Java I/O - 如何刷新输出流后写入字节数组/String

import java.io.DataOutputStream;
import java.io.FileOutputStream;

public class Main {

  public static void main(String[] args) throws Exception {
    FileOutputStream fos = new FileOutputStream("C:/WriteByte.txt");
    DataOutputStream dos = new DataOutputStream(fos);
    dos.writeBytes("this is a test");

    dos.flush();
    dos.close();
  }
}