Replacing multiple substrings in Java when replacement text overlaps search text

Question

Say you have the following string:

cat dog fish dog fish cat

You want to replace all cats with dogs, all do

Answer 1

Here's a method to do it without regex.

I noticed that every time a part of the string a gets replaced with b, b will always be part of the final string. So, you can ignore b from the string from then on.

Not only that, after replacing a with b, there will be a "space" left there. No replacement can take place across where b is supposed to be.

These actions add up to look a lot like split. split up the values (making the "space" in between strings), do further replacements for each string in the array, then joins them back.

For example:

// Original
"cat dog fish dog fish cat"

// Replace cat with dog
{"", "dog fish dog fish", ""}.join("dog")

// Replace dog with fish
{
    "",
    {"", " fish ", " fish"}.join("fish")
    ""
}.join("dog")

// Replace fish with cat
{
    "",
    {
        "",
        {" ", " "}.join("cat"),
        {" ", ""}.join("cat")
    }.join("fish")
    ""
}.join("dog")

So far the most intuitive way (to me) is to do this is recursively:

public static String replaceWithJointMap(String s, Map map) {
    // Base case
    if (map.size() == 0) {
        return s;
    }

    // Get some value in the map to replace
    Map.Entry pair = map.entrySet().iterator().next();
    String replaceFrom = (String) pair.getKey();
    String replaceTo = (String) pair.getValue();

    // Split the current string with the replaceFrom string
    // Use split with -1 so that trailing empty strings are included
    String[] splitString = s.split(Pattern.quote(replaceFrom), -1);

    // Apply replacements for each of the strings in the splitString
    HashMap replacementsLeft = new HashMap<>(map);
    replacementsLeft.remove(replaceFrom);

    for (int i=0; i

I don't think this is very efficient though.