java - Comparing an array to its mirror -

okay have method needs take in array full of ints, check against it's mirror see largest mirror matches to. example have array [7, 1, 2, 9, 7, 2, 1], largest array can match 2, being matched @ [1, 2].

right have broken 3 methods. 1 accepts array, reverses array , returns (mirrorarray). , 3rd being counting size of array matches(groupcount). here have far:

public int maxmirror(int[] nums) {   int[] revarray = mirrorarray(nums);    return groupcount(nums, revarray); }  private int[] mirrorarray(int[] nums) {   int[] newarray = new int[nums.length];    (int = nums.length-1, j = 0; >= 0; i--, j++) {     newarray[j] = nums[i];   }    return newarray; }  private int groupcount(int[] afor, int[] brev) {   int maxcount = 0;   int groupsize = 1;    //get afor value   (int = 0; < afor.length; i++) {     int[] tempa = arrays.copyofrange(afor, 0, groupsize);      //loop through brev , check matches     (int j = 0; j < brev.length; j++) {       int[] tempb = arrays.copyofrange(brev, j, j+groupsize);        if (arrays.equals(tempa, tempb)) {         maxcount = tempa.length;       }     }      groupsize++;   }   return maxcount; } 

it failing in 3rd method somewhere (returning 1 instead of 2) , i'm stumped why loops have arnt returning want. appreciated.

alright curious...

here's problem:

int[] tempa = arrays.copyofrange(afor, 0, groupsize); 

you comparing tempb first subarray of length groupsize of afor. change line to

int[] tempa = arrays.copyofrange(afor, i, + groupsize); 

and should work.

edit keep failure cases coming.. seems issue increment location of groupsize

   while (groupsize < afor.length) {       //get afor value       (int = 0; < afor.length; i++) {         int[] tempa = arrays.copyofrange(afor, i, + groupsize);          //loop through brev , check matches         (int j = 0; j < brev.length; j++) {           int[] tempb = arrays.copyofrange(brev, j, j+groupsize);            if (arrays.equals(tempa, tempb)) {             maxcount = groupsize;           }         }       }       groupsize++;   } 

this not efficient, , might fun exercise optimize. 1 starting approach start groupsize @ afor.length , decrement. maxcount assigned, can return.

edit 2

 int groupsize = afor.length;  while (groupsize >= 0) {       //get afor value       (int = 0; <= afor.length - groupsize; i++) { // note change         int[] tempa = arrays.copyofrange(afor, i, + groupsize);          //loop through brev , check matches         (int j = 0; j <= brev.length - groupsize; j++) { // note change           int[] tempb = arrays.copyofrange(brev, j, j+groupsize);            if (arrays.equals(tempa, tempb)) {             return groupsize;           }         }       }       groupsize--;   }   return 1; } 

what happening arrays.copyofrange filling out of bounds numbers zeroes. added exit opt mentioned earlier. there more optimizations can done