вроде все правильно выводит.
package com.javarush.task.task19.task1918;
/*
Знакомство с тегами
*/
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String fileName = reader.readLine();
reader.close();
BufferedReader bf = new BufferedReader(new FileReader(fileName));
String s = "";
while (bf.ready()) {
s += bf.readLine();
}
Document doc = Jsoup.parse(s);
Elements element = doc.getElementsByTag(args[0]);
for(Element el: element)
System.out.println(el);
bf.close();
}
}