I am trying to read the number of line in a binary file using readObject, but I get IOException EOF. Am I doing this the right way?
FileInputStream istream = new FileInputStream(fileName);
ObjectInputStream ois = new ObjectInputStream(istream);
/** calculate number of items **/
int line_count = 0;
while( (String)ois.readObject() != null){
line_count++;
}
readObject()
doesn't return null
at EOF. You could catch the EOFException
and interpret it as EOF, but this would fail to distinguish a normal EOF from a file that has been truncated.
A better approach would be to use some meta-data. That is, rather than asking the ObjectInput
how many objects are in the stream, you should store the count somewhere. For example, you could create a meta-data class that records the count and other meta-data and store an instance as the first object in each file. Or you could create a special EOF marker class and store an instance as the last object in each file.