BA21转换成21BA的算法：
String str1 = "BA21"; // 十六进制字符串 String str2 = ""; // 反转后的字符串 for (int i = str1.length() - 2; i >= 0; i = i - 2) <span style="white-space:pre"> </span>{ str2 += str1.substring(i,i+2); } System.out.println(str2);
Java合并两个数组
import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class Main { public static void main(String args[]) { String a[] = { "A", "E", "I" }; String b[] = { "O", "U" }; List list = new ArrayList(Arrays.asList(a)); list.addAll(Arrays.asList(b)); Object[] c = list.toArray(); System.out.println(Arrays.toString(c)); } }
char[]和byte[]的互转
// char转byte private byte[] getBytes (char[] chars) { Charset cs = Charset.forName ("UTF-8"); CharBuffer cb = CharBuffer.allocate (chars.length); cb.put (chars); cb.flip (); ByteBuffer bb = cs.encode (cb); return bb.array(); } // byte转char private char[] getChars (byte[] bytes) { Charset cs = Charset.forName ("UTF-8"); ByteBuffer bb = ByteBuffer.allocate (bytes.length); bb.put (bytes); bb.flip (); CharBuffer cb = cs.decode (bb); return cb.array(); }
其他的一些，注释部分有详细的说明：
public static double[] getYData(String string) { string = string.trim().replace(" ", ""); double[] data = new double[string.length() / 4];// 这里最好判断下字符串数据的长度 for (int i = 0; i < data.length; i++) { data[i] = parseHex(string.substring(4 * i, 4 * i + 4)); } return data; } /** * 将接收到的字节数组转化成16进制的字符串 * * @param b * @return * @throws Exception */ public static String getHexString(byte[] b) throws Exception { String result = ""; for (int i = 0; i < b.length; i++) { result += Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1); } return result; } /** * 将字符串转化成byte[],注意byte[]数组包含的是十六进制，但是打印的是显示十进制 * * @param hexString * @return */ public static byte[] getByteArray(String hexString) { return new BigInteger(hexString, 16).toByteArray(); } /** * 将十六进制的字符转变成十进制整型数据 * * @param str * @return */ public static int parseHex(String str) { int result = 0; try { int temp = Integer.parseInt(str.trim(), 16); result = temp; } catch (NumberFormatException e) { long ltemp = Long.parseLong(str.trim(), 16); result = (int) ltemp; } return result; } /** * 将十进制转换为指定长度的十六进制字符串 * @param algorism 十进制数字 * @param maxLength 转化长度 * @return algorismToHexString((s-5)/5,2) */ public static String algorismToHexString(int algorism,int maxLength) { String result = ""; result = Integer.toHexString(algorism); if (result.length() % 2 == 1) { result = "0" + result; } return patchHexString(result, maxLength); } /** * * @param str * @param maxLength * @return */ public static String patchHexString(String str,int maxLength) { String temp=""; for (int i = 0; i < maxLength-str.length(); i++) { temp="0"+temp; } str=(temp+str).substring(0, maxLength); return str; } /** * 合并两个byte数组 * @param byte_1 * @param byte_2 * @return */ public static byte[] byteMerger(byte[] byte_1, byte[] byte_2){ byte[] byte_3 = new byte[byte_1.length+byte_2.length]; System.arraycopy(byte_1, 0, byte_3, 0, byte_1.length); System.arraycopy(byte_2, 0, byte_3, byte_1.length, byte_2.length); return byte_3; } /** * * @param time积分时间 * @param counts扫描次数 * @return */ public static byte[] getCommand(int time,int counts) { String result = algorismToHexString((time-5)/5, 2)+algorismToHexString((counts*2), 2);//一开始搞混了 byte[] data = getByteArray(result); byte[] dataHex = byteMerger(data, data); for (int i = 0; i < dataHex.length; i++) { byte b = (byte)dataHex[i]; dataHex[i] = (byte)Integer.parseInt(Integer.toString( ( b & 0xff ) + 0x100, 16).substring( 1 ), 16); } return dataHex;//byte[]中数据以16进制显示 }
Java byte数据类型转换：
public class DataTypeChangeHelper { /** * 将一个单字节的byte转换成32位的int * * @param b * byte * @return convert result */ public static int unsignedByteToInt(byte b) { return (int) b & 0xFF; } /** * 将一个单字节的Byte转换成十六进制的数 * * @param b * byte * @return convert result */ public static String byteToHex(byte b) { int i = b & 0xFF; return Integer.toHexString(i); } /** * 将一个4byte的数组转换成32位的无符号int类型 * * @param buf * bytes buffer * @param pos byte[]中开始转换的位置 * @return convert result */ public static long unsigned4BytesToInt(byte[] buf, int pos) { int firstByte = 0; int secondByte = 0; int thirdByte = 0; int fourthByte = 0; int index = pos;//可以直接int index = 0; firstByte = (0x000000FF & ((int) buf[index])); secondByte = (0x000000FF & ((int) buf[index + 1])); thirdByte = (0x000000FF & ((int) buf[index + 2])); fourthByte = (0x000000FF & ((int) buf[index + 3])); index = index + 4; return ((long) (firstByte << 24 | secondByte << 16 | thirdByte << 8 | fourthByte)) & 0xFFFFFFFFL; } /** * 将16位的short转换成byte数组 * * @param s * short * @return byte[] 长度为2 * */ public static byte[] shortToByteArray(short s) { byte[] targets = new byte[2]; for (int i = 0; i < 2; i++) { int offset = (targets.length - 1 - i) * 8; targets[i] = (byte) ((s >>> offset) & 0xff); } return targets; } /** * 将32位整数转换成长度为4的byte数组 * * @param s * int * @return byte[] * */ public static byte[] intToByteArray(int s) { byte[] targets = new byte[2]; for (int i = 0; i < 4; i++) { int offset = (targets.length - 1 - i) * 8; targets[i] = (byte) ((s >>> offset) & 0xff); } return targets; } /** * long to byte[] * * @param s * long * @return byte[] * */ public static byte[] longToByteArray(long s) { byte[] targets = new byte[2]; for (int i = 0; i < 8; i++) { int offset = (targets.length - 1 - i) * 8; targets[i] = (byte) ((s >>> offset) & 0xff); } return targets; } /** 32位int转byte[] */ public static byte[] int2byte(int res) { byte[] targets = new byte[4]; targets[0] = (byte) (res & 0xff);// 最低位 targets[1] = (byte) ((res >> 8) & 0xff);// 次低位 targets[2] = (byte) ((res >> 16) & 0xff);// 次高位 targets[3] = (byte) (res >>> 24);// 最高位,无符号右移。 return targets; } /** * 将长度为2的byte数组转换为16位int * * @param res * byte[] * @return int * */ public static int byte2int(byte[] res) { // res = InversionByte(res); // 一个byte数据左移24位变成0x??000000，再右移8位变成0x00??0000 int targets = (res[0] & 0xff) | ((res[1] << 8) & 0xff00); // | 表示安位或 return targets; } }
/** * 把字符串中间多余的空格去掉，只保留一个空格,比如字符串“hello my sister Helen”运算之后的结果为“hello my sister Helen” * @param string * @return */ public static String deleteMidTrim(String string) { String result = ""; Pattern pattern = Pattern.compile("\s+"); Matcher matcher = pattern.matcher(string.trim()); result = matcher.replaceAll(" "); return result; }