Programmer Group

1, What is a class loader class loader: responsible for loading. class files (stored physical files) into memory Class loading time:         1. Create an instance (object) of the class         2. Call the method of the class         3. Access class variables of classes or inter ...

Docker Basic composition of Docker Docker installation uname -r view system kernel Cat / etc / OS release to view the system configuration [root@palmer docker]# cat /etc/os-release NAME="CentOS Linux" VERSION="7 (Core)" ID="centos" ID_LIKE="rhel fedora" VERSION_ID="7" PRETTY_NAME="CentOS Linux 7 (Core)" ANSI_COLOR="0;31" CPE_NAME="cpe:/o ...

Use Socket in java to complete TCP protocol or UDP protocol communication Introduce TCP and UDP Two types of transmission protocols: TCP; UDP TCP is the abbreviation of Tranfer Control Protocol. It is a connection oriented protocol to ensure reliable transmission. Through TCP protocol transmission, we get a sequential error free data stream. ...

Four references to Java 1. Strong reference The most common reference type, which is not reclaimed even if there is not enough memory. Think: is obj1 a strong reference itself an object? Occupy memory? public class StrongReferenceDemo { public static void main(String[] args) { //obj1 is a strong reference to the actual object fr ...

524. Match the longest word in the dictionary by deleting letters One question per day on September 14, 2021 Title Description Give you a string s and a string array dictionary as a dictionary, find and return the longest string in the dictionary, which can be obtained by deleting some characters in S. If there is more than one answer, the ...

catalogue Find string length 1.strlen String function with unlimited length 2.strcpy 3.strcat 4.strcmp String function with limited length 5.strncpy,strncat,strncmp String lookup 6.strstr String cutting 7.strtok Error message report 8.strerror Memory operation function 9.memcpy 10.memmove 11.memcmp 12. memset other 13. Some ...

Spring Boot starter We know that Spring Boot greatly simplifies the initial construction and development process of the project, which are completed through the starter provided by Spring Boot. Pinda general permission system is developed based on Spring Boot, and some basic modules are starters in essence, so we need to have a comprehensive a ...

java foundation - Inner Class 1.1 non static internal class    defining an internal class is very simple. Just put one class inside another. The "class interior" here includes any position in the class. Internal classes can be defined even in methods (the internal classes defined in methods are called local internal classe ...

Let's start with a configuration file---- log4j.rootLogger=debug,stdout,logfile log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.Target=System.err log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout log4j.appender.logfile=org.apache.log4j.FileAppender log4j.appender.logfile.File=d:/msb.log log4j.appender.logf ...

Dynamic sql Dynamic SQL is one of the powerful features of MyBatis. Using dynamic SQL, we can flexibly splice SQL statements according to different conditions. Common dynamic SQL tags are as follows: ifchoose(when,otherwise)trim(where,set)foreach if When < if > sql < / if > is used, if the conditions are met, the SQL will ...