Question

Do you think this code close correctly the output stream entry ? Knowing that this is not the same type of output stream.

OutputStream out = new JarOutputStream(new FileInputstrem(fileName));
                       ...
((ZipOutputStream)out).closeEntry();

But considering that the both are output stream, I thought they were closing in the same way. And therefore in my case ((ZipOutputStream)out).closeEntry(); was the same as ((JarOutputStream)out).closeEntry();

Can you confirm that if you think is true or correct me if is wrong ?
Thanks.

Answer 1

If you need to call methods that are specific to ZipOutputStream on your out variable, then its type should not be OutputStream, but ZipOutputStream:

ZipOutputStream out = new JarOutputStream(new FileInputstrem(fileName));
                   ...
out.closeEntry();

This doesn’t cause any problem, because since JarOutputStream extends ZipOutputStream, a JarOutputStream is also a ZipOutputStream (and is also an OutputStream, and is also an Object).