can't verify 3rd and 4th condition, why?
package com.codegym.task.task18.task1819;
import java.io.*;
import java.util.*;
/*
Combining files
1.Make a buffer and read file into it.
2.Write the content of the secomd file to first
*/
public class Solution {
public static void main(String[] args) throws IOException{
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String fileName1= reader.readLine();
String fileName2= reader.readLine();
FileInputStream file1Input = new FileInputStream(fileName1);
FileInputStream file2 = new FileInputStream(fileName2);
FileOutputStream file1Out = new FileOutputStream(fileName1);
int[] buffer = new int[file1Input.available()];
for(int i = 0; i < file1Input.available(); i++){
int data = file1Input.read();
buffer[i] = data;
}
while(file2.available() > 0){
int data = file2.read();
file1Out.write(data);
}
for(int i = 0; i < buffer.length; i++){
file1Out.write(buffer[i]);
}
file1Input.close();
file2.close();
file1Out.close();
}
}