java - 分割字符串，记住分隔符并将其附加为空格

Question

大家好，

我有一个看起来像这样的字符串(摩尔斯电码):

....x.x.-..x.-..x---xx...x-x.-x-.-.x-.-x---x...-x.x.-.x..-.x.-..x---x.--

单“x”表示该字母在此结束，双“x”表示整个单词结束。我有一张带有摩尔斯电码的 map 。我用“x”分割字符串，然后将每个编码字母与字典中的值进行比较，并将匹配的键附加到我的 StringBuilder，它工作正常，但我想在单词之间保留空格而不是双 xx。

我的一段代码:

private static final Map<Character, String> morseCode;
    static {
        morseCode = new HashMap<Character, String>();
        morseCode.put('h', "....");
        morseCode.put('e', ".");
        morseCode.put('l', ".-..");
        morseCode.put('o', "---");
        morseCode.put('s', "...");
        morseCode.put('t', "-");
        morseCode.put('a', ".-");
        morseCode.put('c', "-.-.");
        morseCode.put('k', "-.-");
        morseCode.put('v', "...-");
        morseCode.put('r', ".-.");
        morseCode.put('f', "..-.");
        morseCode.put('w', ".--");
    }

String decodedMorseTable = "....x.x.-..x.-..x---xx...x-x.-x-.-.x-.-x---x...-x.x.-.x..-.x.-..x---x.--"
StringBuilder decodedText = new StringBuilder();
String[] splitLetters = decodedMorseTable.split("x");
    for(String letter: splitLetters) {
        for(Map.Entry<Character, String> entry: morseCode.entrySet()) {
            if(entry.getValue().equals(letter))
                decodedText.append(entry.getKey());

输出:

hellostackoverflow

Answer 1

首先尝试将输入拆分为单独的单词(按xx)。然后像之前一样拆分每个单词:

String decodedMorseTable = "....x.x.-..x.-..x---xx...x-x.-x-.-.x-.-x---x...-x.x.-.x..-.x.-..x---x.--";
StringBuilder decodedText = new StringBuilder();
String[] words = decodedMorseTable.split("xx");
for (String word : words) {
    String[] splitLetters = word.split("x");
    for (String letter : splitLetters) {
        for (Map.Entry<Character, String> entry : morseCode.entrySet()) {
            if (entry.getValue().equals(letter))
                decodedText.append(entry.getKey());
        }
    }
    decodedText.append(" ");
 }

更新

如果您修改 morseCode 以将莫尔斯字母作为键，将字符作为值，那么代码会看起来更简单(避免第三个循环):

private static final Map<String, Character> morseCode;
static {
    morseCode = new HashMap<>();
    morseCode.put("....", 'h');
    morseCode.put(".", 'e');
    morseCode.put("", ' ');
...   


String[] splitLetters = word.split("x");
for (String letter : splitLetters) {
    decodedText.append(morseCode.get(letter));
}

Java 1.8+解决方案:

Arrays.stream(decodedMorseTable.split("x"))
      .map(morseCode::get)
      .forEach(decodedText::append);