Есть мысли?
package com.javarush.task.task18.task1808;
/*
Разделение файла
*/
import java.io.*;
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();
String file3 = reader.readLine();
reader.close();
FileInputStream inputStream = new FileInputStream(file1);
FileOutputStream fileOutputStream1= new FileOutputStream(file2);
FileOutputStream fileOutputStream2 = new FileOutputStream(file3);
int half;
if (inputStream.available()/2 % 2 == 0) {
half = inputStream.available()/2;
} else {
half = (inputStream.available()-1)/2;
}
byte[] buffer1 = new byte[half];
byte[] buffer2 = new byte[inputStream.available() - half];
inputStream.read(buffer1);
fileOutputStream1.write(buffer1);
fileOutputStream1.close();
inputStream.read(buffer2);
fileOutputStream2.write(buffer2);
fileOutputStream2.close();
inputStream.close();
}
}