如何用哈希图中的char替换字符串？

debugcn 发表于 Dev

用户名

我有一个可以编码的莫尔斯电码程序。现在，我想对其进行解码，但是我不知道如何用哈希映射中的字母替换一串加密字符。

这是解码方法：

for(int i = 0; i < userInput.length(); i++){
        if(i != 0){
            morse.append(' ');
        }
        morse.append(codeLibrary.get(userInput.charAt(i))); //Currentely the same as encoding, this line needs to change
    }
    return morse.toString();

这是我的哈希图：

public static final java.util.Map<Character, String> codeLibrary;
 static{
    codeLibrary = new HashMap<>();
    codeLibrary.put('a',".-");      codeLibrary.put('b',"-...");
    codeLibrary.put('c',"-.-.");    codeLibrary.put('d',"-..");
    codeLibrary.put('e',".");       codeLibrary.put('f',"..-.");
    codeLibrary.put('g',"--.");     codeLibrary.put('h',"....");
    codeLibrary.put('i',"..");      codeLibrary.put('j',".---");
    codeLibrary.put('k',"-.-");     codeLibrary.put('l',".-..");
    codeLibrary.put('m',"--");      codeLibrary.put('n',"-.");  
    codeLibrary.put('o',"---");     codeLibrary.put('p',".--.");
    codeLibrary.put('q',"--.-");    codeLibrary.put('r',".-.");
    codeLibrary.put('s',"...");     codeLibrary.put('t',"-");
    codeLibrary.put('u',"..-");     codeLibrary.put('v',"...-");
    codeLibrary.put('w',".--");     codeLibrary.put('x',"-..-");
    codeLibrary.put('y',"-.--");    codeLibrary.put('z',"--..");
    codeLibrary.put('1',".----");   codeLibrary.put('2',"..---");
    codeLibrary.put('3',"...--");   codeLibrary.put('4',".----");
    codeLibrary.put('5',".....");   codeLibrary.put('6',"-....");
    codeLibrary.put('7',"--...");   codeLibrary.put('8',"---..");
    codeLibrary.put('9',"----.");   codeLibrary.put('0',"-----");
    codeLibrary.put(' ',"/");

充满鳗鱼的气垫船

您将需要一个单独的Map，一个Map是一个Map<String, Character>，再一个aHashMap<String, Character>可以正常工作，用el填充它

如果这是学校的任务，那么我认为这是解决方案。如果这是用于实际应用程序，那么，继续，按照Jake King的建议使用Guava BiMap库。

编辑
你问：

这似乎是很长的路要走。不能插入值来检索密钥吗？

那不是普通地图的工作方式。您使用键来获取值，而不是相反。但这并不难，也不是很“长”。您甚至可以在同一循环中填充两个地图。

例如，...

import java.util.HashMap;
import java.util.Map;

public class MorseFun {
   public static final String[] LETTER_CODES = { ".-", "-...", "-.-.", "-..",
         ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.",
         "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--",
         "-..-", "-.--", "--.." };
   public static final String[] NUMBER_CODES = { "-----", ".----", "..---",
         "...--", ".----", ".....", "-....", "--...", "---..", "----." };

   private static Map<Character, String> charToCodeMap = new HashMap<>();
   private static Map<String, Character> codeToCharMap = new HashMap<>();

   public static void main(String[] args) {
      for (int i = 0; i < LETTER_CODES.length; i++) {
         char c = (char) ('a' + i);
         String s = LETTER_CODES[i];
         charToCodeMap.put(c, s);
         codeToCharMap.put(s, c);
      }

      for (int i = 0; i < NUMBER_CODES.length; i++) {
         char c = (char) ('0' + i);
         String s = LETTER_CODES[i];
         charToCodeMap.put(c, s);
         codeToCharMap.put(s, c);
      }



   }
}