https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.cache;

import com.google.common.annotations.GwtCompatible;


Calculates the weights of cache entries.

Author:Charles Fry
Since:11.0
/**
 * Calculates the weights of cache entries.
 *
 * @author Charles Fry
 * @since 11.0
 */
@GwtCompatible
@FunctionalInterface
public interface Weigher<K, V> {

  
Returns the weight of a cache entry. There is no unit for entry weights; rather they are simply
relative to each other.

Returns:the weight of the entry; must be non-negative
/**
   * Returns the weight of a cache entry. There is no unit for entry weights; rather they are simply
   * relative to each other.
   *
   * @return the weight of the entry; must be non-negative
   */
  int weigh(K key, V value);
}