Method capacity

guava/src/com/google/common/collect/Maps.java:262–283

Returns a capacity that is sufficient to keep the map from being resized as long as it grows no larger than expectedSize and the load factor is ≥ its default (0.75).

(int expectedSize)

   * larger than expectedSize and the load factor is ≥ its default (0.75).
   */
  static int capacity(int expectedSize) {
    if (expectedSize < 3) {
      checkNonnegative(expectedSize, "expectedSize");
      return expectedSize + 1;
    }
    if (expectedSize < Ints.MAX_POWER_OF_TWO) {
      // This seems to be consistent across JDKs. The capacity argument to HashMap and LinkedHashMap
      // ends up being used to compute a "threshold" size, beyond which the internal table
      // will be resized. That threshold is ceilingPowerOfTwo(capacity*loadFactor), where
      // loadFactor is 0.75 by default. So with the calculation here we ensure that the
      // threshold is equal to ceilingPowerOfTwo(expectedSize). There is a separate code
      // path when the first operation on the new map is putAll(otherMap). There, prior to
      // https://github.com/openjdk/jdk/commit/3e393047e12147a81e2899784b943923fc34da8e, a bug
      // meant that sometimes a too-large threshold is calculated. However, this new threshold is
      // independent of the initial capacity, except that it won't be lower than the threshold
      // computed from that capacity. Because the internal table is only allocated on the first
      // write, we won't see copying because of the new threshold. So it is always OK to use the
      // calculation here.
      return (int) ceil(expectedSize / 0.75);
    }
    return Integer.MAX_VALUE; // any large value
  }

  /**
   * Creates a <i>mutable</i>, empty, insertion-ordered {@code LinkedHashMap} instance.