}
        });
  }

  private CacheBuilderFactory cacheFactory() {
    return new CacheBuilderFactory()
        .withKeyStrengths(ImmutableSet.of(Strength.STRONG, Strength.WEAK))
        .withValueStrengths(ImmutableSet.copyOf(Strength.values()))
        .withConcurrencyLevels(ImmutableSet.of(1, 4, 16, 64))
        .withMaximumSizes(ImmutableSet.of(0, 1, 10, 100, 1000))

    checkStrength(map, Strength.WEAK, Strength.STRONG);
    assertSame(EntryFactory.WEAK, map.entryFactory);
  }

  public void testSetWeakValues() {
    LocalCache<Object, Object> map = makeLocalCache(createCacheBuilder().weakValues());
    checkStrength(map, Strength.STRONG, Strength.WEAK);
    assertSame(EntryFactory.STRONG, map.entryFactory);
  }

    checkStrength(map, Strength.WEAK, Strength.STRONG);
    assertSame(EntryFactory.WEAK, map.entryFactory);
  }

  public void testSetWeakValues() {
    LocalCache<Object, Object> map = makeLocalCache(createCacheBuilder().weakValues());
    checkStrength(map, Strength.STRONG, Strength.WEAK);
    assertSame(EntryFactory.STRONG, map.entryFactory);
  }

  boolean usesAccessEntries() {
    return usesAccessQueue() || recordsAccess();
  }

  boolean usesKeyReferences() {
    return keyStrength != Strength.STRONG;
  }

  boolean usesValueReferences() {
    return valueStrength != Strength.STRONG;
  }

  enum Strength {
    /*
     * TODO(kevinb): If we strongly reference the value and aren't loading, we needn't wrap the
     * value. This could save ~8 bytes per entry.

        return !((OptionalDouble) value).isPresent();
      } else if (value instanceof Optional) {
        return !((Optional) value).isPresent();
      } else if (value.getClass().isArray()) {
        return Array.getLength(value) == 0;
      }
      return false;
    }

    /**
     * Returns a string in the format specified by {@link MoreObjects#toStringHelper(Object)}.
     *

        }
      };

  private CacheBuilderFactory factoryWithAllKeyStrengths() {
    return new CacheBuilderFactory()
        .withKeyStrengths(ImmutableSet.of(STRONG, Strength.WEAK))
        .withValueStrengths(ImmutableSet.of(STRONG, Strength.WEAK, Strength.SOFT));
  }

  private Iterable<LoadingCache<Key, String>> caches() {
    CacheBuilderFactory factory = factoryWithAllKeyStrengths();
    return Iterables.transform(

    assertEquals(20, spec.maximumSize.intValue());
    assertNull(spec.maximumWeight);
    assertEquals(30, spec.concurrencyLevel.intValue());
    assertEquals(Strength.WEAK, spec.keyStrength);
    assertEquals(Strength.WEAK, spec.valueStrength);
    assertEquals(TimeUnit.HOURS, spec.writeExpirationTimeUnit);
    assertEquals(TimeUnit.MINUTES, spec.accessExpirationTimeUnit);

    VALUE
  }

  MapMaker setValueStrength(Strength strength) {
    checkState(valueStrength == null, "Value strength was already set to %s", valueStrength);
    valueStrength = checkNotNull(strength);
    if (strength != Strength.STRONG) {
      // STRONG could be used during deserialization.
      useCustomMap = true;
    }
    return this;
  }

  Strength getValueStrength() {

   * @throws IllegalStateException if the key strength was already set
   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);

import static org.junit.Assert.assertThrows;

import com.google.common.base.Function;
import com.google.common.collect.Interners.InternerImpl;
import com.google.common.collect.MapMakerInternalMap.Strength;
import com.google.common.testing.GcFinalization;
import com.google.common.testing.NullPointerTester;
import java.lang.ref.WeakReference;
import junit.framework.TestCase;

/**
 * Unit test for {@link Interners}.