a question about closing a stream/socket in java

Not checking the return value of close() is a common but nevertheless serious programming error. It is quite possible that errors on a previous write(2) operation are first reported at the final close(). Not checking the return value when closing the file may lead to silent loss of data. This can especially be observed with NFS and with disk quota.

While closing a readonly stream can't throw, java's IO framework can't check for that as it doesn't have statically checked read vs. write streams