How to adjust index in a string after removing some characters?

问题

I am very new to regex and text manipulation so this might be trivial for many but it is turning out to be quite a nuisance for me.

I have a string like so:

*text* text text text *text*

where the text b/w the * denotes the text that has to be bold
So the desired output is

text text text text text

I am halfway there using the following code

 val string = "*text* text text text *text*"
        val pattern = Pattern.compile("\\*")
        val matcher = pattern.matcher(string)
        val spannableString = SpannableString(string)
        var counter = 0
        val indexes = IntArray(1)

        while (matcher.find()) {
                if(counter==0){
                    indexes[0]=matcher.start()
                    counter+=1
                }else if(counter==1){
                spannableString.setSpan(
                    StyleSpan(Typeface.BOLD),
                    indexes[0],matcher.start(),
                    Spannable.SPAN_INCLUSIVE_EXCLUSIVE)
               counter+=1

            }
            if(counter==2){
                counter=0
            }
        }
        textView.text = spannableString
    }

The output right now is
*text* text text text *text* (the *s are bold as well)
I want to remove the *'s
I intend to use

val spannableString = SpannableString(string.replace("*",""))

to remove the *'s but after that, I am not able to adjust the indexes that need to be passed on. How do I do it? or is there a better way? Any help is greatly appreciated

回答1:

I implemented what you wanted in JavaScript. It should be somewhat similar in the language you are using.

The regex explained:

find an *
capture one or more non-* characters in between the asterisks ([^*]+)
find a second *
capture all matched g flag
replace the matches with the captured group $1 (and the tags).

let string = '*text* text text text *text*';
string = string.replace(/\*([^*]+)\*/g, '<strong>$1</strong>');
document.getElementById('span').innerHTML = string;

<span id='span'></span>

PS: if you omit the strong tags in the string it will just remove the *.

回答2:

IMO you don't really need a regex to solve your problem (There's a famous saying "If you're trying to solve a problem with RegEx, now you have 2 problems", and I use RegExs frequently enough to both agree and disagree).

You can use the indexOf method in String in a loop (Java, Kotlin) to find the *s, while constructing your end result in a SpannableStringBuilder:

Keep a variable pointing to the start of the current span (or -1 if no open spans).
In every iteration, you use indexOf starting from the last index found.
Every time you find an opening * you append the text from the last position to the current one to your builder.
Every time you find a closing * you append the text from the opening * to the closer, and set it as a bold span.
If you don't find a * at an iteration you append everything from the last stop to the builder
If you reach the end of the string and have an open * that was never closed you know you have an error. You can either apply a bold span or not (or throw).

Hope this helps.

Also, please don't hijack other questions with links to yours.

来源：https://stackoverflow.com/questions/59947482/how-to-adjust-index-in-a-string-after-removing-some-characters

标签

android

regex

textview

spannablestring