public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
  /**
   * Returns the next element in the iteration, without advancing the iteration.
   *
   * <p>Calls to {@code peek()} should not change the state of the iteration, except that it
   * <i>may</i> prevent removal of the most recent element via {@link #remove()}.
   *
   * @throws NoSuchElementException if the iteration has no more elements according to {@link
   *     #hasNext()}

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import java.util.Set;

/**
 * Very simple powerSet iteration benchmark.
 *
 * @author Kevin Bourrillion
 */
public class PowerSetBenchmark {
  @Param({"2", "4", "8", "16"})
  int elements;

  Set<Set<Integer>> powerSet;

  @BeforeExperiment
  void setUp() {

import com.google.caliper.Param;
import com.google.common.collect.BenchmarkHelpers.SetImpl;
import com.google.common.collect.CollectionBenchmarkSampleData.Element;
import java.util.Set;

/**
 * Test iteration speed at various size for {@link Set} instances.
 *
 * @author Christopher Swenson
 */
public class SetIterationBenchmark {
  @Param({

import com.google.caliper.Param;
import com.google.common.collect.BenchmarkHelpers.SetImpl;
import com.google.common.collect.CollectionBenchmarkSampleData.Element;
import java.util.Set;

/**
 * Test iteration speed at various size for {@link Set} instances.
 *
 * @author Christopher Swenson
 */
public class SetIterationBenchmark {
  @Param({

public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
  /**
   * Returns the next element in the iteration, without advancing the iteration.
   *
   * <p>Calls to {@code peek()} should not change the state of the iteration, except that it
   * <i>may</i> prevent removal of the most recent element via {@link #remove()}.
   *
   * @throws NoSuchElementException if the iteration has no more elements according to {@link
   *     #hasNext()}

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.common.base.Preconditions;
import java.util.Random;

/**
 * Tests the speed of iteration of different iteration methods for collections.
 *
 * @author David Richter
 */
public class MultisetIteratorBenchmark {
  @Param({"0", "1", "16", "256", "4096", "65536"})
  int size;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.common.base.Preconditions;
import java.util.Random;

/**
 * Tests the speed of iteration of different iteration methods for collections.
 *
 * @author David Richter
 */
public class MultisetIteratorBenchmark {
  @Param({"0", "1", "16", "256", "4096", "65536"})
  int size;

    this.e4 = e4;
  }

  @Override
  public Iterator<E> iterator() {
    return asList().iterator();
  }

  public List<E> asList() {
    return Arrays.asList(e0(), e1(), e2(), e3(), e4());
  }

  public static class Strings extends SampleElements<String> {
    public Strings() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super("b", "a", "c", "d", "e");
    }

Benchmarks can use the new [B.Loop] method in `for b.Loop() { ... }` loops to determine if iteration should continue....

    this.e4 = e4;
  }

  @Override
  public Iterator<E> iterator() {
    return asList().iterator();
  }

  public List<E> asList() {
    return Arrays.asList(e0(), e1(), e2(), e3(), e4());
  }

  public static class Strings extends SampleElements<String> {
    public Strings() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super("b", "a", "c", "d", "e");
    }