Dfyjkt

I have an array

[2,5,7,9,1,3,4,6,8]

and I want a function

List<List<Integer>> split(List<Integer> list, int n)

which will separate the list intonarrays

for example:n=4,
result will be:

[2,1,8],
[5,3],
[7,4],
[9,6]

Note, the number was sampled averagely

Try this:

public static ArrayList<ArrayList<Integer>> split(ArrayList<Integer> list, int n)
 ArrayList<ArrayList<Integer>> resultArrays = new ArrayList<>();
 int pivot = 0;

 // Creates n ArrayLists.
 for(int i = 0 ; i < n ; i++)
 resultArrays.add(new ArrayList<>());
 

 // Add element from list to new ArrayLists.
 while(pivot != list.size())
 int p = pivot%n;
 resultArrays.get(p).add(list.get(pivot));
 pivot++;
 

 return resultArrays;

The result is the one you exactly you want.

[2,1,8],
[5,3],
[7,4],
[9,6]

pivot points list's element.(from 0 to the size-1)

p points the ArrayList of ArrayList's index.(As big as n, here 4)

So,

num / *(pivot) / ArrayList[p]

1: [2,5,7,9,1,3,4,6,8] -> ArrayList[0]
 *
2: [2,5,7,9,1,3,4,6,8] -> ArrayList[1]
 *
3: [2,5,7,9,1,3,4,6,8] -> ArrayList[2]
 *
4: [2,5,7,9,1,3,4,6,8] -> ArrayList[3]
 *
5: [2,5,7,9,1,3,4,6,8] -> ArrayList[0]
 *
6: [2,5,7,9,1,3,4,6,8] -> ArrayList[1]
 *
7: [2,5,7,9,1,3,4,6,8] -> ArrayList[2]
 *
8: [2,5,7,9,1,3,4,6,8] -> ArrayList[3]
 *
9: [2,5,7,9,1,3,4,6,8] -> ArrayList[0]
 *

Given a number of bins.

List<List<Integer>> result = new ArrayList<>();
while(result.size()<bins)
 result.add(new ArrayList<>());


int counter = 0;
for(Integer i: input)
 result.get(counter++%bins).add(i);

In Guava library there is a List.Partition method.

List<List<Integer>> split(List<Integer> list, int n) 
 return Lists.partition(list, n);

List<List<Integer>> split(List<Integer> list, int n)
 List<List<Integer>> result = new ArrayList<>();
 //add n ArrayLists to the result list
 IntStream.range(0, n).forEach(k->result.add(new ArrayList<>()));
 //iterate over the input list and add one element to one of the inner list of the result array
 Iterator i = list.iterator();
 while(i.hasNext())
 int count = 0;
 while(i.hasNext() && count < n)
 result.get(count).add((Integer) i.next());
 count++;
 
 
 return result;