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1. Assignment Two assignment methods Static initialization: define the contents of the array directly from the beginning Dynamic initialization: open up the space first, and then assign values later. You can not assign all values (at this time, the initial values are not assigned, such as 0 and null) // statement int[] ids; //1.1 s ...

Article catalog The road to becoming a God is long and lonely. Today, I share a little knowledge about how to export and use the toolkit I wrote through the tool Eclipse into classes preface Tip: Here you can add the general contents to be recorded in this article: For example, with the continuous development of artificial intelligenc ...

Multi thread learning 1. Multithreading_ concept Multithreading, in short, is multitasking. Inter method call: an ordinary method call is a closed path from where to where. Multithreading: opens up multiple paths. 2. Multithreading_ Inherit Thread There are three ways to create threads: (1) Inherit Thread(2) Implement Runnable interfac ...

//Use the thread pool to perform a task executor.execute(() -> { // Do something }); //Closing the thread pool will prevent the submission of new tasks, but it will not affect the submitted tasks executor.shutdown(); //Close the thread pool, prevent new task submission, and interrupt the currently running thread executor.showdownNow( ...

Connection pool When JDBC executes an SQL statement, most of the time is wasted on creating and closing connections, and the user experience is very poor Connection pooling can be used to manage connections, so connection pooling is a buffering technology used to manage connections. Working process of connection pool The role of connection ...

1. Spring source code download address:         https://github.com/spring-projects/spring-framework , version 5.2 x 2. Install Gradle: Spring relies on Gradle build tools to manage package dependencies (1) Gradle download address: https://services.gradle.org/distributions/ or https://gradle.org/releases/ (2) Configure environment variabl ...

1, File upload Dependent jar packages: comments-fileupload.jar comments-io.jar 1. Form attribute enctype = "multipart / form data" method = "post"; 2. Request code and response code settings; 3. 3 steps to parse request object Create factory class: FileItemFactory factory=DisFileItemFactory(); Create parser: servlet ...

Custom control layer framework core file The core file of the control layer framework is xml file, and almost all frameworks use xml file as configuration file. web. As the core file of Java Web, xml will parse the web when the server tomcat starts xml file, read the information of servlet and servlet mapping node, store it in a map set to ...

catalogue Function Preview Back end main content Login panel Management panel Data panel    Menu bar Panel switching Operation database Main form key technology verification   Operating system process Beautify form Front end part   Registration interface jsp realizes front-end and back-end interaction Fu ...

1, What is polymorphism The three characteristics of object-oriented are encapsulation, inheritance and polymorphism.Definition of polymorphism: parent class reference variables can point to subclass objects, allowing different objects to call the same method, that is, the same method can have different implementation forms according to differ ...