java - string manipulation : insert words at certain indexes in string, simultaneously -

i have searched lot couldn't find allow me insert words @ indexes simultaneously. example : have string :

rock climbing fun, love rock climbing.

i have hashmap words indicate index in string : e.g. :

rock -> 0,29 climbing -> 5,34 fun -> 17 

now question : want put [start] tag @ start of these words , [end] tag @ end of them, in string. can't 1 one since in case once insert [start] @ index 0, other indexes modified , i'll have recalculate them. there way in can insert of tags @ once or something? can suggest other solution problem?

i can't use regular expressions(replaceall method), since i'll have sentence :

rocks hard.

and hashmap :

rock -> 0 

i looking faster solutions here.

edit : sentence :

rocks hard frocks beautiful. rocks -> 0 

here don't want replace frocks tags.

this not doing want, consider alternative solution tries achieve goal via different means.

i suppose 2 different things, firstly, suppose there exists list<string> words, contains words want replace.

then code be:

public string inserttags(final string input) {     (string word : words) {         input.replace(word, "[start]" + word + "[end]");     }     return input; } 

second case, closer example not using indices, suppose there exists map<string, list<integer>>, contains words , indices replaces them @ in list representation.

then code be:

public string inserttags(final string input) {     (map.entry<string, list<integer>> entry : words.entryset()) {         string word = entry.getkey();         input.replace(word, "[start]" + word + "[end]");     }     return input; } 

the latter definately more complex , not use indices, preferably should rewrite former.

hope helps without having worry indices.