* or even removal, in a future release. An API bearing this annotation is exempt from any
 * compatibility guarantees made by its containing library. Note that the presence of this
 * annotation implies nothing about the quality or performance of the API in question, only the fact
 * that it is not "API-frozen."
 *
 * <p>It is generally safe for <i>applications</i> to depend on beta APIs, at the cost of some extra

   * probably not what you want to use.
   */
  @Override
  public final int hashCode() {
    // If we have at least 4 bytes (32 bits), just take the first 4 bytes. Since this is
    // already a (presumably) high-quality hash code, any four bytes of it will do.
    if (bits() >= 32) {
      return asInt();
    }
    // If we have less than 4 bytes, use them all.
    byte[] bytes = getBytesInternal();
    int val = (bytes[0] & 0xFF);

import com.google.common.annotations.VisibleForTesting;

/**
 * Implementation of FarmHash Fingerprint64, an open-source fingerprinting algorithm for strings.
 *
 * <p>Its speed is comparable to CityHash64, and its quality of hashing is at least as good.
 *
 * <p>Note to maintainers: This implementation relies on signed arithmetic being bit-wise equivalent
 * to unsigned arithmetic in all cases except:
 *
 * <ul>

 *
 * <h3>Desirable properties</h3>
 *
 * <p>A high-quality hash function strives for some subset of the following virtues:
 *
 * <ul>
 *   <li><b>collision-resistant:</b> while the definition above requires making at least <i>some</i>
 *       token attempt, one measure of the quality of a hash function is <i>how well</i> it succeeds

 * or even removal, in a future release. An API bearing this annotation is exempt from any
 * compatibility guarantees made by its containing library. Note that the presence of this
 * annotation implies nothing about the quality or performance of the API in question, only the fact
 * that it is not "API-frozen."
 *
 * <p>It is generally safe for <i>applications</i> to depend on beta APIs, at the cost of some extra

   *
   * <p>This is designed for generating persistent fingerprints of strings. It isn't
   * cryptographically secure, but it produces a high-quality hash with fewer collisions than some
   * alternatives we've used in the past.
   *
   * <p>FarmHash fingerprints are encoded by {@link HashCode#asBytes} in little-endian order. This

 * follows:
 *
 * <ul>
 *   <li>"{@code [group }<i>i</i>{@code , item }<i>j</i>{@code ]}" refers to the
 *       <i>j</i><sup>th</sup> item in the <i>i</i><sup>th</sup> equality group, where both equality
 *       groups and the items within equality groups are numbered starting from 1. When either a
 *       constructor argument or an equal object is provided, that becomes group 1.
 * </ul>
 *
 * @author Jim McMaster
 * @author Jige Yu

 * interface. It does not permit null keys or values.
 *
 * <p><b>Note:</b> by default, the returned map uses equality comparisons (the {@link Object#equals
 * equals} method) to determine equality for keys or values. However, if {@link #weakKeys} was
 * specified, the map uses identity ({@code ==}) comparisons instead for keys. Likewise, if {@link

  public void testTestEqualsEmptyLists() {
    equalsTester.addEqualityGroup(reference);
    equalsTester.testEquals();
  }

  /**
   * Test EqualsTester after populating equalObjects. This checks proper handling of equality and
   * verifies hashCode for valid objects
   */
  public void testTestEqualsEqualsObjects() {
    equalsTester.addEqualityGroup(reference, equalObject1, equalObject2);
    equalsTester.testEquals();
  }

 * reflected in that iterator. These iterators never throw {@link ConcurrentModificationException}.
 *
 * <p><b>Note:</b> by default, the returned cache uses equality comparisons (the {@link
 * Object#equals equals} method) to determine equality for keys or values. However, if {@link
 * #weakKeys} was specified, the cache uses identity ({@code ==}) comparisons instead for keys.