InputStream.close（）做什么吗？

Question

As per the official documentation :

public void close() throws IOException

Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

So does it do nothing or something?

Answer 1

No it doesn't do anything, but InputStream is an abstract class where close isn't abstract (it implements java.io.Closeable ), it has an empty body. Implementers of InputStream can optionally override the method. FileInputStream closes the file input stream and releases any system resources where ByteInputStream does nothing.

Answer 2

The close() method of InputStream does nothing. The close() method of subclasses of InputStream may do something.

Answer 3

As @Kayaman says, InputStream is an abstract class and close method is not implemented there. If your are curious you can see this link which sows you close method on java.io.FileInputStream of openjdk version 8u40-b25, from GrepCode.