  In this letter, we decode the newly observed charmoniumlike states, $Y(4320)$
and $Y(4390)$, by introducing interference effect between $\psi(4160)$ and
$\psi(4415)$, which plays a role of resonance killer for $Y(4320)$ and
$Y(4390)$. It means that two newly reported charmoniumlike states are not
genuine resonances, according to which we can naturally explain why two
well-established charmonia $\psi(4160)$ and $\psi(4415)$ are missing in the
cross sections of $e^+e^- \to \pi^+ \pi^- J/\psi$ and $\pi^+ \pi^- h_c$
simultaneously. To well describe the detailed data of these cross sections
around $\sqrt{s}=4.2$ GeV, our study further illustrates that a charmoniumlike
structure $Y(4220)$ must be introduced. As a charmonium, $Y(4220)$ should
dominantly decay into its open-charm channel $e^+e^- \to D^0 \pi^+ D^{\ast-}$,
which provides an extra support to $\psi(4S)$ assignment to $Y(4220)$. In fact,
this interference effect introduced to explain $Y(4320)$ and $Y(4390)$ gives a
typical example of non-resonant explanations to the observed $XYZ$ states,
which should be paid more attention especially before identifying the observed
$XYZ$ states as genuine resonances.
