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Simple use of search In the previous chapter, we introduced the basic use of the document. If you are interested, you can refer to it Introduction to the core concept of elasticSearch (III): addition, deletion, modification and query of documents In this chapter, we will make a simple use of search. 1, Let's delete all the indexes in ...

The most elegant way to write a value in a Map that increases or decreases automatically or re operates a value without calling get() and put() I believe you can always meet such needs in the process of development: query a key value in the Map, add one if there is one, and put the new key value as 1 if there is no one (or perform other operat ...

[Java] use of learning notes 4- method preface Main contents: ☑️ Understanding and use of methods. ☑️ The understanding and application of recursion. Tip: the following is the main content of this article. The following cases can be used for reference 1, Basic usage of method 1. What is the method A method is a snippet of code ...

Original author: Hollis Enumeration usage 1 background Before the introduction of enumeration types in the java language, the common mode of representing enumeration types was to declare a set of constants with int. Previously, we usually used the public final static method to define the following codes: 1 for spring, 2 for summer, 3 for aut ...

Comparison process In LevelDB, there are two main types of comparison: Minor compact: This is the process of immutable persistence to Level 0. The most important requirement here is high performance, because once it is blocked, memtable cannot be written, but is there any way to convert it to immutable.major compaction: it is responsible ...

preface As for thread safety, the put method can expose the problem of thread safety. When two different hashcode s get the same index through hash calculation, they should form a linked list. However, if multiple threads are placed in the same index, it may be overwritten, which is when judging whether the table[index] is empty. No more nons ...

object The Object class is the root class of the class hierarchy. Each class uses Object as its superclass. Each class directly or indirectly inherits from the Object class. Common methods in Object include: public int hashCode() //Returns the hash code value of the object. // Note: the hash value is a value calculated according to the hash ...

array Arrays is a tool class that operates on arrays. Common member methods public static String toString(int[] a) //Convert array to string public static void sort(int[] a) //Sort the array public static int binarySearch(int[] a,int key) //Binary search The toString() source code is as follows: public static String toString(int[] a) { ...

preface In the software industry, AOP is the abbreviation of Aspect Oriented Programming, which means: Aspect Oriented Programming, a technology that realizes the unified maintenance of program functions through precompiled mode and dynamic agent during operation. AOP is the continuation of OOP, a hot spot in software development, an impor ...

Learn Java - day04 - Process Control Statements from scratch (2) & Methods 1. Process control statements 1. Dead cycle Dead Loop: A loop that cannot be terminated by self-control in a program Classification: Dead loop of for statement for ( ; ; ) { Loop body statement; } Dead loop of while statement while (true) { Loop body ...