https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.primitives;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.RandomAccess;
import org.checkerframework.checker.nullness.qual.Nullable;


Static utility methods pertaining to char primitives, that are not already found in either Character or Arrays. 
All the operations in this class treat char values strictly numerically; they are neither Unicode-aware nor locale-dependent. 
See the Guava User Guide article on primitive utilities.

Author:Kevin Bourrillion
Since:1.0
/**
 * Static utility methods pertaining to {@code char} primitives, that are not already found in
 * either {@link Character} or {@link Arrays}.
 *
 * <p>All the operations in this class treat {@code char} values strictly numerically; they are
 * neither Unicode-aware nor locale-dependent.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
 *
 * @author Kevin Bourrillion
 * @since 1.0
 */
@GwtCompatible(emulated = true)
public final class Chars {
  private Chars() {}

  
The number of bytes required to represent a primitive char value. 
Java 8 users: use Character.BYTES instead. 
/**
   * The number of bytes required to represent a primitive {@code char} value.
   *
   * <p><b>Java 8 users:</b> use {@link Character#BYTES} instead.
   */
  public static final int BYTES = Character.SIZE / Byte.SIZE;

  
Returns a hash code for value; equal to the result of invoking ((Character)
value).hashCode(). 
Java 8 users: use Character.hashCode(char) instead. 
Params:
  • value – a primitive char value
Returns:a hash code for the value
/**
   * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Character)
   * value).hashCode()}.
   *
   * <p><b>Java 8 users:</b> use {@link Character#hashCode(char)} instead.
   *
   * @param value a primitive {@code char} value
   * @return a hash code for the value
   */
  public static int hashCode(char value) {
    return value;
  }

  
Returns the char value that is equal to value, if possible. 
Params:
  • value – any value in the range of the char type
Throws:
Returns:the char value that equals value
/**
   * Returns the {@code char} value that is equal to {@code value}, if possible.
   *
   * @param value any value in the range of the {@code char} type
   * @return the {@code char} value that equals {@code value}
   * @throws IllegalArgumentException if {@code value} is greater than {@link Character#MAX_VALUE}
   *     or less than {@link Character#MIN_VALUE}
   */
  public static char checkedCast(long value) {
    char result = (char) value;
    checkArgument(result == value, "Out of range: %s", value);
    return result;
  }

  
Returns the char nearest in value to value. 
Params:
  • value – any long value
Returns:the same value cast to char if it is in the range of the char type, Character.MAX_VALUE if it is too large, or Character.MIN_VALUE if it is too small
/**
   * Returns the {@code char} nearest in value to {@code value}.
   *
   * @param value any {@code long} value
   * @return the same value cast to {@code char} if it is in the range of the {@code char} type,
   *     {@link Character#MAX_VALUE} if it is too large, or {@link Character#MIN_VALUE} if it is too
   *     small
   */
  public static char saturatedCast(long value) {
    if (value > Character.MAX_VALUE) {
      return Character.MAX_VALUE;
    }
    if (value < Character.MIN_VALUE) {
      return Character.MIN_VALUE;
    }
    return (char) value;
  }

  
Compares the two specified char values. The sign of the value returned is the same as that of ((Character) a).compareTo(b). 
Note for Java 7 and later: this method should be treated as deprecated; use the equivalent Character.compare method instead. 
Params:
  • a – the first char to compare
  • b – the second char to compare
Returns:a negative value if a is less than b; a positive value if a is greater than b; or zero if they are equal
/**
   * Compares the two specified {@code char} values. The sign of the value returned is the same as
   * that of {@code ((Character) a).compareTo(b)}.
   *
   * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
   * equivalent {@link Character#compare} method instead.
   *
   * @param a the first {@code char} to compare
   * @param b the second {@code char} to compare
   * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
   *     greater than {@code b}; or zero if they are equal
   */
  public static int compare(char a, char b) {
    return a - b; // safe due to restricted range
  }

  
Returns true if target is present as an element anywhere in array. 
Params:
  • array – an array of char values, possibly empty
  • target – a primitive char value
Returns:true if array[i] == target for some value of i
/**
   * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
   *
   * @param array an array of {@code char} values, possibly empty
   * @param target a primitive {@code char} value
   * @return {@code true} if {@code array[i] == target} for some value of {@code i}
   */
  public static boolean contains(char[] array, char target) {
    for (char value : array) {
      if (value == target) {
        return true;
      }
    }
    return false;
  }

  
Returns the index of the first appearance of the value target in array. 
Params:
  • array – an array of char values, possibly empty
  • target – a primitive char value
Returns:the least index i for which array[i] == target, or -1 if no such index exists.
/**
   * Returns the index of the first appearance of the value {@code target} in {@code array}.
   *
   * @param array an array of {@code char} values, possibly empty
   * @param target a primitive {@code char} value
   * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
   *     such index exists.
   */
  public static int indexOf(char[] array, char target) {
    return indexOf(array, target, 0, array.length);
  }

  // TODO(kevinb): consider making this public
  private static int indexOf(char[] array, char target, int start, int end) {
    for (int i = start; i < end; i++) {
      if (array[i] == target) {
        return i;
      }
    }
    return -1;
  }

  
Returns the start position of the first occurrence of the specified target within array, or -1 if there is no such occurrence. 
More formally, returns the lowest index i such that Arrays.copyOfRange(array,
i, i + target.length) contains exactly the same elements as target. 
Params:
  • array – the array to search for the sequence target
  • target – the array to search for as a sub-sequence of array
/**
   * Returns the start position of the first occurrence of the specified {@code target} within
   * {@code array}, or {@code -1} if there is no such occurrence.
   *
   * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
   * i, i + target.length)} contains exactly the same elements as {@code target}.
   *
   * @param array the array to search for the sequence {@code target}
   * @param target the array to search for as a sub-sequence of {@code array}
   */
  public static int indexOf(char[] array, char[] target) {
    checkNotNull(array, "array");
    checkNotNull(target, "target");
    if (target.length == 0) {
      return 0;
    }

    outer:
    for (int i = 0; i < array.length - target.length + 1; i++) {
      for (int j = 0; j < target.length; j++) {
        if (array[i + j] != target[j]) {
          continue outer;
        }
      }
      return i;
    }
    return -1;
  }

  
Returns the index of the last appearance of the value target in array. 
Params:
  • array – an array of char values, possibly empty
  • target – a primitive char value
Returns:the greatest index i for which array[i] == target, or -1 if no such index exists.
/**
   * Returns the index of the last appearance of the value {@code target} in {@code array}.
   *
   * @param array an array of {@code char} values, possibly empty
   * @param target a primitive {@code char} value
   * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
   *     such index exists.
   */
  public static int lastIndexOf(char[] array, char target) {
    return lastIndexOf(array, target, 0, array.length);
  }

  // TODO(kevinb): consider making this public
  private static int lastIndexOf(char[] array, char target, int start, int end) {
    for (int i = end - 1; i >= start; i--) {
      if (array[i] == target) {
        return i;
      }
    }
    return -1;
  }

  
Returns the least value present in array. 
Params:
  • array – a nonempty array of char values
Throws:
Returns:the value present in array that is less than or equal to every other value in the array
/**
   * Returns the least value present in {@code array}.
   *
   * @param array a <i>nonempty</i> array of {@code char} values
   * @return the value present in {@code array} that is less than or equal to every other value in
   *     the array
   * @throws IllegalArgumentException if {@code array} is empty
   */
  public static char min(char... array) {
    checkArgument(array.length > 0);
    char min = array[0];
    for (int i = 1; i < array.length; i++) {
      if (array[i] < min) {
        min = array[i];
      }
    }
    return min;
  }

  
Returns the greatest value present in array. 
Params:
  • array – a nonempty array of char values
Throws:
Returns:the value present in array that is greater than or equal to every other value in the array
/**
   * Returns the greatest value present in {@code array}.
   *
   * @param array a <i>nonempty</i> array of {@code char} values
   * @return the value present in {@code array} that is greater than or equal to every other value
   *     in the array
   * @throws IllegalArgumentException if {@code array} is empty
   */
  public static char max(char... array) {
    checkArgument(array.length > 0);
    char max = array[0];
    for (int i = 1; i < array.length; i++) {
      if (array[i] > max) {
        max = array[i];
      }
    }
    return max;
  }

  
Returns the value nearest to value which is within the closed range [min..max]. 
If value is within the range [min..max], value is returned unchanged. If value is less than min, min is returned, and if 
value is greater than max, max is returned. 
Params:
  • value – the char value to constrain
  • min – the lower bound (inclusive) of the range to constrain value to
  • max – the upper bound (inclusive) of the range to constrain value to
Throws:
Since:21.0
/**
   * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
   *
   * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
   * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
   * value} is greater than {@code max}, {@code max} is returned.
   *
   * @param value the {@code char} value to constrain
   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
   * @throws IllegalArgumentException if {@code min > max}
   * @since 21.0
   */
  @Beta
  public static char constrainToRange(char value, char min, char max) {
    checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max);
    return value < min ? min : value < max ? value : max;
  }

  
Returns the values from each provided array combined into a single array. For example, 
concat(new char[] {a, b}, new char[] {}, new char[] {c} returns the array {a, b, c}. 
Params:
  • arrays – zero or more char arrays
Returns:a single array containing all the values from the source arrays, in order
/**
   * Returns the values from each provided array combined into a single array. For example, {@code
   * concat(new char[] {a, b}, new char[] {}, new char[] {c}} returns the array {@code {a, b, c}}.
   *
   * @param arrays zero or more {@code char} arrays
   * @return a single array containing all the values from the source arrays, in order
   */
  public static char[] concat(char[]... arrays) {
    int length = 0;
    for (char[] array : arrays) {
      length += array.length;
    }
    char[] result = new char[length];
    int pos = 0;
    for (char[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);
      pos += array.length;
    }
    return result;
  }

  
Returns a big-endian representation of value in a 2-element byte array; equivalent to ByteBuffer.allocate(2).putChar(value).array(). For example, the input value 
'\\u5432' would yield the byte array {0x54, 0x32}. 
If you need to convert and concatenate several values (possibly even of different types), use a shared ByteBuffer instance, or use ByteStreams.newDataOutput() to get a growable buffer. 
/**
   * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
   * {@code ByteBuffer.allocate(2).putChar(value).array()}. For example, the input value {@code
   * '\\u5432'} would yield the byte array {@code {0x54, 0x32}}.
   *
   * <p>If you need to convert and concatenate several values (possibly even of different types),
   * use a shared {@link java.nio.ByteBuffer} instance, or use {@link
   * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
   */
  @GwtIncompatible // doesn't work
  public static byte[] toByteArray(char value) {
    return new byte[] {(byte) (value >> 8), (byte) value};
  }

  
Returns the char value whose big-endian representation is stored in the first 2 bytes of bytes; equivalent to ByteBuffer.wrap(bytes).getChar(). For example, the input byte array {0x54, 0x32} would yield the char value '\\u5432'. 
Arguably, it's preferable to use ByteBuffer; that library exposes much more flexibility at little cost in readability. 
Throws:
/**
   * Returns the {@code char} value whose big-endian representation is stored in the first 2 bytes
   * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getChar()}. For example, the
   * input byte array {@code {0x54, 0x32}} would yield the {@code char} value {@code '\\u5432'}.
   *
   * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
   * flexibility at little cost in readability.
   *
   * @throws IllegalArgumentException if {@code bytes} has fewer than 2 elements
   */
  @GwtIncompatible // doesn't work
  public static char fromByteArray(byte[] bytes) {
    checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
    return fromBytes(bytes[0], bytes[1]);
  }

  
Returns the char value whose byte representation is the given 2 bytes, in big-endian order; equivalent to Chars.fromByteArray(new byte[] {b1, b2}). 
Since:7.0
/**
   * Returns the {@code char} value whose byte representation is the given 2 bytes, in big-endian
   * order; equivalent to {@code Chars.fromByteArray(new byte[] {b1, b2})}.
   *
   * @since 7.0
   */
  @GwtIncompatible // doesn't work
  public static char fromBytes(byte b1, byte b2) {
    return (char) ((b1 << 8) | (b2 & 0xFF));
  }

  
Returns an array containing the same values as array, but guaranteed to be of a specified minimum length. If array already has a length of at least minLength, it is returned directly. Otherwise, a new array of size minLength + padding is returned, containing the values of array, and zeroes in the remaining places. 
Params:
  • array – the source array
  • minLength – the minimum length the returned array must guarantee
  • padding – an extra amount to "grow" the array by if growth is necessary
Throws:
Returns:an array containing the values of array, with guaranteed minimum length 
    minLength
/**
   * Returns an array containing the same values as {@code array}, but guaranteed to be of a
   * specified minimum length. If {@code array} already has a length of at least {@code minLength},
   * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
   * returned, containing the values of {@code array}, and zeroes in the remaining places.
   *
   * @param array the source array
   * @param minLength the minimum length the returned array must guarantee
   * @param padding an extra amount to "grow" the array by if growth is necessary
   * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
   * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
   *     minLength}
   */
  public static char[] ensureCapacity(char[] array, int minLength, int padding) {
    checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
    checkArgument(padding >= 0, "Invalid padding: %s", padding);
    return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
  }

  
Returns a string containing the supplied char values separated by separator. For example, join("-", '1', '2', '3') returns the string "1-2-3". 
Params:
  • separator – the text that should appear between consecutive values in the resulting string
    (but not at the start or end)
  • array – an array of char values, possibly empty
/**
   * Returns a string containing the supplied {@code char} values separated by {@code separator}.
   * For example, {@code join("-", '1', '2', '3')} returns the string {@code "1-2-3"}.
   *
   * @param separator the text that should appear between consecutive values in the resulting string
   *     (but not at the start or end)
   * @param array an array of {@code char} values, possibly empty
   */
  public static String join(String separator, char... array) {
    checkNotNull(separator);
    int len = array.length;
    if (len == 0) {
      return "";
    }

    StringBuilder builder = new StringBuilder(len + separator.length() * (len - 1));
    builder.append(array[0]);
    for (int i = 1; i < len; i++) {
      builder.append(separator).append(array[i]);
    }
    return builder.toString();
  }

  
Returns a comparator that compares two char arrays lexicographically; not advisable for sorting user-visible strings as the ordering may not match the conventions of the user's locale. That is, it compares, using compare(char, char)), the first pair of values that follow any common prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For example, [] < ['a'] < ['a', 'b'] < ['b']. 
The returned comparator is inconsistent with Object.equals(Object) (since arrays support only identity equality), but it is consistent with Arrays.equals(char[], char[]). 
Since:2.0
/**
   * Returns a comparator that compares two {@code char} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>; not advisable
   * for sorting user-visible strings as the ordering may not match the conventions of the user's
   * locale. That is, it compares, using {@link #compare(char, char)}), the first pair of values
   * that follow any common prefix, or when one array is a prefix of the other, treats the shorter
   * array as the lesser. For example, {@code [] < ['a'] < ['a', 'b'] < ['b']}.
   *
   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
   * support only identity equality), but it is consistent with {@link Arrays#equals(char[],
   * char[])}.
   *
   * @since 2.0
   */
  public static Comparator<char[]> lexicographicalComparator() {
    return LexicographicalComparator.INSTANCE;
  }

  private enum LexicographicalComparator implements Comparator<char[]> {
    INSTANCE;

    @Override
    public int compare(char[] left, char[] right) {
      int minLength = Math.min(left.length, right.length);
      for (int i = 0; i < minLength; i++) {
        int result = Chars.compare(left[i], right[i]);
        if (result != 0) {
          return result;
        }
      }
      return left.length - right.length;
    }

    @Override
    public String toString() {
      return "Chars.lexicographicalComparator()";
    }
  }

  
Copies a collection of Character instances into a new array of primitive char values. 
Elements are copied from the argument collection as if by collection.toArray(). Calling this method is as thread-safe as calling that method. 
Params:
  • collection – a collection of Character objects
Throws:
Returns:an array containing the same values as collection, in the same order, converted to primitives
/**
   * Copies a collection of {@code Character} instances into a new array of primitive {@code char}
   * values.
   *
   * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
   * Calling this method is as thread-safe as calling that method.
   *
   * @param collection a collection of {@code Character} objects
   * @return an array containing the same values as {@code collection}, in the same order, converted
   *     to primitives
   * @throws NullPointerException if {@code collection} or any of its elements is null
   */
  public static char[] toArray(Collection<Character> collection) {
    if (collection instanceof CharArrayAsList) {
      return ((CharArrayAsList) collection).toCharArray();
    }

    Object[] boxedArray = collection.toArray();
    int len = boxedArray.length;
    char[] array = new char[len];
    for (int i = 0; i < len; i++) {
      // checkNotNull for GWT (do not optimize)
      array[i] = (Character) checkNotNull(boxedArray[i]);
    }
    return array;
  }

  
Sorts the elements of array in descending order. 
Since:23.1
/**
   * Sorts the elements of {@code array} in descending order.
   *
   * @since 23.1
   */
  public static void sortDescending(char[] array) {
    checkNotNull(array);
    sortDescending(array, 0, array.length);
  }

  
Sorts the elements of array between fromIndex inclusive and toIndex exclusive in descending order. 
Since:23.1
/**
   * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
   * exclusive in descending order.
   *
   * @since 23.1
   */
  public static void sortDescending(char[] array, int fromIndex, int toIndex) {
    checkNotNull(array);
    checkPositionIndexes(fromIndex, toIndex, array.length);
    Arrays.sort(array, fromIndex, toIndex);
    reverse(array, fromIndex, toIndex);
  }

  
Reverses the elements of array. This is equivalent to 
Collections.reverse(Chars.asList(array)), but is likely to be more efficient. 
Since:23.1
/**
   * Reverses the elements of {@code array}. This is equivalent to {@code
   * Collections.reverse(Chars.asList(array))}, but is likely to be more efficient.
   *
   * @since 23.1
   */
  public static void reverse(char[] array) {
    checkNotNull(array);
    reverse(array, 0, array.length);
  }

  
Reverses the elements of array between fromIndex inclusive and toIndex exclusive. This is equivalent to 
Collections.reverse(Chars.asList(array).subList(fromIndex, toIndex)), but is likely to be more efficient. 
Throws:
Since:23.1
/**
   * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
   * exclusive. This is equivalent to {@code
   * Collections.reverse(Chars.asList(array).subList(fromIndex, toIndex))}, but is likely to be more
   * efficient.
   *
   * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
   *     {@code toIndex > fromIndex}
   * @since 23.1
   */
  public static void reverse(char[] array, int fromIndex, int toIndex) {
    checkNotNull(array);
    checkPositionIndexes(fromIndex, toIndex, array.length);
    for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) {
      char tmp = array[i];
      array[i] = array[j];
      array[j] = tmp;
    }
  }

  
Returns a fixed-size list backed by the specified array, similar to Arrays.asList(Object[]). The list supports List.set(int, Object), but any attempt to set a value to null will result in a NullPointerException. 
The returned list maintains the values, but not the identities, of Character objects written to or read from it. For example, whether list.get(0) == list.get(0) is true for the returned list is unspecified. 
Params:
  • backingArray – the array to back the list
Returns:a list view of the array
/**
   * Returns a fixed-size list backed by the specified array, similar to {@link
   * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
   * set a value to {@code null} will result in a {@link NullPointerException}.
   *
   * <p>The returned list maintains the values, but not the identities, of {@code Character} objects
   * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
   * the returned list is unspecified.
   *
   * @param backingArray the array to back the list
   * @return a list view of the array
   */
  public static List<Character> asList(char... backingArray) {
    if (backingArray.length == 0) {
      return Collections.emptyList();
    }
    return new CharArrayAsList(backingArray);
  }

  @GwtCompatible
  private static class CharArrayAsList extends AbstractList<Character>
      implements RandomAccess, Serializable {
    final char[] array;
    final int start;
    final int end;

    CharArrayAsList(char[] array) {
      this(array, 0, array.length);
    }

    CharArrayAsList(char[] array, int start, int end) {
      this.array = array;
      this.start = start;
      this.end = end;
    }

    @Override
    public int size() {
      return end - start;
    }

    @Override
    public boolean isEmpty() {
      return false;
    }

    @Override
    public Character get(int index) {
      checkElementIndex(index, size());
      return array[start + index];
    }

    @Override
    public boolean contains(Object target) {
      // Overridden to prevent a ton of boxing
      return (target instanceof Character)
          && Chars.indexOf(array, (Character) target, start, end) != -1;
    }

    @Override
    public int indexOf(Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Character) {
        int i = Chars.indexOf(array, (Character) target, start, end);
        if (i >= 0) {
          return i - start;
        }
      }
      return -1;
    }

    @Override
    public int lastIndexOf(Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Character) {
        int i = Chars.lastIndexOf(array, (Character) target, start, end);
        if (i >= 0) {
          return i - start;
        }
      }
      return -1;
    }

    @Override
    public Character set(int index, Character element) {
      checkElementIndex(index, size());
      char oldValue = array[start + index];
      // checkNotNull for GWT (do not optimize)
      array[start + index] = checkNotNull(element);
      return oldValue;
    }

    @Override
    public List<Character> subList(int fromIndex, int toIndex) {
      int size = size();
      checkPositionIndexes(fromIndex, toIndex, size);
      if (fromIndex == toIndex) {
        return Collections.emptyList();
      }
      return new CharArrayAsList(array, start + fromIndex, start + toIndex);
    }

    @Override
    public boolean equals(@Nullable Object object) {
      if (object == this) {
        return true;
      }
      if (object instanceof CharArrayAsList) {
        CharArrayAsList that = (CharArrayAsList) object;
        int size = size();
        if (that.size() != size) {
          return false;
        }
        for (int i = 0; i < size; i++) {
          if (array[start + i] != that.array[that.start + i]) {
            return false;
          }
        }
        return true;
      }
      return super.equals(object);
    }

    @Override
    public int hashCode() {
      int result = 1;
      for (int i = start; i < end; i++) {
        result = 31 * result + Chars.hashCode(array[i]);
      }
      return result;
    }

    @Override
    public String toString() {
      StringBuilder builder = new StringBuilder(size() * 3);
      builder.append('[').append(array[start]);
      for (int i = start + 1; i < end; i++) {
        builder.append(", ").append(array[i]);
      }
      return builder.append(']').toString();
    }

    char[] toCharArray() {
      return Arrays.copyOfRange(array, start, end);
    }

    private static final long serialVersionUID = 0;
  }
}