What am I doing wrong?
Using multiple scanners on the same stream is the underlying problem. Scanners can (and will) consume the stream – this may (will) lead to unexpected side-effects. Best not to do it.
If the input is closed, then the input (but Strings have no close
method) is closed for everyone – and that’s not much fun for anyone.
Edit: “Details” on why multiple scanners are bad: Do not create multiple buffered wrappers on an InputStream
…any buffered wrapper is unsafe; this condition is also exploitable if a Scanner is used instead…
See also Java code question … scanner related? which also talks about some approaches.