import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main(String[] args) {
final String regex = "(?<!XXY)(?<=Y)\\w(?=Y)(?!YYXX)";
final String string = "(?<!XXY)(?<=Y)\\w(?=Y)(?!YYXX)\n"
+ " ^ ^ ^ ^ ^\n"
+ " | | | | not before YYXX\n"
+ " | | |before Y\n"
+ " | |letter \n"
+ " | followed by Y\n"
+ "not followed by XXY\n\n"
+ "X0XYXYYX\n\n"
+ "X(?=Y) match X if before Y\n"
+ "X(?!Y) match X if not before Y\n"
+ "(?<=Y)X match X if followed by Y\n"
+ "(?<!Y)X match X if not followed by Y";
final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);
while (matcher.find()) {
System.out.println("Full match: " + matcher.group(0));
for (int i = 1; i <= matcher.groupCount(); i++) {
System.out.println("Group " + i + ": " + matcher.group(i));
}
}
}
}
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