• Design pattern: the meta pattern


    Enjoy Flyweight Intro Heyuan is a reusable object, which can reduce the memory allocation by reusing the Heyuan. Heyuan mode is to reduce the memory consumption and reuse the design pattern of existing objects as much as possible. Generally speaking, the reusable object is put into an external data structure and transferred to Heyuan when […]

  • MySQL learning notes: Composite Index – index push down


    Series articles: MySQL learning notes: combination index – leftmost principle MySQL learning notes: Composite Index – index push down MySQL learning notes: index failure Index push down Official website address:Index Condition Pushdown Optimization Personal understanding: After the ICP is turned on, when querying the index, it will check whether the invalid index (the index that […]

  • Under cocos2d-x + Lua, how to know what class a Lua object corresponds to C + +?


    print(tolua.type(obj)) That’s it. Small skills, save a lot of time, you don’t have to guess blindly in the future, especially when using various widgets on the UI side.

  • JS advanced — Summary inheritance


    Summary inheritance   Object oriented features: encapsulation, inheritance, polymorphism Inheritance, the relationship between classes, object-oriented language inheritance is for polymorphic services   JS is not an object-oriented language, but it can simulate object-oriented and inheritance, in order to save memory   Inheritance: Prototype function: data sharing, the purpose is: in order to save memory space, […]

  • Two methods for mongodb to modify data


    In mongodb, both the DB. Collection. Ipdate() and DB. Collection. Save() methods can modify existing documents in the collection. The DB. Collection. Update () method provides additional control over the modification. For example, DB. Collectoin. Update() modifies existing data or a set of documents that match the query criteria. The DB. Collection. Save () method […]

  • Solution to update field to null by JPA save() method


    This article mainly introduces the solution of JPA save() method to update the field to null. The example code is introduced in detail in this article, which has a certain reference learning value for everyone’s study or work. You can refer to the following for your friends Today, there is a problem in the development. […]

  • Leetcode’s HOT100 series — 136. Numbers that only appear once


    Because I just wrote topic 461, which is very similar to that,461 uses exclusive or to calculate two different parts,Then this topic needs to exclude the same part and find the different part.Then we can make use of the features of exclusive or:1. The same is 0, so a ^ a = 0.2. The difference […]

  • HOT100 series of leetcode — 617. Merge binary tree


    Merging is the structure intersection part of two trees. The data is added. Otherwise, the non empty part is taken.Therefore, it is equivalent to traversing two trees at the same time:If neither tree node is empty, the data is added,Otherwise, the direct pointer copies the non empty nodes. Note: instead of applying for memory, the […]

  • Alibaba open source dragonwell JDK latest version 8.1.1-ga release


    Guidance:The new version has three major changes: it synchronizes the latest update of jdk8u222 GA in the upstream community of openjdk; it brings the official feature: g1elastichead; and it releases the experimental Windows version expected by users. It has been three months since the first official version of dragonwell JDK, 8.0.0-ga, was released. The stars […]

  • How to convert long links to short links?


    When sharing links, if the links are very long, it is easy to lead to incomplete copy of the links, so the links cannot be opened. Moreover, long links will give people a feeling of insecurity and reliability because they are too long, and the number of clicks will be greatly reduced. The short link […]