Since Java 9 we can use a function as argument for the Matcher.replaceAll method. The function is invoked with a single argument of type MatchResult and must return a String value. The MatchResult object contains a found match we can get using the group method. If there are capturing groups in the regular expression used for replacing a value we can use group method with the capturing group index as argument.
In the following example we use the replaceAll method and we use a regular expression without and with capturing groups:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | package mrhaki.pattern;import java.util.function.Function;import java.util.regex.MatchResult;import java.util.regex.Pattern;public class Replace { public static void main(String[] args) { // Define a pattern to find text between brackets. Pattern admonition = Pattern.compile("\\[\\w+\\]"); // Sample text. String text = "[note] Pay attention. [info] Read more."; // Function to turn a found result for regular expression to upper case. Function<MatchResult, String> bigAdmonition = match -> match.group().toUpperCase(); assert admonition.matcher(text).replaceAll(bigAdmonition).equals("[NOTE] Pay attention. [INFO] Read more."); // Pattern for capturing numbers from string like: run20=390ms. Pattern boundaries = Pattern.compile("run(\\d+)=(\\d+)ms"); // Function to calculate seconds from milliseconds. Function<MatchResult, String> runResult = match -> { double time = Double.parseDouble(match.group(2)); return "Execution " + match.group(1) + " took " + (time / 1000) + " seconds."; }; assert boundaries.matcher("run20=390ms").replaceAll(runResult).equals("Execution 20 took 0.39 seconds."); }} |
Written with Java 14.
