让cap-1再赋值给n的目的是另找到的目标值大于或等于原值。例如二进制1000,十进制数值为8。如果不对它减1而直接操作,将得到答案10000,即16。显然不是结果。减1后二进制为111,再进行操作则会得到原来的数值1000,即8。 这种方法的效率非常高,可见Java8对容器优化了很多,很强哈。其他之后再进行分析吧。
Java中的HashMap是基于哈希表的Map接口的实现。它使用哈希表数据结构来存储键值对，其中键（key）的唯一性通过其hashCode()和equals()方法来确定。以下是HashMap的工作原理的详细解释：初始化：当你创建一个新的HashMap时，你可以指定它的初始容量和加载因子。初始容量是HashMap在创建时分配的数组大小，而加载因子是...
As we can see, there are no duplicates in the output.This works with custom objects when we overrideequalsandhashCode. 5. Using Lambdas and Streams Since Java 8, we can use the Stream API and lambda expressions to sort the map. All we need is to call thesortedmethod over the map’sstr...
Returns the number of key-value mappings in this map. Collection<V>values() Returns aCollectionview of the values contained in this map. Methods inherited from class java.util.AbstractMap equals,hashCode,toString Methods inherited from class java.lang.Object ...
There are many ways to compareHashMaps in Java. We can compare them using theequals()method. The default implementation compares each value. If we change the inner Map’s contents, the equality check fails. If the inner objects are all new instances every time in the case of user-defined...
HashMap Performance Improvements in Java 8 https://dzone.com/articles/hashmap-performance https://javarevisited.blogspot.com/2016/01/how-does-java-hashmap-or-linkedhahsmap-handles.html
难免会有若干谬误，欢迎指正。有问题在留言区谈论，如果觉得「还可以」，期望点赞转发。JDK1.7&JDK1.8 源码。Java Code Geeks，HashMap performance improvements in Java 8，2014。深入理解 hashcode() 和 HashMap 中的hash 算法JDK 源码中 HashMap 的 hash 方法原理是什么？Java 8系列之重新认识HashMap ...
3.6. Using Java 8 Streams with HashMap Java Stream API provides a concise way to process a collection of objects in a fluent manner. We can use the streams with HashMap class, primarily, for collecting an existing stream into HashMap. To collect Stream elements in the HashMap, we can us...
* @param m the map whose mappings are to be placed in this map * @throws NullPointerException if the specified map is null */ public HashMap(Map<? extends K, ? extends V> m) { this.loadFactor = DEFAULT_LOAD_FACTOR; putMapEntries(m, false); ...
A view of a ConcurrentHashMap as a Set of keys, in which additions may optionally be enabled by mapping to a common value. Nested classes/interfaces inherited from class java.util.AbstractMap AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V> Nested classes/interfaces inherited fr...