java - 用其他多个字符替换Java中的多个字符？

Question

我看到有一些与此类似的问题，但那里的答案并没有真正帮助我。不管怎样，我有一个像这样的字符串“今天是星期六”。我需要将每个字符“a”更改为“b”，将每个字符“o”更改为“f”。基本上，用多个字符替换多个字符。现在，我尝试做这样的事情:

String string.replace("a","b").replace("o","f");

但它只进行第一次替换。我尝试过使用 Stringbuilder:

stringBuilder.append(string);
for (int i=0; i<stringBuilder.length(); i++){
    char c=stringBuilder.charAt(i);
    if (c=='a'){
        I don't know how to replace it here to 'b'...
    }
}

stringBuilder.toString();

我读过我可以使用 map ，但我以前从未使用过它们，也不知道该怎么做。谁能帮我解决这个问题吗？

Answer 1

听起来您想要一个类似于 SQL TRANSLATE 函数的方法。

public static String translate(String input, String fromChars, String toChars) {
    if (fromChars.isEmpty() || fromChars.length() != toChars.length())
        throw new IllegalArgumentException();
    if (input == null || input.isEmpty())
        return input;
    char[] buf = input.toCharArray();
    for (int i = 0; i < buf.length; i++) {
        char ch = buf[i];
        for (int j = 0; j < fromChars.length(); j++) {
            if (fromChars.charAt(j) == ch) {
                buf[i] = toChars.charAt(j);
                break;
            }
        }
    }
    return new String(buf);
}

测试

System.out.println(translate("Today is Saturday", "ao", "bf"));

输出

Tfdby is Sbturdby

<小时/>

这是一个使用 Map 的版本，它支持来自补充平面的 Unicode 字符，例如表情符号:

public static String translate(String input, String fromChars, String toChars) {
    // Build codepoint mapping table
    if (fromChars.isEmpty() || fromChars.length() < toChars.length()) {
        throw new IllegalArgumentException("fromChars cannot be shorter than toChars (" +
                fromChars.length() + " < " + toChars.length() + ")");
    }
    Map<Integer, String> map = new HashMap<>();
    for (int fromIdx = 0, fromEnd, toIdx = 0; fromIdx < fromChars.length(); fromIdx = fromEnd) {
        fromEnd = fromChars.offsetByCodePoints(fromIdx, 1);
        String mapped = "";
        if (toIdx < toChars.length()) {
            int toEnd = toChars.offsetByCodePoints(toIdx, 1);
            mapped = toChars.substring(toIdx, toEnd);
            toIdx = toEnd;
        }
        if (map.put(fromChars.codePointAt(fromIdx), mapped) != null) {
            throw new IllegalArgumentException("Duplicate value in fromChars at index " + fromIdx + ": " +
                                               fromChars.substring(fromIdx, fromEnd));
        }
    }

    // Map codepoints
    if (input == null || input.isEmpty())
        return input;
    StringBuilder buf = new StringBuilder();
    for (int idx = 0, end; idx < input.length(); idx = end) {
        end = input.offsetByCodePoints(idx, 1);
        String mapped = map.get(input.codePointAt(idx));
        buf.append(mapped != null ? mapped : input.substring(idx, end));
    }
    return buf.toString();
}

测试

System.out.println(translate("Today is Saturday 😀", "ao😀r", "bf😕"));

输出

Tfdby is Sbtudby 😕

请注意如何删除 r，因为 toChars 比 fromChars 短。这就是 SQL TRANSLATE 函数的工作原理。