such as the following variable hexDigits

/ *

 * md5(+) 
 * 
 * @param str  
 * @return  MD5 
 */  
  
public static String MD5(String s) {  
    char hexDigits[]={"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"};         

    try {  
        byte[] btInput = s.getBytes();  
        // MD5 MessageDigest   
        MessageDigest mdInst = MessageDigest.getInstance("MD5");  
        //   
        mdInst.update(btInput);  
        //   
        byte[] md = mdInst.digest();  
        //   
        int j = md.length;  
        char str[] = new char[j * 2];  
        int k = 0;  
        for (int i = 0; i < j; iPP) {  
            byte byte0 = md[i];  
            str[kPP] = hexDigits[byte0 >>> 4 & 0xf];  
            str[kPP] = hexDigits[byte0 & 0xf];  
        }  
        return new String(str);  
    } catch (Exception e) {  
        e.printStackTrace();  
        return null;  
    }  
}