Не проходит по закрытию потока

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String fileName = reader.readLine();
        FileOutputStream f1 = new FileOutputStream(new File(fileName));
        FileInputStream f2 = new FileInputStream(new File(reader.readLine()));
        FileInputStream f3 = new FileInputStream(new File(reader.readLine()));
        reader.close();

        while (f2.available()>0){
            int i = f2.read();
            f1.write(i);
        }
        f1.close();
        f2.close();
        f1=new FileOutputStream(new File(fileName),true);

        while (f3.available()>0){
            int i = f3.read();
            f1.write(i);
        }

        f1.close();
        f2.close();
        f3.close();

    }
}

f1=new FileOutputStream(new File(fileName),true);