set() a Integer to zero; incr() by 1; get() returns 49 as the value about spymemcached HOT 1 CLOSED

You can't mix IntegerTranscoder and incr/decr.  incr/decr require the numbers 
to be
encoded as strings as they are language-agnostic server-side operations.

Here's a unit test that demonstrates what you're trying to do:

    public void testIncrDecrBug41() throws Exception {
        final String key="incrdecrbug41";

        // set to zero
        client.set(key, 86400, "0");

        // retrieve it to see if it worked
        assertEquals("0", client.get(key));

        // increment it
        assertEquals(1, client.incr(key, 1));

        // fetch it again to see if it worked
        assertEquals("1", client.get(key));
    }

Note that the reason you get 49 is because decimal 49 is the string "1".

incr and decr cause a lot of confusion for people because of the server-side
semantics.  In newer version of memcached (e.g. changes I don't have applied 
yet in
my binary branch), incr and decr will fail on non-numeric string values.  That 
is,
your first incr would throw an exception.