リストから、固定の長さで並びを保持したリストのリストを求める。

リストと連続させる数を指定して、List の List で結果を求める。

public static <T> List<List<T>> lengthSequencelist(List<T> list, int length){
   int last = list.size() - length + 1;
   return Stream.concat(
      IntStream.range(0, last).boxed().map(i->list.subList(i, i + length))
      , IntStream.range(last, list.size()).boxed().map(i->list.subList(i, list.size()))
   ).collect(Collectors.toList());
}

"A"～"Z" のリスト

List<String> list = Arrays.asList("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");

連続7個の組みで、リストを作成

lengthSequencelist(list, 7).stream().forEach(System.out::println);

結果

[A, B, C, D, E, F, G]
[B, C, D, E, F, G, H]
[C, D, E, F, G, H, I]
[D, E, F, G, H, I, J]
[E, F, G, H, I, J, K]
[F, G, H, I, J, K, L]
[G, H, I, J, K, L, M]
[H, I, J, K, L, M, N]
[I, J, K, L, M, N, O]
[J, K, L, M, N, O, P]
[K, L, M, N, O, P, Q]
[L, M, N, O, P, Q, R]
[M, N, O, P, Q, R, S]
[N, O, P, Q, R, S, T]
[O, P, Q, R, S, T, U]
[P, Q, R, S, T, U, V]
[Q, R, S, T, U, V, W]
[R, S, T, U, V, W, X]
[S, T, U, V, W, X, Y]
[T, U, V, W, X, Y, Z]
[U, V, W, X, Y, Z]
[V, W, X, Y, Z]
[W, X, Y, Z]
[X, Y, Z]
[Y, Z]
[Z]

Stream<List<T>> を求める場合、

public static <T> Stream<List<T>> lengthSequenceStream(List<T> list, int length){
   int last = list.size() - length + 1;
   return Stream.concat(
      IntStream.range(0, last).boxed().map(i->list.subList(i, i + length))
      , IntStream.range(last, list.size()).boxed().map(i->list.subList(i, list.size()))
   );
}

lengthSequenceStream(list, 7).forEach(System.out::println);