AnkitKiet

private static final int LIST_SIZE = 20;
private int chunkSize;
private List<Integer> expectedChunk;
private int chunkIndex;
private int partitionedSize;

private static final List<Integer> list = IntStream.range(0, LIST_SIZE + random.nextInt(13)).boxed().collect(toList());

@Setup(Level.Iteration)
public void setup() {

AnkitKiet

@Benchmark
public void A3_smallListStreamPartitioned() {
  final List<List<Integer>> result = list.stream()
    .collect(partitioned(chunkSize));
  assertThat(result).hasSize(partitionedSize);
  assertThat(result.get(chunkIndex)).isEqualTo(expectedChunk);
}

@Benchmark
public void A4_smallListToPartition() {

AnkitKiet

public final class Partition<T> extends AbstractList<List<T>> {

    private final List<T> list;
    private final int chunkSize;

    public Partition(List<T> list, int chunkSize) {
        this.list = new ArrayList<>(list);
        this.chunkSize = chunkSize;
    }

AnkitKiet

 @Benchmark
public void C3_hugeListStreamPartitioned() {
  final List<List<Integer>> result = list.stream()
    .collect(partitioned(chunkSize));
  
  assertThat(result).hasSize(expectedSize);
  assertThat(result.get(chunkIndex)).isEqualTo(expectedChunk);
}

@Benchmark