И правда не пишет во второй файл, но не могу понять, почему. Помогите разообраться
package com.javarush.task.task19.task1908;
/*
Выделяем числа
*/
import java.io.*;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String fn1 = reader.readLine();
String fn2 = reader.readLine();
reader.close();
BufferedReader fileReader = new BufferedReader(new FileReader(fn1));
BufferedWriter fileWriter = new BufferedWriter(new FileWriter(fn2));
ArrayList<String> lines = new ArrayList<>();
String str = "";
while ((str = fileReader.readLine()) != null) {
lines.add(str);
}
for (String line : lines) {
if (isNumber(line)){
fileWriter.write(line + " ");
}
fileReader.close();
fileWriter.close();
}
}
private static boolean isNumber(String line) {
Pattern pattern = Pattern.compile("(^0$)|(^[1-9]([0-9])*)$");
Matcher matcher = pattern.matcher(line);
return matcher.find();
}
}