что не так с методом readAllBytes()? Ошибка компиляции.
package com.javarush.task.task18.task1818;
/*
Два в одном
*/
import java.io.*;
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String firstFileName = reader.readLine();
String secondFileName = reader.readLine();
String thirdFileName = reader.readLine();
FileOutputStream firstFile = new FileOutputStream(firstFileName);
FileInputStream secondFile = new FileInputStream(secondFileName);
FileInputStream thirdFile = new FileInputStream(thirdFileName);
byte[] buffer = secondFile.readAllBytes();
firstFile.write(buffer);
secondFile.close();
buffer = thirdFile.readAllBytes();
firstFile.write(buffer);
firstFile.close();
thirdFile.close();
}
}