  We present the first \emph{Solar Dynamics Observatory}/Atmospheric Imaging
Assembly observations of the large-amplitude longitudinal (LAL) oscillations in
the south and north parts (SP and NP) of a solar filament on 2012 April 7. Both
oscillations are triggered by flare activities close to the filament. The
period varies with filamentary threads, ranging from 44 to 67 min. The
oscillations of different threads are out of phase, and their velocity
amplitudes vary from 30 to 60 km s$^{-1}$, with a maximum displacement of about
25 Mm. The oscillations of the SP repeat for about 4 cycles without any
significant damping and then a nearby C2.4 flare causes the transition from the
LAL oscillations of the filament to its later eruption. The filament eruption
is also associated with a coronal mass ejection and a B6.8 flare. However, the
oscillations of the NP damp with time and die out at last. Our observations
show that the activated part of the SP repeatedly shows a helical motion. This
indicates that the magnetic structure of the filament is possibly modified
during this process. We suggest that the restoring force is the coupling of the
magnetic tension and gravity.
