implement hashmap in java interview

There are several options for applying HashMap in a Java multithreaded environment: using thread-safe java.util.Hashtable as an alternative Use the Java.util.Collections.synchronizedMap method to wrap an existing HashMap object as thread-safe. Using the Java.util.concurrent.ConcurrentHashMap class as an alternative, it has very good performance.And the above seve

that hashmap is not used to store a small amount of data. In addition, considering the complexity of hash calculation, if you only like the key-value interface like map, but do not store a large amount of data, you should consider other maps. Java actually provides many types of map. The result of misuse of hashmap is that it can only develop "enterprise-level"

overflow zone 2, how HashMap in Java is implemented We can understand it as " array of list ". HashMap is actually implemented as a linear array, so the container that can be understood to store the data is a linear array.So how does a linear array implement key-value pairs to access data? Here

ObjectiveTwo days ago in the company's internal blog to see a colleague to share the online services hanging off cpu100% article, let me think of hashmap in the improper use of the death cycle problem, here do a collation and summary, also by the way review under HashMap.Directly on the test code　　Depending on the machine configuration and performance, the number of threads and put quantities of the test results variespublic class Hashmapinfiniteloopt

1: Even a map interface is implemented, the underlying data structure is the same, both are transient decorated entry array, transient modified variables will not be serialized is not persisted, the process of serialization will not include this variable, The lifetime of this variable is simply not persisted to the memory disk during the user's call. This facilitates the preservation of some sensitive information2:hashmap is insecure, cannot be synchr

1, HashMap initialization of literary writingHashMap is a commonly used data structure, usually used to do data dictionary or Hash lookup container. Ordinary youth would typically initialize this:hashmapMap.put ("name", "Test");Map.put ("Age", "20");After reading this code, many people will feel that this is too verbose, literary youth generally come:hashmap{Map.put ("name", "Test");Map.put ("Age", "20");}};It looks elegant, one step, one go's bright.

Recently busy, want to study with you and discuss some of the Java source code and its implementation of the data structure, Not a high-level thing, an interested casual look 1. Why map, take HashMap as an example Many times we have this requirement, we need to store the data in a key-value pair, based on the key to get the value (value can be a simple value, or it can be a custom object) Of course, the obj

From the source code analysis java Collection [HashMap], the source code javahashmap As we know, Map stores key-value pairs. Its basic unit is to implement Node static class Node You can see its function by looking at the definition. It stores an object next to the next node. Therefore, we can probably think of its storage method stored by the linked list. In f

HashMap is one of the most frequently-used and important data structures. It provides dictionary operations, and the efficiency of Insert, Search, and Delete operations is high. This article will try to use Java to implement a simplest HashMap. Because of its simplicity, it is easy to see the true design idea of HashMa