Encoding and Decoding string

I have an issue while encoding and decoding string. If i encode string a to b then b to c means it works fine. If I convert finalstring means I got some extra characters. Please view my output for your clarifications am getting extra character at the end in output.

Here is my code.

public class DoubleByteReverse {

   public static void main(String args[]) {



      try{                    
             String a = new String("基本形");

             System.out.println("a value "+a);

             String b=new String(a.getBytes("Cp939"), "Cp500");

             System.out.println("b value "+b);

             String c=new String(b.getBytes("Cp500"), "Cp939");

             System.out.println("c value "+c);

             String g = new String("ã1áÃã°");

             String x = "0x0E";
            byte[] bytes = hexStringToByteArray(x);
            String st = new String(bytes,"Cp500");
            //System.out.println(st);

             String y = "0x0F";
            byte[] bytes1 = hexStringToByteArray(y);
            String en = new String(bytes1,"Cp500");
            //System.out.println(en);


             String finalstring =new String(st+g+en);

             System.out.println("whole string "+finalstring);

             String output=new String(finalstring.getBytes("Cp500"),"Cp939");

             System.out.println("output  "+output);

              }
             catch (UnsupportedEncodingException e){}
      }


   public static byte[] hexStringToByteArray(String hex) {
       int l = hex.length();
       byte[] data = new byte[l/2];
       for (int i = 0; i < l; i += 2) {
           data[i/2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
                                + Character.digit(hex.charAt(i+1), 16));
       }
       return data;
   }


}

Output:

a value 基本形 
b value ã1áÃã° 
c value 基本形 
whole string ã1áÃã° 
output  基本形�