设计一个Stringl类

public final class FuckString {

    private final char[] data;

    /**
     * 构造一个字符串
     *
     * @param data 字符数组
     */
    public FuckString(final char... data) {
        this.data = null == data
                ? new char[0]
                : data.clone();
    }

    /**
     * 获取字符串长度
     *
     * @return 字符串长度
     */
    public int getLength() {
        return data.length;
    }

    // 判断两个字符数组是否相等
    private boolean isCharArrayEquals(final char[] src,
                                      final char[] dst) {
        if (src == dst) {
            return true;
        }

        if (null == src) {
            return false;
        }

        if (src.length != dst.length) {
            return false;
        }

        for (int i = 0; i < src.length; i++) {
            if (src[i] != dst[i]) {
                return false;
            }
        }

        return true;
    }

    @Override
    public boolean equals(Object obj) {
        if (null == obj) {
            return false;
        }

        if (obj instanceof FuckString) {
            return isCharArrayEquals(data, ((FuckString) obj).data);
        } else if (obj instanceof String) {
            return isCharArrayEquals(data, ((String) obj).toCharArray());
        } else {
            return false;
        }

    }

    /**
     * 转换为字符数组
     *
     * @return 字符数组
     */
    public char[] toCharArray() {
        return data.clone();
    }

    @Override
    public String toString() {
        return new String(data);
    }

    /**
     * 判断目标字符是否出现在当前字符串中
     *
     * @param targetChar 目标字符
     * @return TRUE:出现;FALSE:不出现
     */
    public boolean containChar(char targetChar) {
        for (final char c : data) {
            if (c == targetChar) {
                return true;
            }
        }
        return false;
    }


    // 随便写一些测试用例，覆盖上边的所有场景
    public static void main(String... args) {

        assertTrue(new FuckString(new char[]{'F', 'U', 'C', 'K', ' ', 'Y', 'O', 'U'}).getLength() == 8);
        assertTrue(new FuckString(null).getLength() == 0);

        assertTrue(new FuckString('F', 'U', 'C', 'K', ' ', 'Y', 'O', 'U').equals(new String("FUCK YOU")));
        assertFalse(new FuckString('F', 'U', 'C', 'K', ' ', 'Y', 'O', 'U').equals(new String("FUCK ME")));

        assertTrue(new FuckString('F', 'U', 'C', 'K', ' ', 'Y', 'O', 'U').equals(new FuckString('F', 'U', 'C', 'K', ' ', 'Y', 'O', 'U')));
        assertFalse(new FuckString('F', 'U', 'C', 'K', ' ', 'Y', 'O', 'U').equals(new FuckString('F', 'U', 'C', 'K', ' ', 'M', 'E')));

        {
            final char[] data = {'F', 'U', 'C', 'K'};
            final FuckString fString = new FuckString(data);
            data[1] = 'S';
            assertTrue(fString.equals("FUCK"));
        }

        {
            final FuckString fString = new FuckString('F', 'U', 'C', 'K');
            final char[] data = fString.toCharArray();
            data[1] = 'S';
            assertTrue(fString.equals("FUCK"));
        }

        assertTrue(new FuckString('F', 'U', 'C', 'K').toString().equals("FUCK"));
        assertTrue(new FuckString('F', 'U', 'C', 'K').containChar('U'));
        assertFalse(new FuckString('F', 'U', 'C', 'K').containChar('X'));

    }

    // 用于测试用的简单断言
    private static void assertTrue(boolean expect) {
        if (!expect) {
            throw new IllegalStateException("assert fail!");
        }
    }

    private static void assertFalse(boolean expect) {
        assertTrue(!expect);
    }

}