Warum ein Cast zu (byte)

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String filename1 = br.readLine();
        String filename2 = br.readLine();
        br.close();

        FileReader freader = new FileReader(filename1);
        FileWriter writer = new FileWriter(filename2);



        int count = 1;
        while (freader.ready()){
            if (count %2==0){
                int data = freader.read();
                writer.write((byte) data);
                count++;
                continue;
            }
            freader.read();
            count++;
        }

        freader.close();
        writer.close();

    }
}