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。
在Java 8之前的实现中是用链表解决冲突的，在产生碰撞的情况下，进行get时，两步的时间复杂度是O(1)+O(n)。因此，当碰撞很厉害的时候n很大，O(n)的速度显然是影响速度的。因此在Java 8中，利用红黑树替换链表，这样复杂度就变成了O(1)+O(logn)了，这样在n很大的时候，能够比较理想的解决这个问题，在Java...
In our last post, we discussed the top five momentum builders for adoption of Java 8 in enterprises. In this post, we will dive deeper into JDK 8’s new strategy for dealing with HashMap collisions. Hash collision degrades the performance of HashMap significantly. With this new approach, ...
Now, Java doesn’t have any built-in deep copy implementations.So to make a deep copy, either we can override theclone()method or use a serialization-deserialization technique. Apache Commons hasSerializationUtilswith aclone()method to create a deep copy. For this, any class to be included i...
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use. But these can also be overused and fall into some common pitfalls. To get a better understandi...
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
Java HashMap Java 集合框架 HashMap 是一个散列表,它存储的内容是键值对(key-value)映射。 HashMap 实现了 Map 接口,根据键的 HashCode 值存储数据,具有很快的访问速度,最多允许一条记录的键为 null,不支持线程同步。 HashMap 是无序的,即不会记录插入的顺序。 H
Explanation of HashMap's Working Principles in Java:Initialization: When a new HashMap is created, you can specify its initial capacity and load factor. The initial capacity is the size of the array allocated to the HashMap upon creation, while the load factor is a floating-point number used...
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 ...
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...