backwards from startIndex for char.

fun CharSequence.lastIndexOf(string: String, startIndex: Int): Int

Searches backwards from startIndex for string, comparing UTF-16 code units.

fun CharSequence.lines(): List<String>

Splits on CRLF, LF or CR, retaining empty lines including the final line.

fun CharSequence.padEnd(length: Int): CharSequence

fun CharSequence.padEnd(length: Int, padChar: Char): CharSequence

fun CharSequence.padStart(length: Int): CharSequence

fun CharSequence.padStart(length: Int, padChar: Char): CharSequence

fun CharSequence.removePrefix(prefix: CharSequence): CharSequence

fun CharSequence.removeSuffix(suffix: CharSequence): CharSequence

Removes suffix when present, otherwise returns this string.

fun CharSequence.repeat(n: Int): String

operator fun set(index: Int, value: Char)

Replaces one UTF-16 code unit without changing the content length.

fun setLength(newLength: Int)

Changes the content length, growing the buffer if needed.

fun CharSequence.split(delimiter: Char, limit: Int = 0): List<String>

Splits on delimiter, retaining empty parts. Zero limit means no limit; positive limit keeps the remaining suffix.

fun CharSequence.split(delimiter: String, limit: Int = 0): List<String>

Splits on delimiter, retaining empty parts. An empty delimiter separates UTF-16 code units, including empty ends.

fun CharSequence.startsWith(prefix: CharSequence): Boolean

open override fun subSequence(startIndex: Int, endIndex: Int): String

Copies the selected range into an immutable String.

fun CharSequence.substring(startIndex: Int): String

fun CharSequence.substring(startIndex: Int, endIndex: Int): String

Materializes the selected UTF-16 range as an immutable String.

fun CharSequence.take(n: Int): CharSequence

Counts and indexes refer to UTF-16 code units, including individual surrogate halves.

fun CharSequence.takeLast(n: Int): CharSequence

open override fun toString(): String

Copies the current content into an immutable String.

fun CharSequence.trim(): CharSequence

Removes leading and trailing whitespace.

fun CharSequence.trimEnd(): CharSequence

Removes trailing whitespace.

fun CharSequence.trimStart(): CharSequence

Removes leading whitespace.