Проверял многими вариантов, всё ок, но нсё равно валидатор не пропускает
package com.javarush.task.task19.task1918;
/*
Знакомство с тегами
*/
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
FileReader fileReader = new FileReader(reader.readLine());
reader.close();
StringBuilder fileImage = new StringBuilder();
int input;
while ((input = fileReader.read()) != -1) {
fileImage.append((char) input);
}
fileReader.close();
String pattern = "(<\\s*" + args[0] + "\\W)|(<\\s*\\/" + args[0] + ">)";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(fileImage);
int nesting = 0;
List<Integer> indices = new ArrayList<>();
while (m.find()) {
if (m.group().matches("<\\s*" + args[0] + " ") || m.group().matches("<\\s*" + args[0] + ">")) {
indices.add(m.start());
nesting++;
}
if (m.group().matches("<\\s*/" + args[0] + ">")) {
nesting--;
indices.add(m.end());
if (nesting == 0) {
for (int i = 0, j = indices.size() - 1; i < indices.size()/2; i++, j--) {
System.out.println(fileImage.substring(indices.get(i) , indices.get(j))
.replaceAll("\\n", "").replaceAll("\\t", "")
.replaceAll("<\\s*", "<").replaceAll("<\\s*\\/", "<\\/")
);
}
indices.clear();
}
}
}
}
}