Why roll up to Closeable first?

Question

While reading some Java source, I came across this line:

((Closeable) some_obj).close();

some_obj is obviously an instance of a class that implements the Closeable interface. My question is: why do they first throw some_obj into Closeable before calling close (). I can not just do

some_obj.close();

Answer 1

Assuming the compile-time type some_objimplements Closeable, then yes, you could.

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Answer 2

some_obj close(), .

Answer 3

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