looping through a 2D array 3 items at a time (Java) -

i having trouble trying figure out way move through 2d array 3 items @ time because has done in specific way.

the array has individuals rows , loci columns. have take 2 individuals @ time , compare them every third until end:

so if there 5 individuals total individual comparisons 0,1,2, 0,1,3, 0,1,4, 1,2,3, 1,2,4 , 2,3,4 

for each of these comparisons, have compare alleles @ each locus (each column represents allele, 2 columns 1 locus). looks

   locus1 locus2 locus3 ...      0  1   2  3   4  5   0 1  2   3  4   5  6   1 7  8   9  10  11 12  2 13 14  15 16  17 18   3 19 20  21 22  23 24  4 25 26  27 28  29 30   definite example of mean, have first set: 0,1,2.  first comparison of alleles: 1,2, 7,8 , 13, 14.  next comparison of alleles: 3,4, 9,10 , 15,16. last (assuming 3 loci) be: 5,6, 11,12, , 17,18. 

for every set of 6 alleles, have comparison. have finished code comparison testing. im not sure how loop through 2d array. thinking psuedo-code this:

 each pair of individuals (i,j)    each locus l       each individual k, not or j        if comparison test works           great        else           better luck next time 

i not want direct answer. guidance how tackle keeping array boundaries in mind. have not done search before.

i appreciate help! :)

there 2 ways can think of. these days, have classic external iterations, , more modern (but limited) internal stream iterations. i'll show both.

i'm assuming collection/array of type allele , called alleles, that's entirely arbitrary.

for external iteration, this:

for(allele : alleles) {     for(allele j : alleles) {         if(i == j) continue;         for(allele k : alleles) {             if(i == j || == k) continue;             docomparison(i, j, k);         }     } } 

basically, test equivalencies before entering next loop, , if find one, skip next entry.

for internal iteration (functional/streams), this

alleles.stream().foreach(i ->      alleles.stream().filter(j -> != j).foreach(j ->          alleles.stream().filter(k -> k != && k != j).foreach(k ->              docomparison(i, j, k)         )     ) ); 

in instance, may bit more efficient, filter(…) methods remove each potential conflict before beginning iteration. if you're dealing more three, though, may have clever iterations.

hopefully it. luck!