How to use regex in java to change prefix and suffix of matching substrings

Question

I'm wanting to (in Java) find any substrings in a string which start with say aba and end in say aca, where there is one or more non-whitespace chars between them.

For example" blingblangabablahacablingblang would find the substring abablahaca.

Then I want to replace each of those substrings, modifying the start to just b and the end to ca, but leaving the internal blah as it was.

For example" blingblangabablahacablingblang would be changed to blingblangbblahcablingblang.

Is there some way I can do this using String.replaceAll() ? There will be many instances within the original string to change.

Thanks for your help.

Answer 1

I don't know about the Java, but the regex should simply replace 'aba(.+?)aca' with 'b$1ca'.

Answer 2

You could try:

myString.replaceAll("aba(\\w*?)aca", "b$1ca") // would also match abaaca, without blah in the middle

or

myString.replaceAll("aba(\\w+?)aca", "b$1ca") // match onlu if there is a char between aba and aca

Answer 3

Try this pattern: aba[a-z]*aca

Pattern p = Pattern.compile("aba[a-z]*aca");
Matcher m = p.matcher("blingblangabablahacablingblang");
while (m.find())
   System.out.println(">" + m.group() + "<");

Answer 4

If it is guaranteed that both aba and aca are unique within the given character sequence, then you can use the good old String#replace instead of regular expressions:

String result = original.replace("aba","b").replace("aca", "ca");

Answer 5

Whats wrong with a simple if string.startsWith() and string.endsWith() and then replace the substring less then start and end and then rebuild the new string ?