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1.UDP definition       UDP is also called user data protocol [connectionless protocol]       Advantages: the safety and reliability of data cannot be guaranteed       Disadvantages: low consumption and high efficiency 2. Classes and methods required by UDP based n ...

1, File processing 1. Create an object of File class File Class creation function Method name: 1.public boolean creatNewFile()(When the file with this name does not exist, create a new empty file named by this abstract pathname) 2.public boolean mkdir()(Create a folder named after this abstract pathname) 3.public boolean mkdirs()(Create ...

In the Java language, all variables must be declared before they can be used. The basic format for declaring variables is as follows: type identifier [ = value][, identifier [= value] ...] ; Format description: Typee is a Java data type. identifier is the variable name. You can declare multiple variables of the same type separated by commas. ...

1. Basic concepts Basic concepts Class: The abstraction of objects of the same type, such as people, planets, cars, etc.Object: A specific instance of a class containing properties and methods such as a person, a planet, a vehicle, and so onAttributes: Used to describe certain characteristics of an object, such as a person's age, name, etc. ...

Registration of broadcasts is divided into static registration and dynamic registration. Static registration configures the receiver node in the xml and parses the xml file after the application starts. The specific registration process is handled by the PackagerManagerService. This article focuses on the dynamic registration of broadcasts, i.e ...

1. Matching pattern Summary Similar to switch...case in java, but much more powerful and flexible.The goal is to solve the matching and processing problems when a pattern (value is also one of the patterns) is met.Instructions A pattern match consists of a series of alternatives, each starting with the keyword case. Each alternative cont ...

Objects and References Variable types in Java, except for the basic types, are referred to as reference types. Basic types: byte, short, int, long, float, double, char, boolean; Reference type: Array, String, Custom class; Objects in Java operate on them by reference: Example: Custom class Teacher(Teachers) class Teacher{     ...

Introduction to Thread Pools Java threads correspond to the threads of the system, and creating threads is expensive in system resources. Too many threads consume more system resources, and context switching of threads incurs system resource overhead. Thread pools can unify thread management, balance the direct relationship between threads ...

7. Callable interface 1. Multiple ways to create threads Creation MethodRemarksIntegrate Thread ClassNo return valueImplement Runnable InterfaceNo return valueThrough the Callable interfaceCan have a return valueThrough thread pools 2. Differences between Callable and Runnable interfaces DifferenceCallableRunnableIs there a return valueyesno ...

1, Tool preparation       1.maven   Version maven-3.8.2       2.tomcat   Version tomcat-8.5.65       3. Database   Version 8.0.24       4. The database source is c3p0   Version 0.9.5.2 2, Database construction statement Note: the following sql statement ...