string.java

gcc的组建

   * @throws NullPointerException if the given StringBuffer is null
   * @since 1.4
   */
  public boolean contentEquals(StringBuffer buffer)
  {
    synchronized (buffer)
      {
        if (count != buffer.count)
          return false;
        if (value == buffer.value)
          return true; // Possible if shared.
        int i = count;
        int x = offset + count;
        while (--i >= 0)
          if (value[--x] != buffer.value[i])
            return false;
        return true;
      }
  }

  /**
   * Compares the given CharSequence to this String. This is true if
   * the CharSequence has the same content as this String at this
   * moment.
   *
   * @param seq the CharSequence to compare to
   * @return true if CharSequence has the same character sequence
   * @throws NullPointerException if the given CharSequence is null
   * @since 1.5
   */
  public boolean contentEquals(CharSequence seq)
  {
    if (seq.length() != count)
      return false;
    for (int i = 0; i < count; ++i)
      if (value[offset + i] != seq.charAt(i))
	return false;
    return true;
  }

  /**
   * Compares a String to this String, ignoring case. This does not handle
   * multi-character capitalization exceptions; instead the comparison is
   * made on a character-by-character basis, and is true if:<br><ul>
   * <li><code>c1 == c2</code></li>
   * <li><code>Character.toUpperCase(c1)
   *     == Character.toUpperCase(c2)</code></li>
   * <li><code>Character.toLowerCase(c1)
   *     == Character.toLowerCase(c2)</code></li>
   * </ul>
   *
   * @param anotherString String to compare to this String
   * @return true if anotherString is equal, ignoring case
   * @see #equals(Object)
   * @see Character#toUpperCase(char)
   * @see Character#toLowerCase(char)
   */
  public boolean equalsIgnoreCase(String anotherString)
  {
    if (anotherString == null || count != anotherString.count)
      return false;
    int i = count;
    int x = offset;
    int y = anotherString.offset;
    while (--i >= 0)
      {
        char c1 = value[x++];
        char c2 = anotherString.value[y++];
        // Note that checking c1 != c2 is redundant, but avoids method calls.
        if (c1 != c2
            && Character.toUpperCase(c1) != Character.toUpperCase(c2)
            && Character.toLowerCase(c1) != Character.toLowerCase(c2))
          return false;
      }
    return true;
  }

  /**
   * Compares this String and another String (case sensitive,
   * lexicographically). The result is less than 0 if this string sorts
   * before the other, 0 if they are equal, and greater than 0 otherwise.
   * After any common starting sequence is skipped, the result is
   * <code>this.charAt(k) - anotherString.charAt(k)</code> if both strings
   * have characters remaining, or
   * <code>this.length() - anotherString.length()</code> if one string is
   * a subsequence of the other.
   *
   * @param anotherString the String to compare against
   * @return the comparison
   * @throws NullPointerException if anotherString is null
   */
  public int compareTo(String anotherString)
  {
    int i = Math.min(count, anotherString.count);
    int x = offset;
    int y = anotherString.offset;
    while (--i >= 0)
      {
        int result = value[x++] - anotherString.value[y++];
        if (result != 0)
          return result;
      }
    return count - anotherString.count;
  }

  /**
   * Behaves like <code>compareTo(java.lang.String)</code> unless the Object
   * is not a <code>String</code>.  Then it throws a
   * <code>ClassCastException</code>.
   *
   * @param o the object to compare against
   * @return the comparison
   * @throws NullPointerException if o is null
   * @throws ClassCastException if o is not a <code>String</code>
   * @since 1.2
   */
  public int compareTo(Object o)
  {
    return compareTo((String) o);
  }

  /**
   * Compares this String and another String (case insensitive). This
   * comparison is <em>similar</em> to equalsIgnoreCase, in that it ignores
   * locale and multi-characater capitalization, and compares characters
   * after performing
   * <code>Character.toLowerCase(Character.toUpperCase(c))</code> on each
   * character of the string. This is unsatisfactory for locale-based
   * comparison, in which case you should use {@link java.text.Collator}.
   *
   * @param str the string to compare against
   * @return the comparison
   * @see Collator#compare(String, String)
   * @since 1.2
   */
  public int compareToIgnoreCase(String str)
  {
    int i = Math.min(count, str.count);
    int x = offset;
    int y = str.offset;
    while (--i >= 0)
      {
        int result = Character.toLowerCase(Character.toUpperCase(value[x++]))
          - Character.toLowerCase(Character.toUpperCase(str.value[y++]));
        if (result != 0)
          return result;
      }
    return count - str.count;
  }  

  /**
   * Predicate which determines if this String matches another String
   * starting at a specified offset for each String and continuing
   * for a specified length. Indices out of bounds are harmless, and give
   * a false result.
   *
   * @param toffset index to start comparison at for this String
   * @param other String to compare region to this String
   * @param ooffset index to start comparison at for other
   * @param len number of characters to compare
   * @return true if regions match (case sensitive)
   * @throws NullPointerException if other is null
   */
  public boolean regionMatches(int toffset, String other, int ooffset, int len)
  {
    return regionMatches(false, toffset, other, ooffset, len);
  }

  /**
   * Predicate which determines if this String matches another String
   * starting at a specified offset for each String and continuing
   * for a specified length, optionally ignoring case. Indices out of bounds
   * are harmless, and give a false result. Case comparisons are based on
   * <code>Character.toLowerCase()</code> and
   * <code>Character.toUpperCase()</code>, not on multi-character
   * capitalization expansions.
   *
   * @param ignoreCase true if case should be ignored in comparision
   * @param toffset index to start comparison at for this String
   * @param other String to compare region to this String
   * @param ooffset index to start comparison at for other
   * @param len number of characters to compare
   * @return true if regions match, false otherwise
   * @throws NullPointerException if other is null
   */
  public boolean regionMatches(boolean ignoreCase, int toffset,
                               String other, int ooffset, int len)
  {
    if (toffset < 0 || ooffset < 0 || toffset + len > count
        || ooffset + len > other.count)
      return false;
    toffset += offset;
    ooffset += other.offset;
    while (--len >= 0)
      {
        char c1 = value[toffset++];
        char c2 = other.value[ooffset++];
        // Note that checking c1 != c2 is redundant when ignoreCase is true,
        // but it avoids method calls.
        if (c1 != c2
            && (! ignoreCase
                || (Character.toLowerCase(c1) != Character.toLowerCase(c2)
                    && (Character.toUpperCase(c1)
                        != Character.toUpperCase(c2)))))
          return false;
      }
    return true;
  }

  /**
   * Predicate which determines if this String contains the given prefix,
   * beginning comparison at toffset. The result is false if toffset is
   * negative or greater than this.length(), otherwise it is the same as
   * <code>this.substring(toffset).startsWith(prefix)</code>.
   *
   * @param prefix String to compare
   * @param toffset offset for this String where comparison starts
   * @return true if this String starts with prefix
   * @throws NullPointerException if prefix is null
   * @see #regionMatches(boolean, int, String, int, int)
   */
  public boolean startsWith(String prefix, int toffset)
  {
    return regionMatches(false, toffset, prefix, 0, prefix.count);
  }

  /**
   * Predicate which determines if this String starts with a given prefix.
   * If the prefix is an empty String, true is returned.
   *
   * @param prefix String to compare
   * @return true if this String starts with the prefix
   * @throws NullPointerException if prefix is null
   * @see #startsWith(String, int)
   */
  public boolean startsWith(String prefix)
  {
    return regionMatches(false, 0, prefix, 0, prefix.count);
  }

  /**
   * Predicate which determines if this String ends with a given suffix.
   * If the suffix is an empty String, true is returned.
   *
   * @param suffix String to compare
   * @return true if this String ends with the suffix
   * @throws NullPointerException if suffix is null
   * @see #regionMatches(boolean, int, String, int, int)
   */
  public boolean endsWith(String suffix)
  {
    return regionMatches(false, count - suffix.count, suffix, 0, suffix.count);
  }

  /**
   * Computes the hashcode for this String. This is done with int arithmetic,
   * where ** represents exponentiation, by this formula:<br>
   * <code>s[0]*31**(n-1) + s[1]*31**(n-2) + ... + s[n-1]</code>.
   *
   * @return hashcode value of this String
   */
  public int hashCode()
  {
    if (cachedHashCode != 0)
      return cachedHashCode;

    // Compute the hash code using a local variable to be reentrant.
    int hashCode = 0;
    int limit = count + offset;
    for (int i = offset; i < limit; i++)
      hashCode = hashCode * 31 + value[i];
    return cachedHashCode = hashCode;
  }

  /**
   * Finds the first instance of a character in this String.
   *
   * @param ch character to find
   * @return location (base 0) of the character, or -1 if not found
   */
  public int indexOf(int ch)
  {
    return indexOf(ch, 0);
  }

  /**
   * Finds the first instance of a character in this String, starting at
   * a given index.  If starting index is less than 0, the search
   * starts at the beginning of this String.  If the starting index
   * is greater than the length of this String, -1 is returned.
   *
   * @param ch character to find
   * @param fromIndex index to start the search
   * @return location (base 0) of the character, or -1 if not found
   */
  public int indexOf(int ch, int fromIndex)
  {
    if ((char) ch != ch)
      return -1;
    if (fromIndex < 0)
      fromIndex = 0;
    int i = fromIndex + offset;
    for ( ; fromIndex < count; fromIndex++)
      if (value[i++] == ch)
        return fromIndex;
    return -1;
  }

  /**
   * Finds the last instance of a character in this String.
   *
   * @param ch character to find
   * @return location (base 0) of the character, or -1 if not found
   */
  public int lastIndexOf(int ch)
  {
    return lastIndexOf(ch, count - 1);
  }

  /**
   * Finds the last instance of a character in this String, starting at
   * a given index.  If starting index is greater than the maximum valid
   * index, then the search begins at the end of this String.  If the
   * starting index is less than zero, -1 is returned.
   *
   * @param ch character to find
   * @param fromIndex index to start the search
   * @return location (base 0) of the character, or -1 if not found
   */
  public int lastIndexOf(int ch, int fromIndex)
  {
    if ((char) ch != ch)
      return -1;
    if (fromIndex >= count)
      fromIndex = count - 1;
    int i = fromIndex + offset;
    for ( ; fromIndex >= 0; fromIndex--)
      if (value[i--] == ch)
        return fromIndex;
    return -1;
  }

  /**
   * Finds the first instance of a String in this String.
   *
   * @param str String to find
   * @return location (base 0) of the String, or -1 if not found
   * @throws NullPointerException if str is null
   */
  public int indexOf(String str)
  {
    return indexOf(str, 0);
  }

  /**
   * Finds the first instance of a String in this String, starting at
   * a given index.  If starting index is less than 0, the search
   * starts at the beginning of this String.  If the starting index
   * is greater than the length of this String, -1 is returned.
   *
   * @param str String to find
   * @param fromIndex index to start the search
   * @return location (base 0) of the String, or -1 if not found
   * @throws NullPointerException if str is null
   */
  public int indexOf(String str, int fromIndex)
  {
    if (fromIndex < 0)
      fromIndex = 0;
    int limit = count - str.count;
    for ( ; fromIndex <= limit; fromIndex++)
      if (regionMatches(fromIndex, str, 0, str.count))
        return fromIndex;
    return -1;
  }

  /**
   * Finds the last instance of a String in this String.
   *
   * @param str String to find
   * @return location (base 0) of the String, or -1 if not found
   * @throws NullPointerException if str is null
   */
  public int lastIndexOf(String str)