*   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }
 *   // calculate square root
 * }
 * }</pre>
 *
 * <p>to be replaced with the more compact
 *
 * <pre>{@code
 * public static double sqrt(double value) {
 *   checkArgument(value >= 0, "input is negative: %s", value);
 *   // calculate square root
 * }
 * }</pre>
 *

    return new Builder<>(Ordering.natural());
  }

  /**
   * Returns a builder that creates immutable sorted maps with an explicit comparator. If the
   * comparator has a more general type than the map's keys, such as creating a {@code
   * SortedMap<Integer, String>} with a {@code Comparator<Number>}, use the {@link Builder}
   * constructor instead.
   *

 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }
 *   // calculate square root
 * }
 * }</pre>
 *
 * <p>to be replaced with the more compact
 *
 * <pre>{@code
 * public static double sqrt(double value) {
 *   checkArgument(value >= 0, "input is negative: %s", value);
 *   // calculate square root
 * }
 * }</pre>
 *

import java.util.logging.Level;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * An abstract implementation of {@link ListenableFuture}, intended for advanced users only. More
 * common ways to create a {@code ListenableFuture} include instantiating a {@link SettableFuture},
 * submitting a task to a {@link ListeningExecutorService}, and deriving a {@code Future} from an

  // TODO(user,lukes): consider adding volatile to all these fields since in current known JVMs
  // that should resolve the issue. This comes at the cost of adding more write barriers to the
  // implementations.

  private Futures() {}

  /**
   * Creates a {@code ListenableFuture} which has its value set immediately upon construction. The

    return new Builder<>(Ordering.natural());
  }

  /**
   * Returns a builder that creates immutable sorted maps with an explicit comparator. If the
   * comparator has a more general type than the map's keys, such as creating a {@code
   * SortedMap<Integer, String>} with a {@code Comparator<Number>}, use the {@link Builder}
   * constructor instead.
   *

        Maps.uniqueIndex(
            INT_TO_STRING_MAP.values().iterator(), Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  /** Can't create the map if more than one value maps to the same key. */
  public void testUniqueIndexDuplicates() {
    try {
      Map<Integer, String> unused =
          Maps.uniqueIndex(ImmutableSet.of("one", "uno"), Functions.constant(1));

        Maps.uniqueIndex(
            INT_TO_STRING_MAP.values().iterator(), Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  /** Can't create the map if more than one value maps to the same key. */
  public void testUniqueIndexDuplicates() {
    try {
      Map<Integer, String> unused =
          Maps.uniqueIndex(ImmutableSet.of("one", "uno"), Functions.constant(1));

   * required by the selected eviction algorithm. As such, when writing unit tests it is not
   * uncommon to specify {@code concurrencyLevel(1)} in order to achieve more deterministic eviction
   * behavior.
   *
   * <p>Note that future implementations may abandon segment locking in favor of more advanced
   * concurrency controls.
   *
   * @return this {@code CacheBuilder} instance (for chaining)

   *
   * <p>This method has no effect (returns {@code this}) when called in GWT: it's unclear whether a
   * precomputed matcher is faster, but it certainly consumes more memory, which doesn't seem like a
   * worthwhile tradeoff in a browser.
   */
  public CharMatcher precomputed() {
    return Platform.precomputeCharMatcher(this);
  }