String

// 字符串转char
public char[] toCharArray() {
        return isLatin1() ? StringLatin1.toChars(value)
                          : StringUTF16.toChars(value);
    }

// 忽略大小写比较
public boolean equalsIgnoreCase(String anotherString) {
        return (this == anotherString) ? true
                : (anotherString != null)
                && (anotherString.length() == length())
                && regionMatches(true, 0, anotherString, 0, length());
    }

// 判断长度为空  since 1.6
public boolean isEmpty() {
        return value.length == 0;
    }

/** todo 截取字符串长度，从零坐标开始，左闭右开
     * Returns a new {@code String} that contains a subsequence of
     * characters currently contained in this sequence. The
     * substring begins at the specified {@code start} and
     * extends to the character at index {@code end - 1}.
     *
     * @param      start    The beginning index, inclusive.
     * @param      end      The ending index, exclusive.
     * @return     The new string.
     * @throws     StringIndexOutOfBoundsException  if {@code start}
     *             or {@code end} are negative or greater than
     *             {@code length()}, or {@code start} is
     *             greater than {@code end}.
     */
    public String substring(int start, int end) {
        checkRangeSIOOBE(start, end, count);
        if (isLatin1()) {
            return StringLatin1.newString(value, start, end - start);
        }
        return StringUTF16.newString(value, start, end - start);
    }