JAVA Code:

public class HexUtils {/** * 十六进制String转换成Byte[] * @param hexString the hex string * @return byte[] */public static byte[] hexStringToBytes(String hexString) {if (hexString == null || hexString.equals("")) {return null;}hexString = hexString.toUpperCase();int length = hexString.length() / 2;char[] hexChars = hexString.toCharArray();byte[] d = new byte[length];for (int i = 0; i < length; i++) {int pos = i * 2;d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));}return d;}/** * Convert char to byte * @param c char * @return byte */private static byte charToByte(char c) {return (byte) "0123456789ABCDEF".indexOf(c);}/* 这里我们可以将byte转换成int，然后利用Integer.toHexString(int)来转换成16进制字符串。 * @param src byte[] data * @return hex string */public static String bytesToHexString(byte[] src){StringBuilder stringBuilder = new StringBuilder("");if (src == null || src.length <= 0) {return null;}for (int i = 0; i < src.length; i++) {int v = src[i] & 0xFF;String hv = Integer.toHexString(v);if (hv.length() < 2) {stringBuilder.append(0);}stringBuilder.append(hv);}return stringBuilder.toString();}

这段代码在Java上使用或者kotlin引用都不会出现问题的，但现在Google宣布Kotlin成安卓官方语言，所以很多人都会将之前Java代码转成kotlin，如果是把Java代码直接通 studiog工具栏Code->Convert java File to Kotlin 生成kotlin代码，则会报以下的错误

这两个地方的出错都是由于kotlin位运算符只适用于Int 和 Long,所以先将shl ，and 前面的值转成Int 类型再执行shl ,and 等运算。Kotlin中每个数字类型支持如下的转换:

• toByte(): Byte
• toShort(): Short
• toInt(): Int
• toLong(): Long
• toFloat(): Float
• toDouble(): Double
• toChar(): Char

Kotlin Code

object HexUtils {/*** 十六进制String转换成Byte[]* @param hexString the hex string* ** @return byte[]*/fun hexStringToBytes(hexString: String?): ByteArray? {var hexString = hexStringif (hexString == null || hexString == "") {return null}hexString = hexString.toUpperCase()val length = hexString.length / 2val hexChars = hexString.toCharArray()val d = ByteArray(length)for (i in 0..length - 1) {val pos = i * 2d[i] = (charToByte(hexChars[pos]).toInt() shl 4 or charToByte(hexChars[pos + 1]).toInt()).toByte()}return d}/*** Convert char to byte* @param c char* ** @return byte*/private fun charToByte(c: Char): Byte {return "0123456789ABCDEF".indexOf(c).toByte()}/* 这里我们可以将byte转换成int，然后利用Integer.toHexString(int)来转换成16进制字符串。* @param src byte[] data* @return hex string*/fun bytesToHexString(src: ByteArray?): String? {val stringBuilder = StringBuilder("")if (src == null || src.size <= 0) {return null}for (i in 0..src.size-1) {val v = src[i].toInt() and 0xFFval hv = Integer.toHexString(v)if (hv.length < 2) {stringBuilder.append(0)}stringBuilder.append(hv)}return stringBuilder.toString()}
}

因为是工具类，一般都应该是单例，在kotlin中 Object +类名 即表示该