JAVA writing and loading an Object ArrayList

Question

I'm working on a program about students (saving the name, age and other information into objects and storing those objects into an arrayList). So far so good, I even got the JFrames to work exactly how I want them but the problem shows up when I try to write all that information in a text file.

How can I do that?

I tried the FileOutputStream with the ObjectOutputStream but I'm most likely not doing it right since I keep getting an IOException.

An example of a program storing an arrayList with 2 or more Objects containing 2 or more variables each is pretty much what I'm looking for.

As for the loading of that saved array, I think I can figure it out but an explaination on that would still be apreciated.

I've seen a couple of times on different websites people suggesting to do (but it gives me an IOException)

    FileOutputStream fos=new FileOutputStream("FileName.txt");
    ObjectOutputStream oos=new ObjectOutputStream(fos);

    oos.writeObject(myObjectArrayList);

Although it makes no technical difference, it would be better practice to use a different file extension, such as .dat or .ser. It simply helps define the contents of a file. — BlackBox, Aug 31 '13 at 14:29
@BlackBox s/format/extension/. The _format_ of the file doesn't really change. — C. K. Young, Aug 31 '13 at 14:30

score 3 · Answer 1 · answered Aug 31 '13 at 14:26

3

By default ArrayList is Serializable.

But the Objects inside the list also must implement Serializable interface.

While writing make sure that your Student class implemented the java.io.Serializable

answered Aug 31 '13 at 14:26

Suresh Atta

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score 0 · Accepted Answer · answered Aug 31 '13 at 14:26

0

While serializing your ArrayList to a file you need to make sure the object that list contains are also serializable. So make sure your Student class implements Serializable interface.

answered Aug 31 '13 at 14:26

Juned Ahsan

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It clearly states that I'm supposed to avoid this sort of thing but... Thanks a lot I've been stuck on this all day. – Java Learer Aug 31 '13 at 14:31

JAVA writing and loading an Object ArrayList

2 Answers2