Monoalphabetic Enc / Dec

Question

我遇到的问题是只有解密才能给我正确的结果。代码在加密方面运行良好，但在解密时会返回错误的结果。 我不知道是什么问题，只有解密它不起作用。有人可以帮助我吗？

     //main
     public static void main(String[] args) {
    int key[]=new int[26];
     int ikey[]=new int[26];

            String EncMsg =JOptionPane.showInputDialog(null, "enter plain text ");
            String plaintext = (EncMsg).replaceAll("\\s","").toLowerCase();
            for(int h=0;h<key.length;h++){
            String MsgKey=JOptionPane.showInputDialog(null,"enter random keys");

            key[h]= Integer.parseInt(MsgKey);

            }


            //total means collect all letters in one sentence
            String total="";

         for (int i = 0; i < plaintext.length(); i++) {
        char ch = plaintext.charAt(i);
        int letterNumber = convertLetter2Number(ch);
        int enc = key[letterNumber];
        total += convertNumber2Letter(enc);


    }

     // generating inverted key array

      for (int i=0; i<26; i++)
    {
   for (int j =0; j<26; j++)
   {
    if(j== key[i])
    { 
     ikey[j] = i ;
     break;
  }}
  }

      String total2="";
       for (int i = 0; i < total.length(); i++) {
        char result = total.charAt(i);
        int letterNumber = convertLetter2Number(result);
        int dec= ikey[letterNumber];
        total2 += convertNumber2Letter(dec);


    }
       JOptionPane.showMessageDialog(null,"Encryption message : "+total);
         JOptionPane.showMessageDialog(null,"Decryption message : "+total2);

    }

     //convert number to letters ( it has to be random )     

    public static char convertNumber2Letter(int key){

    char[] letters = new char[26];

    letters[0]='b';
    letters[1]='a';
    letters[2]='d';
    letters[3]='c';
    letters[4]='f';
    letters[5]='e';
    letters[6]='h';
    letters[7]='g';
    letters[8]='j';
    letters[9]='i';
    letters[10]='l';
    letters[11]='k';
    letters[12]='n';
    letters[13]='m';
    letters[14]='p';
    letters[15]='o';
    letters[16]='r';
    letters[17]='q';
    letters[18]='t';
    letters[19]='s';
    letters[20]='v';
    letters[21]='u';
    letters[22]='x';
    letters[23]='w';
    letters[24]='z';
    letters[25]='y';

    return letters[key];


   }


     // convert letter to number ( arranged )
    public static int convertLetter2Number(char ltr){

    if(ltr=='a'){
        return 0;
    }else if(ltr=='b'){
        return 1;
    }else if(ltr=='c'){
        return 2;
    }else if(ltr=='d'){
        return 3;
    }else if(ltr=='e'){
        return 4;
    }else if(ltr=='f'){
        return 5;
    }else if(ltr=='g'){
        return 6;
    }else if(ltr=='h'){
        return 7;
    }else if(ltr=='i'){
        return 8;
    }else if(ltr=='j'){
        return 9;
    }else if(ltr=='k'){
        return 10;
    }else if(ltr=='l'){
        return 11;
    }else if(ltr=='m'){
        return 12;
    }else if(ltr=='n'){
        return 13;
    }else if(ltr=='o'){
        return 14;
    }else if(ltr=='p'){
        return 15;
    }else if(ltr=='q'){
        return 16;
    }else if(ltr=='r'){
        return 17;
    }else if(ltr=='s'){
        return 18;
    }else if(ltr=='t'){
        return 19;
    }else if(ltr=='u'){
        return 20;
    }else if(ltr=='v'){
        return 21;
    }else if(ltr=='w'){
        return 22;
    }else if(ltr=='x'){
        return 23;
    }else if(ltr=='y'){
        return 24;
    }else if(ltr=='z'){
        return 25;
    }

    else {
        return -1;
    }


    }}
  //end