How to replace specific characters with corresponding characters in java? [duplicate]

Answer 1

Map<String, String> replacementMap = new HashMap<String, String>();
replacementMap.put("ck", "k");
replacementMap.put("dd", "wr");
replacementMap.put("f", "m");
// ...

String resultStr = "Abck fffffdk wr fmck"; // whatever string to process
StringBuilder builder = new StringBuilder(resultStr); // wrap it in builder

Iterator<String> iterator = replacementMap.keySet().iterator();
while (iterator.hasNext()) {
    String strToReplace = iterator.next();
    replaceAll(builder, strToReplace, replacementMap.get(strToReplace));
}
System.out.println("Result is: " + builder.toString());

public static void replaceAll(StringBuilder builder, String from, String to) {
    int index = builder.indexOf(from);
    while (index != -1) {
        builder.replace(index, index + from.length(), to);
        index += to.length(); // Move to the end of the replacement
        index = builder.indexOf(from, index);
    }
}

The replaceAll() method was borrowed from this Jon Skeet's answer

Alternative to replaceAll() int his example is to use apache commons library, there is StrBuilder class which provides replaceAll() method. see this answer

Answer 2

Use an appendReplacement loop.

Here is a general purpose way to do it:

private static String replace(String input, Map<String, String> mappings) {
    StringBuffer buf = new StringBuffer();
    Matcher m = Pattern.compile(toRegex(mappings.keySet())).matcher(input);
    while (m.find())
        m.appendReplacement(buf, Matcher.quoteReplacement(mappings.get(m.group())));
    return m.appendTail(buf).toString();
}
private static String toRegex(Collection<String> keys) {
    return keys.stream().map(Pattern::quote).collect(Collectors.joining("|"));
}

If you're not using Java 8+, the second method would be:

private static String toRegex(Collection<String> keys) {
    StringBuilder regex = new StringBuilder();
    for (String key : keys) {
        if (regex.length() != 0)
            regex.append("|");
        regex.append(Pattern.quote(key));
    }
    return regex.toString();
}

Test code

Map<String, String> mappings = new HashMap<>();
mappings.put("ck","k");
mappings.put("dd","wr");
mappings.put("f", "m");
System.out.println(replace("odd flock", mappings)); // prints: owr mlok

See IDEONE for running version.