Question

How to write a file that exists with FileOutputStream ? When i run two times this program, the second time oos and fos are null

 public class ReadFile {
    static FileOutputStream fos = null;
    static ObjectOutputStream oos = null;
    public static void main(String[] args) throws IOException, ClassNotFoundException {

        File f = new File("file.tmp");
        if (f.exists()) {
            //How to retreive an old oos to can write on old file ?
            oos.writeObject("12345");
            oos.writeObject("Today");
        }
        else
        {
            fos = new FileOutputStream("file.tmp");
            oos = new ObjectOutputStream(fos);
        }
        oos.close();
    }
 }

Answer 1

ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(f,true));

if you want to append to the file