import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main(String[] args) {
final String regex = "(?<=[A-Z][A-Z])[a-z]|(?<=[a-z])[A-Z]+";
final String string = "parsingHTTPorSomeURLrequestToday\n"
+ "enhanceThisGold\n"
+ "thisIsCOOL\n"
+ "xP\n"
+ "anotherACRONYMiTest\n"
+ "loadedTHISupLIKEaMaDmAnS\n"
+ "NoReplacement\n"
+ "NONEok\n"
+ "None\n"
+ "none\n"
+ "n";
final String subst = "_\\L$0";
final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);
// The substituted value will be contained in the result variable
final String result = matcher.replaceAll(subst);
System.out.println("Substitution result: " + result);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html