Returning records from binary file

Question

Hi,
I am having trouble returning all the records from a binary file. As my knowledge is limited, I haven't been able to devise a method for counting the records and then displaying them one by one.
Any help you can provide is appreciated. Here is the basis of my code:
FileInputStream in = new FileInputStream("stud.bin");
ObjectInputStream s = new ObjectInputStream(in);
//System.out.println(s.available());
String studentFile = (String)s.readObject();
String gpaFile = (String)s.readObject();
classRoll.addStudent (studentFile, gpaFile);
System.out.println(studentFile + " has a GPA of " + gpaFile);
System.out.flush();
classRoll.addStudent("andy", "4.5");
s.close();
System.out.println(classRoll);

Answer 1

are these files in text format? You should use BufferedReader class- or some native, file component of the java.io API to retrieve the values. ObjectInputStreams are meant to exchange Object instances between resources, in other words you take a specific class, generalize it and then put it in a stream. You should not use ObjectStream for retrieving IO values because you are basically taking a specific class, making it general and then converting it back to a specific class. You should only use an ObjectInputStream when you need to send a current Object to some resource (often a remote resource) that does not have access to it.
Do some thing like:
FileInputStream f = new FileInputStream("file");
BufferedReader in = new BufferedReader(new InputStreamReader(f));
while(true) {
String line = in.readLine();
if (line == null)
break;
The above code is not necessarily the best, but it might help give you a sense of how to solve the problem. You should probably stick to the java.io API excusivly and avoid the ObjectStream class for this particular problem.