One fall afternoon, Java master Bawan heard that the monk
Landhwa had been struggling with a straightforward
data-extraction program. Intrigued, Bawan visited the monk,
who was slouching low in his chair.
“The program runs out of memory,” yawned Landhwa, who had no
patience for such investigations. “True, it processes many
large files, but it does so one at a time, and retains only
the smallest snippet from each.”
“Show me,” said Bawan.
The monk sighed, pointing to the screen. “To process a file,
I read its lines into a List of Strings. This I search to
find the section of interest: a few short lines at most. I
extract that via subList, and store it in this static Map.
The code could not be simpler.”
Bawan nodded. “Meet me at midnight on the river dock, down
in the village,” he said. “I know who can help us, and the
journey is not a long one.”
That night Landhwa descended with a lantern to the foggy
banks. Spying a twinkling light on the water, he followed
the boardwalk past dozens of small watercraft to find small
master Bawan seated in the last rowboat at the end of the
pier. The master gestured to the oars.
“Upstream,” said Bawan.
Landhwa pulled at the oars alone, while the master sat
silently in the stern with arms folded. Each stroke against
the current was a painful struggle, yet somehow the little
craft inched its way forward through the fog. Hours passed.
Just when Landhwa was on the verge of collapse, Bawan
ordered him to dock at an ramshackle pier far from the last
village they’d passed. The master looped a coil of rope
around one of the pilings to anchor them.
“We wait,” said Bawan.
Dawn came, scattering the night fog, but still no one
approached from the banks. When he happened to glance
downriver, Landhwa discovered that their rowboat had been
towing another boat by an underwater line many yards long.
The lifting fog revealed another boat beyond that, and then
another and another; and though the tenth passed out of
sight beyond a bend in the river, Landhwa was certain that
he had unwittingly towed every boat in the river dock behind
them that night.
