I'm attempting to read a file that contains serialized objects of type Contact into an ArrayList contactsCollection. The issue I'm having is that the objects Contact never get added into the ArrayList.
try
{
ObjectInputStream in = new ObjectInputStream(new FileInputStream("contactList.dat"));
Contact temp;
while (in.available()!=0)
{
temp = (Contact)in.readObject();
contactsCollection.add(temp);
}
in.close();
}
This is a known behaviour of ObjectInputStream.available, it always returns 0, see https://bugs.java.com/bugdatabase/view_bug?bug_id=4954570. Instead, you can read objects from file until EOFException is thrown, catch it and break.
Actually, you entire approach is wrong: You should serialize the List, not each object.
All List implementations are Serializable. Just create the list, add your onjbects and serialize the list - the objects in it will be serialized too (if they implement Serializable, which obviuosly your do).
Then to deserialize, simply read in the object, and voila - you have a list with all our objects added in already.
ArrayLists are Serializable provided their contents are. If the code that stores the Contacts to the stream has them in an ArrayList, just read the list in all at once.
If not, you probably want to have the code storing the Contacts store the length first:
try (FileInputStream fis = new FileInputStream("contactList.dat"),
ObjectInputStream in = new ObjectInputStream(fis)) {
int size = in.readInt();
for (final int i = 0; i < size; ++i) {
contacts.add((Contact) in.readObject());
}
} catch (IOException e) {
// Handle exception
}
Mixing available and readObject is unwise; available would tell how many bytes are available without causing the stream to block, except that Evegniy's comment applies. Those bytes may not represent a complete object.
If you can't get the code writing to the stream to put the size in first, you'll simply have to loop through and depend on the fact that an EOFException is an IOException.
in.available() != 0is not a valid test for end of stream.