Please help
package pl.codegym.task.task19.task1910;
/*
Interpunkcja
*/
import java.io.*;
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));
String file1 = reader.readLine();
String file2 = reader.readLine();
reader.close();
FileReader fileReader = new FileReader(file1);
FileWriter fileWriter = new FileWriter(file2);
BufferedReader bufferedReader = new BufferedReader(fileReader);
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
String a;
String regex = "[^a-zA-Z0-9]";
while ((a = bufferedReader.readLine()) != null) {
a.replaceAll(regex,"");
bufferedWriter.write(a);
}
bufferedWriter.close();
fileReader.close();
bufferedReader.close();
fileWriter.close();
}
}