Programmer Think

An overview of Java collections (above) Preface First of all, why do I write such a blog (I always like to write why).Because by the end of the year recently, I was preparing for an interview, so I was making a technical summary of all aspects.Java collections are a very important part of Java, and they have spent a lot of time learning before ...

Based on JDK 1.7 Inheritance and implementation methods public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, java.io.Serializable { Let's look at the main methods add(E) to add elements /** * Appends the specified element to the end of this list. * * @param e e ...

3.1 synthesize tuples (1,2,3) and sets {"four",5,6} into a list 1 tuple,set,list = (1,2,3),{"four",5,6},[] 2 for i in tuple: 3 list.append(i) 4 for j in set: 5 list.append(j) 6 print(list) 3.2 set more than 5 elements to 0 and less than 5 elements to 1 in list [3,7,0,5,1,8] 1 list2 = [3,7,0,5,1,8] 2 print(list2) 3 for i ...

1, lodash version: 4.16.1 2, Function. 1,chunk 1) Meaning: unpack an array into multiple size arrays, and then make multiple arrays into a new array. 2) example. const _ = require('lodash'); console.log(_.chunk([1, 2, 3, 4, 5, 6], 4)); // Output: [[1, 2, 3, 4], [5, 6]] console.log(_.chunk([1, 2, 3, 4, 5, 6], 2)); // Outp ...

Composite partition is the partition of each partition in the partition table. The sub partition can use either HASH partition or KEY partition. This is also known as a subarea. Tip: mysql can only use HASH/KEY partition for sub partition, which is also different from ORACLE. The following issues need to be noted for composit ...

417. Pacific Atlantic Water Flow Title Description Given an m x n matrix of non-negative integers representing the height of each unit cell in a continent, the "Pacific ocean" touches the left and top edges of the matrix and the "Atlantic ocean" touches the right and bottom edges. Water can only flow in four directions (up ...

Now you have a total of N courses to choose, which are 0 to n-1. Some prerequisite courses are required before taking some courses. For example, to learn lesson 0, you need to complete lesson 1 first. We use a match to represent them: [0,1] Given the total number of courses and their prerequisites, return to the order ...

Log in, view and use Mysql-uroot-p password SHOW DATABASES; -- view all databases USE DB1; -- use one of the databases Departmental table CREATE TABLE DEPT( DEPTNO INT PRIMARY KEY, DNAME VARCHAR(14), -- Department name LOC VARCHAR(13)-- Department address ) ; INSERT INTO DEPT VALUES (10,'ACCOUNTING','NEW YOR ...

Overloaded C ා operator You can redefine or overload the operators built in C ා. Therefore, programmers can also use operators of user-defined types. Overloaded operators are functions with special names defined by the keyword operator followed by the symbol of the operator. Like other functions, overloaded operators have return types and par ...

Preface Concurrency is an unavoidable topic in Java development.Modern processors are multi-core, and multi-threaded programming is essential for better drying machine performance, so thread security is a required course for every Java Engineer. There are two general ways to address thread security issues: Synchronization: Use the Synchronized ...