面试题

package com.code;

public class Code
{

public static void main(String[] args)
{
//String str = encode("__0a\\U\\3_4b\\\\");
// String str = encode("\\23b_2__f4");
String str = encode("b\\__\\1UL0123__");
System.out.println(str);
// System.out.println(decode(str));

   

}

public static String encode(String str)
{
if(str==null || str.length()==0)
return "";

StringBuffer strb = new StringBuffer();
char c;
for(int i=0; i<str.length(); i++)
{
c = str.charAt(i);
if(i > 0)
strb.append("_");

if(c == '_')
strb.append("\\UL");
else if(c<='0' || c >'9')
strb.append(c);
else if(i == str.length()-1)
strb.append(c);
else
{
    int b = Integer.parseInt(str.substring(i,i+1));
for(int a=0; a<=b; a++)
strb.append(str.charAt(i+1));
}
}
return strb.toString();
}

public static String decode(String str)
{
if(str==null || str.length()==0)
return "";

StringBuffer strb = new StringBuffer();
String[] strArr = str.split("_");
for(int i=0; i<strArr.length; i++)
{
if(strArr[i].equals("\\UL"))
strb.append("_");
else if(strArr[i].length() == 1)
strb.append(strArr[i]);
else
strb.append(strArr[i].length()-1);
}
return strb.toString();
}

}