Java中的简单密码程序

Question

I'm trying to make a simple cipher in java that replaces value in an array and replaces it with a value in another array. One being a number, and the next being an alphabet.

I'm very new to Java, like last week new, and I'm still trying to understand the basics.The only way I have figured out to do this would be to declare each value and its equivalent, is there a shorter way to do this without adding 25 more unnecessary lines of code? I'm not too sure where to proceed from here. Any help would be greatly appreciated.

 class simpleCypher {

   String[] alpha;
    String[] numo;

    public static void main(String args[]) {
    String[] numo = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
            "12", "13", "14", "15", "16", "17", "18",
            "19", "20", "21", "22", "23", "24", "25", "26",};
    String[] alpha = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k",
            "l", "m", "n", "o", "p", "q", "r",
            "s", "t", "u", "v", "w", "x", "y", "z", };

    numo[21] = alpha[21];       
    System.out.println(numo[21]);


    }
}

Answer 1

If you want to associate each number with a specific character ; for example every time the program sees "1" it replaces it with "a" , I would say you should go for a HashMap. A HashMap is a data structure that stores two things a Key & a Value. each value is associated with a key and the HashMap maps unique keys to values.

The code would be as following:

class simpleCypher {

private static HashMap<String, String> hMap = new HashMap<>();

public static void main(String[] args){
    hMap.put("1", "a");
    hMap.put("2", "b");
    hMap.put("3", "c");
    // continue adding ...

    String[] numo = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
            "12", "13", "14", "15", "16", "17", "18",
            "19", "20", "21", "22", "23", "24", "25", "26",};


    for (int i = 0; i<numo.length ; i++){
        numo[i] = hMap.get(numo[i]);
        System.out.println(numo[i]);
    }
}
}

Answer 2

I advise you to use a Map and apply your cipher logic for each entry. Something like that:

  public static void main(String args []) {
    Map<Integer, Integer > map = new HashMap<>();

    for ( int i = 1; i <= 25; i ++ ){
      // do whatever you want in the logic
      int cypher = i * i + 1;
      map.put(i, cypher);
    }

    map.values().stream().forEach(cypher -> System.out.println(cypher));
  }