java - Historical Arrays -

i've been approached task requires "historical" array references.
not sure if has correct name or not.
here's quick concept in visual form.

[nc] == no change array value  (v1)        (v2)        (v3)        (v4)    (result) [10]    ->  [13]    ->  [12]    ->  [13]        = 13 [5]     ->  [nc]    ->  [54]    ->  [nc]        = 54 [6]     ->  [3]     ->  [61]    ->  [30]        = 30 [7]     ->  [3]     ->  [27]    ->  [3]         = 3 [23]    ->  [nc]    ->  [nc]    ->  [nc]        = 23 [41]    ->  [48]    ->  [4]     ->  [48]        = 48 [12]    ->  [nc]    ->  [2]     ->  [nc]        = 2 

i need able pull dataset array set, example (psudo code):

int[] results1 = arrayset.get(v2); system.out.println(results1[1]); // prints 5  int[] results2 = arrayset.get(v4); system.out.println(results2[1]); // prints 54 

i have store 20 array sets second, reaching past 5 seconds.
so, 100 array sets in memory.

each array set contain around 200 values; amount quite large memory consumption.

my question you:

is there java implementation this, allow array values link older versions in array; or have make cloning whole array, , changing values need change? (plus suffer nasty memory drawback)

the total number of arrays need fixed, can preallocate them. use counter designate current array , cycle through.

you cannot avoid using memory, can avoid re-allocating new arrays. there complex data structures allow save 'unchanged' memory, case, seems keeping in fixed number of existing arrays enough.

i keep actual values in arrays, during update can copy old values , overwrite have changed.

if need know if current_array[i] changed respect old_array[i], can make quick comparison.